bluuebunny/crossref_metadata_2025 huggingface dataset:
Do windbreaks minimize stress on cattle grazing foothill winter range?
Authors: Olson B. E. , Wallander R. T. , Paterson J. A.
Published: March 2010

Cattle often graze foothill rangelands in northern latitudes as a cost-effective alternative to being fed hay. In a 2-yr study, we determined whether exposure to winter wind elicits a stress response in pregnant cows (5–7 yr old) grazing a foothill rangeland. We measured several indicators of stress-response of cows which had (windbreak) or did not have (non-windbreak) access to windbreaks. In Winter 1 (1966–1997), backfat thickness increased on windbreak and non-wind-break cattle. Body condition scores of both groups were lower at the end of the trial. In Winter 2 (1997–1998), backfat thickness decreased for windbreak and non-windbreak cattle. Body condition scores did not change. Weight changes were minor both winters. Changes in backfat thickness indicated that cattle in Winter 1 were catabolizing more lean muscle tissue, whereas cattle in Winter 2 were catabolizing more fat. Cattle entered Winter 1 in lower body condition and mass than in Winter 2. Cattle with access to windbreaks tended to have a stronger cell-mediated immune response than non-windbreak cattle. Birth and weaning weights of calves, and calving interval were similar for windbreak and non-windbreak cattle. Neither winter elicited a strong stress response from cattle grazing this foothill rangeland, with or without access to windbreaks. Key words: Beef cattle, backfat, body condition, weight loss, immune response
Determination of sample size for testing associations between genetic markers and quantitative traits in trait-based analysis
Authors: Lin C. Y.
Published: March 2010

A general formula for computing the required sample size for DNA genotyping was developed for between-population sampling schemes (control vs. selected lines in one-way selection) and within-population sampling schemes (two-tail sampling, tri-sampling or multi-sampling). In DNA fingerprinting (presence or absence of a band), the minimum sample size required for detection of marker-trait association depends upon three factors: 1) the level of significance (α = 0.05 or 0.01) and degrees of freedom for χ 2 values: a higher level of significance and a greater d.f. needs a greater sample size; 2) the sum of squares in marker frequencies between groups: a greater sum of squares requires a smaller sample size; and 3) the product of [Formula: see text], where [Formula: see text] is the average of marker genotypic frequencies among groups. The product is maximum when [Formula: see text]. A larger product requirse a greater sample size. The proposed tri-sampling allows for the detection of gene action of the linked QTL, but requires a larger sample size than two-tail sampling. Detection of non-additive gene action requires a smaller sample size than the detection of additive gene action in tri-sampling scheme. The required sample size increases rapidly with increasing number of groups sampled in trait-based analysis. The required sample size is also derived for RFLP genotyping of a diallelic locus (three marker genotypes: +/+, +/−, and −/−) and a multiallelic locus. The restriction fragment length polymorphism (RFLP) genotyping requires a smaller sample size than DNA fingerprinting for detection of marker-QTL association. Key words: Sample size, genetic markers, trait-based analysis
Effect of Tween 80 and salinomycin on ruminal fermentation and nutrient digestion in steers fed a diet containing 70% barley
Authors: Hristov A. N. , McAllister T. A. , Olson M. E. , Cheng K.-J. , Yanke L. J. , Shelford J. A.
Published: March 2010

Ten Jersey steers (484 ± 55 kg) were fed a basal diet of 70% rolled barley grain and 30% alfalfa silage [dry matter (DM) basis] with or without additives, in a replicated 5 × 5 Latin square experiment. Treatments (additives per kilogram dietary DM) were: C, no additives (control); T, Tween 80 (2 g kg−1); SH, salinomycin (13 mg kg−1); TSM, Tween 80 (2 g kg−1) plus salinomycin (6.5 mg kg−1); and TSL, Tween 80 (2 g kg−1) plus salinomycin (3.25 mg kg−1). Ruminal pH, concentrations of ammonia, total free amino acids, reducing sugars and total volatile fatty acids (VFA), and fluid phase viscosity were unaffected (P > 0.05) by treatment. Ruminal carboxymethylcellulase, xylanase and amylase activities, numbers of protozoa, and outflow rates of the liquid and solid phases of ruminal contents did not differ (P > 0.05) among treatments. Ruminal lactic acid bacteria populations tended (P < 0.1) to be smaller with SH compared with C, but counts were unaffected (P > 0.05) by T, TSL and TSM. Partitioning of ruminal digesta and microbial protein flow were similar (P > 0.05) among treatments. Compared with C, the ruminal rate of degradation (in situ) of alfalfa DM tended to be higher (P < 0.10) with SH, and the rate of barley grain DM degradation was higher (P < 0.05) with T. Intake and apparent digestibilities of DM, neutral detergent fibre (NDF), acid detergent fibre (ADF) and crude protein were unaffected (P > 0.05) by treatment, as were blood glucose and urea levels. Tween 80 and salinomycin did not affect ruminal fermentation or nutrient digestibility in steers fed a barley grain/alfalfa silage diet. Key words: Tween 80, salinomycin, ruminal fermentation, digestibility, steer
Dealing with antimicrobial resistance – the Danish experience
Authors: Bager F. , Aarestrup F. M. , Wegener H. C.
Published: March 2010

