bluuebunny/crossref_metadata_2025 huggingface dataset:
NEMATODES AND NEMATOMORPHS AS CONTROL AGENTS OF GRASSHOPPERS AND LOCUSTS
Authors: Baker Graeme L. , Capinera John L.
Published: April 2011

The relationship of nematodes and nematomorphs with grasshoppers and locusts is reviewed, emphasizing the actual or potential role of these parasitoids in microbial management. There are records of mermithids parasitizing grasshoppers worldwide, and they are considered important biological control agents in some grassland ecosystems of Europe, North and South America, Papua New Guinea, New Zealand, and Australia. Nematomorphs, although widely distributed, are uncommon parasitoids of grasshoppers, and their dependence on free-standing water for host infection and apparent host specificity are considered drawbacks to their use in biological control programmes. The ascaridids, spirarids, and acanthocephalans are parasites of birds and mammals, and may use grasshoppers as intermediate hosts. They have been shown to debilitate grasshopper hosts in laboratory studies, but their primary role as parasites of vertebrates precludes any consideration as biological control agents. Rhabditids do not naturally parasitize grasshoppers, but recent advances in mass-culturing techniques have given them a potential role as bioinsecticides for the control of grasshoppers. Quantitative data on the effects of nematodes and nematomorphs on agricultural pests, including grasshoppers and locusts, are generally lacking. However, there is evidence that some, particularly mermithids, are important in the population dynamics of grasshoppers and locusts. Keys to the identification of the various 'worms' found in grasshoppers and locusts are provided, including keys to the species of mermithids.
SEASONAL PATTERNS OF CADAVER PERSISTENCE AND SPORULATION BY THE FUNGAL PATHOGEN ENTOMOPHAGA GRYLLI (FRESENIUS) BATKO (ENTOMOPHTHORALES: ENTOMOPHTHORACEAE) INFECTING CAMNULA PELLUCIDA (SCUDDER) (ORTHOPTERA: ACRIDIDAE)
Authors: Sawyer A.J. , Ramos M.E. , Poprawski T.J. , Soper R.S. , Carruthers R.I.
Published: April 2011

Entomophaga grylli (Fresenius) Batko (North American pathotype 1) is a fungal pathogen of the clearwinged grasshopper, Camnula pellucida (Scudder). We present results from a field experiment conducted in Arizona in 1984, designed to investigate factors associated with seasonal patterns of cadaver persistence and sporulation by E. grylli. Rangeland plots at two sites were monitored daily for 8 weeks for the appearance of new cadavers of diseased grasshoppers during a natural epizootic. Cadavers were individually marked and revisited on subsequent days, when it was noted whether or not conidial sporulation was underway. Environmental variables were recorded by electronic data loggers. Daily probabilities of cadaver disappearance and fungal sporulation were analysed in relation to site, date, and various measures of cadaver status, sporulation history, and environmental variables by logistic regression analysis. The average daily rate of cadaver disappearance was 0.22, yielding an expected time to 50% disappearance of 2.8 days. The environmental factor most significantly associated with cadaver disappearance was rainfall, and the most important host factor was age of the cadaver. The probability that conidia would be discharged from a cadaver over the next 24 h was most dependent on whether or not conidial sporulation was underway already. This probably reflects a state of readiness for sporulation on the part of the fungus. Although the probability of sporulation declined with increasing age of a cadaver, high rates of sporulation were predicted under conditions of prolonged leaf wetness and high humidity at night, regardless of age of the cadaver. These results, together with the observation that in some cadavers sequences of sporulation were interspersed with periods of no sporulation, suggest that E. grylli may undergo cycles of dehydration and rehydration, in which conidial production is interrupted and then resumes in response to changing environmental conditions.
NOSEMATIDAE AND OTHER PROTOZOA AS AGENTS FOR CONTROL OF GRASSHOPPERS AND LOCUSTS: CURRENT STATUS AND PROSPECTS
Authors: Johnson Dan L.
Published: April 2011

Protozoa known to infect Acrididae include certain Amoebida (Phylum Rhizopoda), Eugregarinida, Neogregarinida (Phylum Apicomplexa) and at least one species from the Phylum Ciliophora, but are mainly Microsporida (Phylum Microspora). Among the Microsporida,Nosema locustaeCanning has been the most common subject of large-scale field testing as a potential microbial control of grasshoppers and locusts. Although there have been demonstrations of significant impacts of Protozoa such asNosemaspp. on survival, development, reproduction and feeding of grasshoppers and locusts, these candidates have not met the requirements for fast-acting control of Acrididae. However, recently discovered and as yet undiscovered Microspora and other Protozoa may offer reliable non-chemical control of grasshoppers and locusts. Research on candidates such asNosema locustaehas not been wasted effort; at a minimum, research invested toward development of methods of formulation, application, assessment and ecological fate of these potential microbial control agents has provided useful information needed to prepare for the eventuality of discovery of more fast-acting protozoa, and has contributed to development of field methods required for testing of other microbial agents. With improvements in understanding of insect behavioral and physiological responses, satisfactory short-term efficacy (perhaps resulting from combined formulations with behavioral modifiers or stressors) may allowN.locustae,N.cuneatumHenry,N.acridophagusHenry orJohenrea locustaeLange et al. to also serve a role in limiting acridid abundance and activity, either as an agent of biological control in sites requiring special care, or within a rangeland IPM context.
Revision of North American Species of Udea Guenée (Lepidoptera: Pyralidae)
Authors: Munroe Eugene
Published: April 2011

The North American species of Udea are revised on the basis of about 2500 specimens, with strongest representation in the difficult itysalis group. Twenty-three species and an additional 19 subspecies are recognized. Of these, the following six species and 18 additional subspecies are described as new: U. washingtonalis hollandi, interior B.C. and Mont.; U. w. nomensis, Alaska; U. w. pribilofensis, Pribilof Is.; U. indistinctalis johnstoni, Wash., ? Sask.; U. brevipalpis, Colo., Utah and ? Calif.; U. cacuminicola, Colo., Wyo.; U. beringialis, Yukon, Alaska; U. derasa, B.C.; U. livida, B.C., Wash., Utah; U. turmalis catronalis, N. Mex.; U. i. tularensis, Tulare Co., Calif.; U. t. griseor, Calif.; U. itysalis mertensialis, N.S.; U. i. rindgeorum, Tooele Co., Utah; U. i. kodiakensis, Alaska; U. i. albimontanensis, Ariz., N. Mex.; U. i. durango, Colo., Utah; U. i. wasatchensis, central Utah; U. i. clarkensis, southern Nev., Calif.; U. i. marinensis, San Francisco Bay region, Calif.; U. abstrusa subarctica, Northwest Territories, Yukon; U. abstrusa abstrusa, Alta., Sask., Man.; U. a. cordilleralis, Wyo., Colo., Utah, N. Mex.; U. a. pullmanensis, Wash. Five nominal species are transferred from other genera to Udea: Botis octosignalis Hulst, from Pyrausta; Ebulea straminea Warren, from Calamochrous; Botis vacunalis Grote, from Pyrausta; Phlyctaenia rusticalis Barnes and McDunnough and P. berberalis Barnes and McDunnough. U. straminea (Warren) is synonymized with U. octosignalis (Hulst) and U. galactalis (Dyar) with U. vacunalis (Grote). U. turmalis (Grote) is separated specifically from U. itysalis (Walker). Phiyctaenia angustalis Barnes and McDunnough is transferred from Udea to Evergestis.
Spring emergence of CanadianDelia radicumand synchronization with its natural enemy,Aleochara bilineata
Authors: Andreassen L.D. , Kuhlmann U. , Whistlecraft J.W. , Soroka J.J. , Mason P.G. , Akinremi O.O. , Holliday N.J.
Published: April 2011

To characterize time of spring emergence following post-diapause development,Delia radicum(L.) (Diptera: Anthomyiidae) from Saskatchewan, Manitoba, and southwestern Ontario were collected in fall, maintained over winter at 1 °C, then transferred to higher constant temperatures until adult emergence. At each location there were “early” and “late” phenotypes. Truncated normal models of temperature dependency of development rate were fitted for each phenotype from each location. We provide the first evidence of geographic variation in the criteria separating these phenotypes. Separation criteria and models for early and late phenotypes at the two prairie locations, approximately 700 km apart, were indistinguishable, but differed from those for Ontario. Prairie phenotypes developed more slowly than Ontario phenotypes, and more prairie individuals were of the late phenotype. Poor synchronization of spring emergence could impair predation ofD. radicumeggs by adultAleochara bilineataGyllenhal (Coleoptera: Staphylinidae).Aleochara bilineatafrom Manitoba were reared and development rates modelled as forD. radicum. Models of development rates for the two species, when combined with simulated soil temperatures for two prairie locations, suggest that emergence of adultA. bilineatais well synchronized with availability ofD. radicumeggs in prairie canola.
Influence of epicuticular-wax composition on the feeding pattern of a phytophagous insect: implications for host resistance
Authors: Daoust Simon P. , Mader Brian J. , Bauce Eric , Despland Emma , Dussutour Audrey , Albert P.J.
Published: April 2011

A white spruce, Picea glauca (Moench) Voss (Pinaceae), plantation in southern Quebec was found to contain two distinct types of trees, the first resistant and the second susceptible to attack by spruce budworm, Choristoneura fumiferana (Clemens) (Lepidoptera: Tortricidae). To identify the mechanisms of white spruce resistance to spruce budworm, we studied the role of epicuticular waxes, comparing (i) the foliar chemistry of susceptible and resistant trees and (ii) the feeding pattern of larvae at first contact with the foliage. Needles collected from resistant trees contained concentrations of the monoterpenes α-pinene and myrcene that were 307% and 476%, respectively, above those found in needles collected from susceptible trees. Although there were no significant differences in probing behaviour, significantly fewer larvae transitioned from probing to feeding on resistant needles; this led to fewer feeding bouts as well as a significantly shorter first meal. Removal of waxes increased the number of individuals transitioning from probing to feeding on resistant needles; this led to more feeding bouts. Our results demonstrate that monoterpenes influence the pattern of feeding of spruce budworm larvae as well as playing an important role in white spruce resistance.
Effect of supplemental phytase and ideal dietary amino acid ratios in covered and hulless-barley-based diets on pig performance and excretion of phosphorus and nitrogen in manure
Authors: Grandhi R. R.
Published: April 2011