Following the discovery in 1994 and 1995 that use of the glycopeptide antimicrobial avoparcin for growth promotion was associated with the occurrence of vancomycin resistant Enterococcus faecium in food animals and in food, the Danish Minister of Food, Agriculture and Fisheries banned the use of avoparcin in May 1995. The ban was later extended by the European Commission to include all EU member states. In May 1999, the EU Scientific Steering Committee recommended that use for growth promotion of antimicrobials, which are or may be used in human or veterinary medicine should be phased out as soon as possible and ultimately abolished. During the first half of the 1990s the consumption of tetracyclines, mainly in pig production, increased markedly. This was countered by severely reducing through legal means the financial enticement for veterinarians to prescribe medicines and by restricting the availability of tetracycline as non-registered speciality products. The focus on consumption of antimicrobials and on resistance prompted a number of initiatives by Danish authorities to limit the increase in antimicrobial resistance. One such initiative was the implementation of an integrated programme (DANMAP), which monitors resistance among bacteria from food animals, food and humans. A programme to monitor all use of prescription medicine in food animals at the herd level is presently being implemented. Another initiative was the elaboration of a series of practical recommendations to veterinarians on the prudent use of antimicrobials in order to reduce the development of resistance without compromising therapeutic efficacy. Our experience with avoparcin shows that a restrictive policy on the use of antimicrobials can curb the development of resistance. However, the occurrence and persistence of specific resistance phenotypes is the end-result of complex interactions of, among others, antimicrobial co-selection, clonal spread of resistant strains and various herd management factors. Key words: Antimicrobial resistance, Denmark, avoparcin, tetracycline
Electronic identification: Applications in beef production and research
Authors: McAllister T. A. , Gibb D. J. , Kemp R. A. , Huisma C. , Olson M. E. , Milligan D. , Schwartzkopf-Genswein K. S.
Published: March 2010

Individual identification of beef cattle is not new to the Canadian beef industry, as traceback systems played a pivotal role in the eradication of bovine tuberculosis in the 1940s and 1950s and brucellosis in the 1970s and 1980s. Recent concerns over animal health (e.g., bovine spongiform encephaolopathy), export markets, product consistency, meat quality (e.g., tenderness, marbling) and safety (e.g., Escherichia. coli 0157:H7, Salmonella spp.) make reestablishment of a traceback system a logical approach to assuring consumer confidence in Canadian beef. Originally, simple Kurl-lockTM ear tags with a unique number were used to trace individuals back to their herd of origin. Although useful for addressing disease concerns, this system did not lend itself to compiling additional information (e.g., growth performance, animal health, breeding programs, carcass quality) for use in management or marketing decisions. More sophisticated electronic identification systems can readily interface with computers and make information management an even more pivotal component of beef production. Several electronic identification systems (e.g., bar codes, radio frequency identification, read–write systems) are being assessed for their effectiveness for identifying individual cattle under production conditions. In research applications, this technology has the potential for individual animals to become the experimental unit under group housing conditions. By combining electronic identification technology with devices that measure physiological (e.g., temperature, pH, body weight, feed intake) parameters, researchers will be able to collect data in natural production environments that were previously only obtainable under controlled experimental conditions with a limited number of animals. Key words: Electronic identification, beef, traceback, radio frequency identification
Reproductive performance and uterine prostaglandin secretion in gilts conditioned with dead semen and receiving dietary supplements of folic acid
Authors: Giguère A. , Girard C. L. , Lambert R. , Laforest J. P. , Matte J. J.
Published: March 2010

The effects of dietary supplements of folic acid at 0 (F−) or 15 ppm (F+) and of conditioning the uterus (C+) or not (C−) with an intrauterine infusion of dead semen on embryonic survival and prostaglandin E2 (PGE2) concentrations in the allantoic fluid on day 30 of gestation were studied. Sixty-four F1 crossbred gilts (Yorkshire × Landrace) were used in a 2 × 2 factorial design. The initiation of folate supplementation and the intrauterine infusion of dead semen were done at the estrus preceding the fertile mating. Folate status in serum was lower in F+ gilts than in F− gilts during the estrus cycle (folic acid × period interaction, P ≤ 0.007). Conditioning increased ovulation rate in F− gilts while it tended to decrease it in F+ gilts (interaction folic acid × conditioning, P ≤ 0.03). A similar interaction (P ≤ 0.02) was observed on the number of presumably live embryos at 30 d of gestation. Mean PGE2 concentration in the allantoic fluid was not affected by treatments (P ≥ 0.44), but the frequency of sows having elevated allantoic PGE2 (> 4 ng mL−1) tended to be higher (P ≤ 0.06) in F+ sows. Overall values of PGE2 were correlated with total litter weight (R2 = 0.54). In conclusion, there was no synergism between folic acid supplements and conditioning of the uterus with dead semen on the reproductive performance or on the secretion of allantoic PGE2 at 30 d of gestation. The secretion of allantoic PGE2 appears as an important factor involved in the control of litter size and weight. Key words: Folic acid, artificial insemination, semen, gilts, conditioning, embryo mortality
Vaccination against follistatin affects reproductive potential in cycling gilts
Authors: Christensen C. R. , Redmond M. J. , Laarveld B.
Published: March 2010