A total of 144 (72 barrows + 72 gilts) crossbred pigs were used to determine the effect of feeding supplemental phytase and ideal dietary amino acid ratios in covered barley (CB) or hulless barley (HB)-based diets on growth performance, carcass quality, and excretion of phosphorus and nitrogen in manure during the grower and finisher periods. The three experimental grower and finisher diets were: 1) control diet (CB or HB) with Ca:P ratios according to National Research Counci l (NAS–NRC 1988), 2) the same as diet 1 but without added inorganic P, but supplemented with phytase (Novo Nordisk, Denmark) at 500 FTU kg–1, 3) the same as diet 2 with reduced dietary protein level, and supplemental amino acids lysine, threonine, and methionine to provide ideal dietary amino acid ratios of 0.70 for threonine to lysine and 0.30 for methionine to lysine. All diets were fed as pellets ad libitum in self-feeders with free access to drinking water. The ADG was not different (P > 0.10) between CB and HB or among the treatment diets during the grower, finisher and combined grower-finisher periods. The gain-to-feed ratios were higher (P < 0.01) for HB than for CB diets. They were also higher (P < 0.05) for diet 3 than for diet 1 during the finisher and combined grower-finisher periods. Carcass index and dressing percent were not different (P > 0.10) among the treatment diets. Supplemental phytase decreased (P < 0.05) the excretion of P during both grower and finisher periods. The combination of phytase and dietary ideal amino acid ratios decreased (P < 0.01) the excretion of both P and N. The ammonia and hydrogen sulphide production in stored liquid manure was not different among the diets 1, 2 and 3, and the urinary N excretion was closely related to ammonia production. These results indicate that replacing inorganic P with phytase and lowering the dietary protein level while supplementing amino acids in CB or HB diets can decrease the excretion of P up to 44.0% and N up to 28.0% in manure with no adverse effect on performanceof lean genotype pigs. Key words: Pigs, phytase, amino acids, phosphorus, nitrogen, excretion
Predicting loin-eye area from ultrasound and grading probe measurements of fat and muscle depths in pork carcasses
Authors: Pomar C. , Rivest J. , Jean dit Bailleul P. , Marcoux M.
Published: April 2011

The mathematical relationships between loin-eye area (m. longissimus thoracis) and linear measurements of fat and muscle depth were studied on digitalized images from 250 hog loins cut between the 3rd- and 4th-last ribs. Depth measurements were collected using (1) an Ultrascan 50 ultrasound system on immobilized, live animals, (2) a Hennessy grading probe on hanging carcasses under normal slaughtering conditions and (3) image analysis on digitalized images of chops separated between the 3rd- and 4th-last ribs. Loin-eye area was accurately predicted by its depth when the measurement was performed on digitalized images (R2 > 0.86; RSD < 1.87 cm2). The accuracy of the relationship between loin-eye area and muscle depth was reduced using ultrasound (R2 = 0.58, RSD = 3.29 cm2) or the probe (R2 = 0.29, RSD = 4.28 cm2) due to measurement errors on muscle depth. Muscle flatness, the perimeter irregularity or its angle in relation to the midline did not improve prediction accuracy. Consequently, muscle depth as measured by the Ultrascan 50 ultrasound system should be used with caution to predict loin-eye area since the measurement is only moderately accurate. Measurements obtained with the Hennessy probe under normal slaughtering conditions are not recommended for predicting loin-eye area in pork carcasses. Key words: Pork, backfat, muscle depth, loin-area, ultrasound, prediction
Effects of altering growth curve and age at photostimulation in female broiler breeders. 2. Egg production parameters
Authors: Renema R. A. , Robinson F. E. , Goerzen P. R. , Zuidhof M. J.
Published: April 2011

An experiment was conducted to evaluate the effect of differences in growth curve and age at photostimulation on egg production parameters and carcass traits at 61 wk of age in broiler breeder hens. Pullets were grown on one of three growth curves: STD (standard), LOW (150g lighter than STD) and HIGH (150 g heavier than STD ), and photostimulated at either 19 wk of age (19WK) or 21 wk of age (21WK). The egg production and BW of 36 birds per interaction were individually monitored from photostimulation to 61 wk of age. Individual, daily egg production records were analyzed for total, settable, and defective egg production, rate of production, sequence length, and egg weight. Eggs were incubated for determination of fertility, hatchability, and embryonic mortality parameters. All birds remaining at 61 wk of age were processed for determination of carcass and reproductive morphology. Unless otherwise stated, all significance was assessed at the P < 0.05 level.
Effect of true ileal digestible dietary methionine to lysine ratios on growth performance and carcass merit of boars, gilts and barrows selected for low backfat
Authors: Grandhi R. R. , Nyachoti C. M.
Published: April 2011

A total of 288 Landrace × Yorkshire boars, gilts and barrows selected for low backfat were used in two trials to determine the effect of an increased dietary ratio of true ileal digestible methionine to lysine on growth performance, carcass merit and nutrient utilization. The three experimental grower and finisher diets were: (1) barley-soybean meal diets with no supplemental amino acids as control containing true ileal digestible lysine at 0.45 and 0.36 g MJ–1 DE in grower and finisher diets, respectively, (2) the same as diet 1 with supplemental lysine to provide true ileal digestible lysine at 0.65 and 0.49 g MJ–1 DE, and supplemental threonine and methionine to give ratios of 0.7 and 0.3, respectively, to lysine on a true ileal digestible amino acid basis, and (3) the same as diet 2 with an increased true ileal digestible methionine to lysine ratio of 0.4. All diets were fed as pellets ad libitum in self-feeders, and with free access to drinking water. The ADG and FCE during the grower, finisher and overall periods were higher (P < 0.05) for diets 2 and 3 than for diet 1, but they were not different between diets 2 and 3 in boars, gilts and barrows. The lean growth rate and whole body protein accretion were also higher (P < 0.05) for diets 2 and 3 than for diet 1, but they were not different between diets 2 and 3 in boars, gilts and barrows. The apparent faecal digestibilities of dry matter and energy, as well as nitrogen retention and excretion, were similar (P > 0.05) for all the diets. The results indicated that boars and gilts in the present study may not have reached the maximum genetic potential for lean growth rate due to an inadequate feed and amino acid intake. A lack of improvement in pig performance with a higher dietary ratio of true ileal digestible methionine to lysine (0.40 vs. 0.3) indicated that the current NRC recommendations may be adequate. Key words: Pigs, amino acids, lysine, methionine, growth performance, nutrient metabolism.
Influence of condensed tannins on gut morphology in sheep fed Lotus pedunculatus
Authors: Walton J. P. , Waghorn G. C. , Plaizier J. C. , Birtles M. , McBride B. W.
Published: April 2011

Feeding forages containing condensed tannins (CT) can reduce intestinal absorption of amino acids (AA) and peptides. This experiment tested the hypothesis that CT in Lotus pedunculatus altered small intestinal mucosal morphology reducing absorptive capacity of the gut. Thirteen young Romney wethers were fed ad libitum either Lotus pedunculatus (cv. Grasslands Maku, N = 7) containing 5.5% CT in the dry matter (DM) or white clover-perennial ryegrass pasture (N = 6), which did not contain CT, for 4 wk. The wethers were euthanized at the end of the feeding trial and samples were collected for histological examination from the proximal and distal duodenum, proximal, mid-, and distal jejunum and ileum, and ventral rumen. There was no effect of feeding L. pedunculatus containing 5.5% CT (P > 0.05) on rumen or gut morphological parameters in sheep. The cause of reduced AA absorption in the presence of CT is not known, but this study suggests it is not due to changes in intestinal morphology. Key words: Lotus pedunculatus, condensed tannins, gut morphology, sheep
Evaluation of n-alkanes as markers for estimation of dry matter intake and digestibility in steers consuming all-forage or forage-concentrate diets
Authors: Moshtaghi Nia S. A. , Wittenberg M.
Published: April 2011

The study examined the reliability of the alkane-based and chromium (Cr)/in-vitro-based procedures relative to the total fecal collection (TC) technique for estimation of dry matter (DM) intake an d DM digestibility of forage or forage-concentrate diets fed to steers. Eight Holstein steers (208 ± 19.2 kg) were assigned to four dietary treatments in a three-period balanced incomplete block design. The four dietary treatments were: (1) 100% meadow brome grass hay (B); (2) 50% B + 50% alfalfa hay (BA); (3) 50% B + 50% barley grain (BB); and (4) 25% B + 25% alfalfa hay + 50% barley grain (BAB). Two types of hay were chosen to achieve a wide range of alkane intake. Appropriate portions of forages and grain were mixed as a total mixed ration and fed in two equal portions twice daily at 2.5% of body weight, DM basis. Two controlled-release capsules, one containing n-alkanes (C32 and C36) and the other chromic oxide, were placed into the steer's reticulo-rumen by oral administration on day 1 of each 30-d period. Total fecal output was collected twice daily from day 8 to 14 of each period to establish the fecal recovery of Cr and the alkanes, and to determine apparent DM digestibility. A rectal fecal grab sample was also taken every 4 h from day 15 to 16. Fecal recovery of the natural alkanes, C31 and C33, was low, ranging from 59.5 to 77.3%, whereas the range in fecal recovery of the dosed alkanes, C32 and C36, was 83.3 to 95.5%, and of Cr was 82.7 to 95.8% across the diets. The estimated DM intake was similar across all diets using the C31/C32 and C33/C32 alkane ratios; however, estimated DM intakes using the alkane method were significantly (P < 0.05) lower compared to TC and Cr/in vitro methods for the BB diet. Addition of barley to the forage diets resulted in a higher DM digestibility for BB and BAB diets by all methods. The estimated DM digestibility using the C31/C32 ratio was lower compared to the TC method for diet B, BA and BB, whereas the estimated DM digestibility using C33/C32 was lower only for the BB diet. Sampling every 4 h resulted in a significantly higher ratio of C 31 to C32 in feces compared to samples collected by the TC method. Rectal grab sampling did not change (P > 0.05) the estimated DM intake using either combination of alkane ratio. Key words: Alkanes, chromium oxide, dry matter intake, dry matter digestibility, steer
Characterization of a recombinant porcine follistatin in a heat shock expression system
Authors: Christensen C. R. , Kowalski J. , Chedrese P. J. , Misra V. , Laarveld B. , Redmond M. J.
Published: April 2011

The role of follistatin in ovarian function has yet to be fully elucidated; it is present in low concentration in vivo and it is difficult to obtain suitable quantities of follistatin for characterization. We have cloned porcine follistatin cDNA in an expression system that uses the heat shock protein promoter BoHSP70. Recombinant follistatin with apparent molecular masses of 39, 46, 48, 50 kDa was expressed and secreted into culture medium at concentrations of 400–500 μg × 20 mL-1 × 150 cm-2 flask (4 × 107 cells). In ligand blots, the recombinant follistatin was shown to be immunologically similar to native follistatin and to bind to recombinant activin A. Porcine granulosa cells dissected from 1–3 mm follicles from immature gilts were cultured with recombinant follistatin or with a follistatin monoclonal antibody to examine the activity of the recombinant follistatin. At a physiologically relevant concentration of 1 μg mL-1 the recombinant porcine follistatin suppressed the accumulation of estradiol-17β (P < 0.05). There was a trend for estradiol-17β accumulation in the presence of 10 μg mL-1 of monoclonal anti-follistatin antibody (P = 0.1). This expression system consistently produced large quantities of recombinant porcine follistatin, which is immunologically and biologically similar to follistatin, and is capable of independently inhibiting estratiol-17βproduction in vitro. Key words: Porcine, follistatin, heat shock promoter, glycoprotein, ovary, estradiol
Yield, quality and cost effectiveness of using fertilizer and/or alfalfa to improve meadow bromegrass pastures
Authors: Kopp J. C. , McCaughey W. P. , Wittenberg K. M.
Published: April 2011