Primiparous sows (gilts) were actively vaccinated against follistatin in an attempt to modify litter size. Forty-seven gilts were vaccinated four times against a recombinant porcine follistatin (FS) or a sham vaccine (CTL) and were allowed to mature naturally prior to breeding. At breeding, FS antibody titers ranged from 0 to 1:6400 in the FS vaccinated gilts, and were not detectable in the CTL gilts. Overall, follistatin vaccination did not affect the total number of pigs born live (FS = 10.9 ± 0.5, CTL = 10.3 ± 0.4), stillborn (FS = 0.4 ± 0.1, CTL = 0.4 ± 0.2) or mummified (FS = 0.1 ± 0.1, CTL = 0.3 ± 0.1). However, separation of the FS vaccinated gilts into low (≤1:400, n = 16) and high (>1:400, n = 7) titer groups revealed significant differences in piglets born alive (FS high titer = 12.9 ± 0.9, FS low titer = 10.0 ± 0.5: P = 0.01) and total number of piglets born (FS high titer = 13.0 ± 0.8, FS low titer = 10.8 ± 0.6: P = 0.08). This study shows that vaccination of gilts against follistatin increased litter size in those gilts which achieved a high antibody titer to follistatin. Key words: Swine, follistatin, immunoneutralization, fecundity, litter size
Seasonal energetic parameters of free-grazing bison (Bison bison)
Authors: Rutley B. D. , Hudson R. J.
Published: March 2010

Seasonal energetic parameters of yearling bison were estimated using the bite-count and single marker methods (fieldtrials) during each solstice and equinox between June 1994 and December 1995. To calibrate the marker method and to provide a controlled estimate of seasonal requirements, balance trials were conducted in metabolism crates during winter solstice 1994 and summer solstice 1995 (pen trials). In pen trials, actual metabolizable energy (ME) intake was lower (P < 0.01) during winter (528 ± 51 kJ W−0.75 d−1) than in summer (917 ± 69 kJ W−0.75 d−1). Similarly, in field trials, estimated ME intakes were lower for both bite count (P < 0.01) and marker methods (P < 0.05) during winter (819 ± 375, 146 ± 105 kJ W−0.75 d−1) than summer (1977 ± 186, 408 ± 53 kJ W−0.75 d−1), respectively. Estimated ME requirements (actual intake, pen trials) were 532 ± 178 kJ W−0.75 d−1 in winter and 956 ± 107 kJ W−0.75 d−1 in summer. In field trials, estimated ME requirements (marker method) ranged from 146 ± 22 kJ W−0.75 d−1 (December 1994) to 478 ± 45 kJ W−0.75 d−1 (June 1995). Seasonal variation (P < 0.05) in total digesta turnover time (46.4 ± 1.4 h, December 1994; 24.9 ± 2.7 h, June 1995) was related more consistently to seasonal differences in transit time (18.2 ± 1.2 h, 4.0 ± 0.8 h, respectively) than differences in reticulo-rumen and lower tract turnover time. Bison exhibited strong seasonal differences in energetic parameters like other northern wild ruminants. Key words: Bison, seasonality, metabolizable energy requirements, intake, excretion parameters, grazing
The effects of bull exposure and lasalocid on the development of replacement beef heifers
Authors: Small J. A. , Vecchio R. P. Del , McCaughey W. P. , Ward D. R. , Sutherland W. P.
Published: March 2010