A 4-yr study was conducted to determine the effects of forage type and fertilization on yield and quality of dryland pastures on the Canadian prairies. Pastures contained either meadow bromegrass (Bromus biebersteinii Roem & Schult.) (G) or alfalfa (Medicago sativa L.)-meadow bromegrass (A) and were either unfertilized (U) or fertilized (F) in order to increase the availability of essential plant nutrients to recommended levels. Average pasture yields (1995–1998) of AF, AU, GF and GU treatments were 3.88, 3.12, 3.95 and 1.94 ± 0.19 t DM ha-1 and average carrying capacities were 200.4, 163.9, 208.7 and 127.6 ± 3.3 cow-days ha-1, respectively. Alfalfa content declined (P < 0.05) over the 4 yr from 75.4 and 84.1% in 1995 to 32.5 and 40.3% in 1998 for AF and AU pastures, respectively. Simple incorporation of alfalfa into grass pastures (AU) improved carrying capacity by 28% and met the nutritional requirements of lactating beef cows at no additional cost. Fertilization of meadow bromegrass pastures (GF) improved the carrying capacity by 64% and met the nutrient requirements of lactating beef cows. Incorporating alfalfa with fertilization (AF) improved carrying capacity of pasture by 57% and met the nutrient requirements of lactating beef cows. Both the AF and GF treatments entailed significant financial risk as they were only cost-effective strategies when precipitation was not limiting. The AU treatment did not entail financial risk and was always a cost-effective treatment. Key words: Alfalfa, meadow bromegrass, productivity, forage quality, grazing
Effect of feeding different physical forms of diets on performance and carcass traits of goats
Authors: Goonewardene L. A. , Suleiman A. , Okine E. K.
Published: April 2011

Feding different physical forms of diets on performance and carcass traits of goats was studied. Thirty-six wethers were fed total mixed diets of either whole or rolled barley mixed with grass-alfalfa hay either chopped to 2.5 or 5 cm lengths. No differences (P > 0.05) in ADG (76.6 to 84.8 g d-1), feed intake (0.92 to 1.01 kg d-1), F:G (12.2 to 13.1 kg kg-1), hot carcass weight (13.5 to 14.1 kg), dressing %, (45.0 to 45.7%) and ribeye area (10.9 to 13.1 cm2) were observed among goats fed the four dietary combinations. Key words: Processing, feeds, goats, performance, carcass
Effect of injecting gonadotrophins during the luteal phase of the estrous cycleon the inter-estrus interval of gilts
Authors: ten Haff W. , Thacker P. A. , Kirkwood R. N.
Published: April 2011

Thirty gilts were assigned to receive no hormone injection (Group 1), an injection of 400 IU eCG plus 200 IU hCG (Group 2), or 750 IU eCG followed 78 h later by 500 IU hCG (Group 3). The average inter-estrus intervals were 21, 26, and 32 d for groups 1, 2 and 3, respectively. Cystic-like follicles (>15 mm) were observed in two group 2 gilts, and five group 3 gilts. One group 1gilt had a follicle of 18 mm. All other control gilt ovaries were grossly normal. The induction of cystic-like follicles would appear to preclude the commercial application of gonadotrophins during the luteal phase for extending the inter-estrus interval in gilts. Key words: Gonadotrophins, inter-estrus interval, gilts
Effects of storage time and exogenous xylanase supplementation of new season wheats on the performance of young male pigs
Authors: Cadogan D. J. , Choct M. , Campbell R. G.
Published: April 2011

A series of experiments was conducted to investigate the influence of new season wheats on pig growth performance. Experiments were carried out on 10 different wheats at the time of harvest and 10 mo post-harvest. At harvest wheat, at a 65% level in the steam-pelleted diets, influenced (P < 0.01) feed intake and daily gain over a 21-d trial. Thus, feed intake and daily gain of pigs offered the lowest and highest quality wheats varied by 47 and 48%, respectively. There was, however, no effect on feed conversion ratio (FCR), even though dry matter (DM) digestibility and digestible energy (DE) values of different wheats differed significantly (P < 0.01 and P < 0.01, respectively). The non-starch carbohydrate (NSC) level of the wheats was measured as the sum of non-starch polysaccharides (NSP) and free sugars. The NSC level of the wheats negatively affected feed intake (r2 = -0.556: P < 0.01) and daily gain (r2 = -0.574: P < 0.01). After 10 mo of storage, the feed intake and daily gain of the pigs fed the same wheats were significantly (P < 0.01) higher, but not all the wheats responded to storage. A xylanase product was added to three of the 10 mo-old wheats, which were pre-characterized as low, medium and high intake wheats. The enzyme increased (P < 0.01) daily gain and feed intake of the pigs fed the low-quality wheat by 50.6 and 42.8%, respectively. It may be concluded that the nutritive value of wheat for weaner pigs varies widely and appears to be related to the level of NSC and the cell wall structure of the grain. Key words: Wheat, non-starch polysaccharides, non-starch carbohydrate, xylanase, pigs
Hormonal, behavioural and performance characteristics of Meishan sows during pregnancy and lactation
Authors: Farmer and S. Robert C.
Published: April 2011

Meishan sows are known for their high prolificity and great lactational performances. Specific breed characteristics in terms of their embryonic, foetal and placental developments as well as their differences in mammary development at the end of gestation are covered. The various known metabolic, physiological and endocrine factors related to the decreased embryonic mortality and increased placental vascularity, which are largely responsible for the greater litter size of Meishans, are discussed. An overview of published data on the endocrine status of the sow and foetuses throughout pregnancy is also presented. The superiority of Meishan sows during lactation is described in terms of its various components (i.e., piglet growth and development, sow and litter behaviour, milk composition) and the breed differences pertaining to sow metabolism and endocrinology during lactation are covered in order to provide an insight as to the possible mechanisms responsible for these superior performances. This review illustrates how a better understanding of the biological differences between Meishan sows and sows from European breeds could benefit the development of new management schemes to further improve reproductive potential of sows from traditional breeds. Key words: Meishan, gestation, lactation, hormones, behaviour, performance
Vaccination against follistatin and the effect on ovulation rate in estrus-induced gilts
Authors: Christensen C. R. , Redmond M. J. , Laarveld B.
Published: April 2011

Primiparous sows were vaccinated against follistatin to determine the effect on ovulation rate following typical commercial estrus induction and synchronization. Seventy-five gilts received four vaccinations against a recombinant porcine follistatin (FS) or a sham vaccine (CTL). At 85 kg, gilts were induced into estrus with a combination of PG600 and hCG and synchronized using PGF2α. At the second estrus, antibody titers ranged from 0 to1:6400 in the FS-vaccinated treatment group and no FS antibodies were detected in the CTL group. Late in the second subsequent luteal phase the reproductive tracts of the gilts that had displayed two estruses were collected. There was no significant difference in the number of corpora lutea (FS = 13.2 ± 0.5, CTL = 14.5 ± 0.7) or corpora albicantia (FS = 12.1 ± 1.9, CTL = 12.3 ± 2.0) between treatments. Follistatin-vaccinated gilts displayed an increased number of luteal structures which resembled corpora hemorrhagica (P = 0.04). This study shows that vaccination of gilts against FS concurrent with estrus induction and synchronization affected ovarian morphology, although an effect on ovulation rate was not apparent. Key words: Swine, follistatin, immunoneutralization, fecundity, ovulation rate
Effect of variety and maturity stage on chemical composition, carbohydrate and protein subfractions, in vitro rumen degradability and energy values of timothy and alfalfa
Authors: Yu P. , Christensen D. A. , McKinnon J. J. , Markert J. D.
Published: April 2011

The objective of this study was to investigate the effects of forage variety and stage of maturity on chemical composition, protein and carbohydrate subfractions, in vitro rumen degradability and energy content under the climatic conditions of western Canada. Two varieties of alfalfa (Medicago sativa L. cvs. Pioneer and Beaver) and timothy (Phleum pratense L. cvs. Climax and Joliette), grown at three locations in Saskatchewan (Canada), were cut at three stages [1 = 1 wk before commercial cut (early bud for alfalfa; joint for timothy); 2 = at commercial cut (late bud for alfalfa; pre-bloom head for timothy); and 3 = one week after commercial cut (early bloom for alfalfa; full head for timothy)]. The results showed that: (1) the varieties had minimal effects on nutritional value; however, (2) stage of cutting had a large impact on chemical composition, protein and carbohydrate fractions, in vitro rumen degradability and energy value. As plant maturity advanced from stage 1 to 3, the following changes were noticed: (a) CP was decreased [alfalfa: 20.2 to 17.6; timothy: 11.1 to 7.9% dry matter (DM)]; fibre was affected very little in alfalfa but increased in timothy [acid detergent fibre (ADF): 38.0 to 40.7; neutral detergent fibre (NDF): 68.7 to 72.8% DM]; lignin and neutral detergent insoluble protein (NDIP) were not affected in either forage; acid detergent insoluble protein (ADIP) was increased in alfalfa (3.5 to 17.1% CP), but no effect was seen in timothy; (b) the rapidly degradable protein fraction (PA) was reduced in alfalfa (51.2 to 34.8% CP) but increased in timothy (9.2 to 27.5% CP); the rapidly degradable fraction (PB1) increased in alfalfa (0.0 to 25.2% CP), but decreased in timothy (31.6 to 16.7%); the intermediate degradable fraction (PB2) decreased in both forages (alfalfa: 14.1 to 5.2; timothy: 37.8 to 29.4% CP); the slowly degradable fraction (PB3) declined in alfalfa (33.1 to 17.7% CP), but was not affected in timothy (averaging 21.3% CP); the unavailable fraction (PC) associated with the cell wall increased in alfalfa (3.5 to 17.1% CP), but did not change in timothy (averaging 5.2% CP); (c) in vitro rumen degradabilities of DM (IVDMD) and NDF (IVNDFD) increased at stage 2 and then declined at stage 3. The highest IVDMD and IVNDFD after a 48-h incubation were at cutting stage 2 (50.5 and 37.3%; 42.8 and 37.3% for alfalfa and timothy, respectively); (d) the energy content behaved in a quadratic fashion; it increased initially and then decreased with the highest energy contents at stage 2 for both forages (TDN1x, DE1x, DEp, MEp, NELp: 63.8% DM, 2.92, 2.68, 2.26, 1.40 Mcal kg-1 DM for alfalfa; 45.3% DM, 2.03, 1.86, 1.43, 0.82 Mcal kg-1 DM for timothy, respectively). In general, the best cutting was found at stage 2, which was late-bud for alfalfa varieties and pre-bloom head for timothy. Key words: Alfalfa, timothy, variety, maturity, nutritive value
Conservation of fresh ram spermatozoa at 5°C in the presence of seminal plasma
Authors: Morrier A. , Castonguay F. , Bailey J. L.
Published: April 2011

Seminal plasma aids sperm transport and contains factors beneficial for sperm function. In artificial insemination, however, diluting the semen reduces the concentration of seminal plasma. To test the hypothesis that supplemental seminal plasma in extended ram semen improves conservation at 5°C, we added various concentrations of seminal plasma to semen during storage, and investigated subsequent sperm function in vitro. Semen was divided into three aliquots, extended in a commercial diluent (Triladyl) supplemented with 0, 10 or 25% (vol:vol) ovine seminal plasma and cooled to 5°C. After 8 and 24 h at 5°C, sperm were suspended in a modified synthetic oviduct fluid (SOF-m) at 39°C to mimic the female genital tract at insemination. Sperm aliquots were assessed for motility and chlortetracycline fluorescence after 0, 4 and 8 h in the SOFm. No significant differences were observed due to seminal plasma supplementation during conservation at 5°C or incubation in SOF-m at 39°C. However, decreased sperm motility and fewer non-capacitated sperm were observed concomitant with an augmentation of capacitated and acrosome-reacted cells during incubation in SOF-m. Therefore, the hypothesis that diluent supplementation with homologous seminal plasma improves ram sperm conservation or subsequent sperm function was not supported. Key words: Ovine, ram, sperm, motility, viability, chlortetracycline fluorescence, artificial insemination, SOF
Responses of the bovine mammary glands to absorptive supply of single amino acids
Authors: Cant J. P. , Berthiaume R. , Lapierre H. , Luimes P. H. , McBride B. W. , Pacheco D.
Published: April 2011

In this review, we discuss the mechanismsof responses of various tissues of the lactating dairy cow, particularly the mammary glands, to perturbations in supply of single amino acids that result in observed milk protein yields. Additions of methionine, lysine, histidine or leucine to the absorptive supply cause arterial concentrations of these amino acids to increase, mammary extractions to drop and mammary blood flow to decrease. Single subtractions of essential amino acids have the opposite effect. Changes in mammary blood flow that have been recorded can be explained as attempts by the mammary glands to restore intracellular ATP balance in the face of altered concentrations of energy metabolites in the general circulation. In a quantitative sense, milk protein yield is relatively insensitive to fluctuations in arterial amino acid concentrations but can be stimulated by any one of a number of amino acids. In this context, it is suggested that the designation of a limiting amino acid is not appropriate to the purpose of predicting milk protein yield. Rather, milk protein synthesis appears to operate at a predetermined rate set by external communications of milk withdrawal rate, physiological state and overall nutritional status. Utilization of amino acids (AA) by splanchnic and peripheral tissues, in coordination with the mammary setpoint, offsets imperfections in the dietary AA supply. How strongly an individual AA influences the mammary setpoint, arterial concentrations of energy metabolites, and mammary AA transport capacity will determine the magnitude of the milk protein yield response when its absorptive supply is changed. Key words: Dairy cows, milk protein, amino acid
Regulation of LH secretion during seasonal anestrus by dopaminergic pathways in Rasa Aragonesa ewes treated or not with melatonin
Authors: Forcada F. , Abecia J. A. , Zúñiga O.
Published: April 2011

The involvement of the dopaminergic system in the steroid-dependent inhibition of luteinizing hormone (LH) secretion during anestrus in ovariectomized, estradiol-implanted adult Rasa Aragonesa ewes was investigated in both ewes treated with melatonin on 8 March (n = 10) and in control (n = 8) ewes. Melatonin implants did not significantly increase LH secretion. However, treatment with pimozide induced a significant increase (P < 0.05) in LH pulse frequency in both groups during early anestrus. We conclude that, in the absence of males, the dopaminergic system is clearly involved in the inhibition of LH secretion during anestrus in both melatonin-treated and control ewes. Key words: Sheep, melatonin, pimozide
Photoperiod effects on the development of beef heifers
Authors: Small J. A. , Glover N. D. , Kennedy A. D. , McCaughey W. P. , Ward D. R.
Published: April 2011

Crossbred beef heifers (n = 144) were assigned at weaning (187 ± 14 d of age) by body weight (225 ± 23 kg) and sire breed (British/Continental) to one of two photoperiod treatments from 21 Decem ber 1998 (0 wk) until 10 May 1999 (20 wk): natural photoperiod (NP) that gradually increased from 8.1 h (0 wk) to 15.2 h (20 wk) and, extended photoperiod (EP) that consisted of natural + supplemental light (400 lx, 1 m above ground) to extend photoperiod to 16 h. Rations were formulated for two-steps of body weight gain (0.6 and 1.2 kg d-1) to achieve 60% of mature weight at 18 wk. Visual observations of estrus behavior were made twice daily and confirmed by serum progesterone. Body weight, backfat and serum prolactin data were determined for each 4-wk period. Ambient temperatures averaged -12.2 ± 6°C in winter (0 to 12 wk) and 4.2 ± 5°C in spring (12 to 20 wk). Gain in body weight was greater (P < 0.05) and backfat lower (P < 0.05) for EP than NP treatments from -2 to 6 wk and only 1% of heifers had attained puberty during this period. However, as yearlings at similar (P > 0.05) body weight and backfat, more (P < 0.05) EP than NP heifers had attained puberty (84.7% vs. 69.4%). Prolactin was greater (P < 0.05) for EP than NP treatments from 2 to 6 wk (10.3 vs 5.5 ± 1.2 ng mL-1). Management of photoperiod influences attainment of puberty and prolactin secretion in beef heifers housed in an outdoor environment. Key words: Photoperiod, puberty, estrus, beef heifers, prolactin
Feeding value of peas for backgrounding beef heifers
Authors: Chen J. -Q. , Okine E. K. , Price M. A. , Khorasani G. R.
Published: April 2011

Four diets in which peas progressively replaced barley [0% (0P), 30% (30P), 50% (50P), and 100% peas (100P)] and one in which canola meal (CM) replaced 10% of the barley, were fed to 90 beef heifers (initial weight 215.8 ± 13.8 kg). The heifers achieved average daily gains (ADGs) of 0.72, 0.80, 0.79, 0.83, and 0.76 kg d-1 on the five diets, respectively, with the difference between the 0P group and the 100P group being significant (P = 0.028). The total feed costs of gain were $0.786, 0.779, 0.799, 0.860, and 0.817 kg-1 for the five groups, respectively, with the cost of gain being significantly greater (P < 0.05) for the 100P group than for the 0P, 30P or 50P groups. The latter three were not significantly different from each other. Three rumen-cannulated steers (575 ± 56.3 kg) were used to estimate the degradability of the dry matter (DM) and N in the barley straw (BS), CM, barley grain (BG) and peas used in the feeding trial. The rumen undegradable protein (RUP) levels supplied by the five diets were 17.5, 19.0, 19.9, 21.5, and 22.5%, respectively, and all of them met the requirements of these cattle. The RUP content of peas ground through a 1-mm screen was lower than that of peas ground through 2- or 4-mm screens (P < 0.01), which were themselves not significantly different from each other (P = 0.67). The low RUP content of peas was not a limiting factor for growth in backgrounding cattle. Key words: Cattle, field peas, dry matter intake, feed conversion efficiency, rumen me
Grazing behaviour and weight change of cattle turned out to pasture in spring
Authors: Charmley E. , Jannasch R. W. , Boyd J.
Published: April 2011

In the first of two trials, 20 Hereford steers were allocated to two adjacent 1.6-ha pastures on 29 May 1996. Steers in one pasture were given no supplement, while those in the other received supplemental silage each day. All steers on each treatment grazed their allocated paddock continuously for 28 d. Steers on pasture were weighed and their behaviour was monitored periodically throughout the 4 wk of grazing. The dry matter (DM) availability at turnout (651 kg hd-1) was considered in excess to requirement, since neither availability nor sward height declined over 28 d. In spite of this, steers lost 15 kg after turnout and took 12 d to regain their initial weight. There were no treatment effects. Nutrient composition of the sward changed in accordance with advancing maturity. Percent of time observed grazing (51%) did not change over the 28-d period; however, rumination time increased from around 10 to 30%. Grazing behaviour was similar for steers on both treatments. Silage intake averaged only 1.3 kg DM hd-1d-1. In 1997, 28 yearling steers were used in a 2 × 2 factorial design to study the effect of turnout date to pasture [21 May (E) vs. 4 June (L)] and supplemental silage feeding on weight change, grazing behaviour, pasture productivity and forage quality over 28 d. The DM availability at turnout was 391 kg hd-1. Available DM and sward height declined in both early and late treatments after turnout. The early group had to be removed from the trial after 16 d when sward height dropped below 4 cm. Sward quali ty after turnout declined only for the late group. Loss of body weight (BW) and days to regain initial BW after turnout were greater for early versus late steers. Steers ate only 0.5 kg silage DM hd-1d-1, but this reduced weight loss in late steers. Cattle turned out later spent less time grazing (P < 0.001 at 5 and 14 d) but no less time ruminating. Transient weight loss associated with turnout to pasture cannot be wholly explained by behavioural patterns. Other factors, such as altered ruminal conditions, must also play an important role. Key words: Pasture, steer performance, grazing behaviour, weight change
Past, present and future perspectives on sexing sperm
Authors: Garner D. L. , Seidel Jr. G. E.
Published: April 2011

Development of flow cytometry for sorting mammalian sperm according to their sex chromosomes began in the late 1970s and early 1980s. This technology, which has recently been commercialized for bovine sperm, is based on the differences in DNA content between X- and Y-chromosome-bearing sperm. Under ideal conditions, 5000 live bovine sperm of each sex can be sorted per second at 90% accuracy. Pregnancy rates of 50% have been achieved routinely in well-managed heifers with sex-sorted, cryopreserved bovine sperm compared to 60–80% with unsexed control sperm. About 90% of offspring have been of the selected sex. Sorting sperm according to sex chromosome content is similarly successful in many other mammals including exotic species, but sorting efficiencies are somewhat less for sperm from some species. Key words: Mammals, sex chromosomes, flow cytometer, cell sorter, DNA content, X and Y sperm, Hoechst 33342
Dairy genetic improvement through artificial insemination, performance recording and genetic evaluation
Authors: Van Doormaal B. J. , Kistemaker G. J.
Published: April 2011

Artificial insemination (AI) of dairy cattle in Canada was started more than half a century ago and today it is estimated that at least 75% of all dairy cattle nationally are bred using this common reproductive technology. A Best Linear Unbiased Prediction sire model for estimating genetic evaluations for production traits was introduced in 1975. The combination of extensive use of AI with genetic evaluations for bulls and cows has resulted in significant phenotypic and genetic gains over the past 20 yr. In the Holstein breed, mature equivalent yields have increased by an average of 200 kg milk, 7.0 kg fat and 6.3 kg protein per year since 1980. Genetically, the relative emphasis realized for production traits versus overall type during the past 5 yr has followed the 60:40 breeding goal represented in the Lifetime Profit Index, which has increased at an average rate of 0.28 standard units per year. Examination of the generation interval in the Canadian Holstein breed, associated with each of the four pathways for genetic improvement, indicates a 46% increase in the rate of annual genetic gain today compared to 20 yr ago. The increased accuracy and intensity of selection associated with the use of AI and genetic evaluations have also contributed to the rates of phenotypic and genetic progress achieved over the years. In the future , AI will continue to be a critical component of the genetic gains possible in dairy cattle breeding but it will be complemented by other reproductive technologies aimed at further reducing generation intervals and increasing the accuracy and selection of intensity, especially on the female side. Key words: Dairy cattle, artificial insemination, genetic progress, genetic evaluation
Total antioxidant capacity: A tool for evaluating the nutritional status of dairy heifers and cows
Authors: Mandebvu P. , Castillo J. B. , Steckley D. J. , Evans E.
Published: April 2011

The nutritional status of dairy heifers and cows in Nova Scotia and Ontario was evaluated by measuring the total antioxidant capacity (TAC) of plasma antioxidants. Lactating cows had higher TAC levels compared to dry cows (P < 0.005). The TAC levels in cows were higher in Ontario compared to Nova Scotia (P < 0.001), and varied with changes in seasons, being highest in winter and summer in Nova Scotia and highest in the fall and spring in Ontario (P < 0.001). Key words: Antioxidant, dairy heifer