At weaning in the fall, crossbred heifers (n = 224), born in either the winter (January–February) or spring (March–April), were assigned on the basis of age, sire-breed and body weight to one of two similar winter housing facilities (with or without sterilized bulls), and to one of two forage-based (87%) diets (with or without lasalocid, 200 mg d−1) within each housing facility. Observations for estrus were made twice daily. Timed AI (66 h after PGF2α) was used to breed heifers for the first time at 14 mo of age. Plasma progesterone concentrations were used to confirm estrus/ovulation and to determine the PGF2α response rate. Bull exposure advanced puberty in winter-born heifers, but delayed puberty in spring-born heifers (P ≤ 0.029). Similarly, timed AI pregnancy for winter-born heifers was higher with than without bull exposure (58.9 vs. 32.5 ± 5.3%; P = 0.017) while the opposite occurred for the spring-born group (27.1 vs. 59.1 ± 4.7%; P < 0.001). Bull-exposed spring-born heifers were the oldest at calving, the latest to calve, and their calves had the slowest growth and lowest weaning weight means (P < 0.027). Lasalocid did not influence puberty (P ≥ 0.273), had a small effect on body weight gain (P ≥ 0.033) that did not limit attainment of optimal body weight or condition at AI, but enhanced response rate for spring-born heifers (P = 0.075) and conception rate for winter-born heifers (P = 0.047). The efficacy of bull exposure and lasalocid is dependent upon the proximity of heifers to the attainment of puberty when the treatments are introduced; further research is required to determine the most appropriate use of either management tool for developing beef replacement heifers. Key words: Puberty, heifer development, bull exposure, ionophore, estrus, conception
Nutritional performance of calves fed milk replacers containing processed soybean products
Authors: Mir P. S. , Burton J. H. , Buchanan-Smith J. G.
Published: March 2010

Calves in three age groups were fed milk replacers containing skim milk (SMP) or with 43% of the protein substituted by one of heated soybean meal (HSBM(commercial soybean meal)); extruded soybean meal (ExSBM); ethanol-extracted soybean meal (EtSBM); or fermented soybean meal (FSBM) to determine effects on weight gain, feed and protein efficiency and fecal dry matter. Experimental milk replacers were introduced to calves at 6, 18 and 30 d of age for those in age groups 1, 2 and 3, respectively, and fed for 20 d. Even though dry milk replacer intake did not vary among calves fed the five replacers, weight gains of calves receiving either the SMP replacer (SMPR) or those containing the processed soybean meals ranged from 6.5 to 6.7 kg for the experimental period and were greater (P < 0.05) than the 3.4-kg weight gain of calves fed the HSBM containing replacer (HSBMR). Among the calves in age groups 2 and 3, weight gains of calves reared on the replacer containing FSBM, EtSBM or the SMPR were similar but greater (P < 0.05) than gains of calves on HSBMR. Calves in age group 2 receiving the ExSBM or FSBM containing replacers gained more weight than those receiving HSBMR. Both ExSBM and FSBM can be used in milk replacers for rearing calves older than 20 d of age. Key words: Extruded, fermented, soybean meal, calf milk replacer, nutritional performance, diarrhoea
A kinetic model of copper metabolism in lactating dairy cows
Authors: Buckley Wayne T.
Published: March 2010

A model of Cu metabolism in dairy cows was developed using a stable isotope, Cu-65, as an in vivo tracer. Copper-65 was administered intravenously to six dairy cows fed a diet of corn silage plus grain concentrate containing 10 mg Cu, 1.1 mg Mo and 2.2 g S kg−1 diet dry matter. The distribution of tracer and the natural concentration of Cu in liver, plasma and milk were monitored for 140 d (urine and feces for 5 and 7 d). A kinetic modeling program (SAAM/CONSAM) was utilized for development of the model. Seven compartments, including liver, two plasma compartments, remaining body, gut, milk (including udder) and feces were required to describe the experimental data. The model included five routes of Cu loss: biliary and nonbiliary fecal excretion, urinary excretion and two routes into the milk/udder compartment. The solution to the model indicated that 5.1 ± 1.5% (mean ± SD, n = 6) of dietary Cu was absorbed from the gut; 92.2 ± 5.0% of the absorbed Cu was removed directly by liver; 38.4 ± 13.3% of Cu leaving the liver entered the nondirect-reacting (NDR) Cu compartment of plasma; 80.7 ± 9.0% of NDR Cu entered the remaining body compartment while the balance of the NDR Cu supplied the milk/udder compartment. The transfer of Cu from liver to the NDR Cu in plasma appeared to be a point of metabolic control in Cu metabolism, and was represented in the model by an empirical nonlinear function. Key words: Copper, dairy, cow, modeling, isotope, metabolism
Arsanilic acid as a growth promoter for chicken broilers when administered via either the feed or drinking water
Authors: Proudfoot F. G. , Jackson E. D. , Hulan H. W. , Salisbury C. D. C.
Published: March 2010

Two thousand four hundred male broiler chicks were used in three experiments to evaluate the biological and economic effects of using arsanilic acid as a growth promoter. In two experiments four treatments were (A) control diets (CD); (B) CD plus 99 mg kg−1 arsanilic acid; (C) CD plus drinking water containing arsanilic acid calculated to achieve equivalent exposure to treatment B; and (D) same as treatment C except arsanilic acid concentration reduced by 50%. A third experiment evaluated the dietary addition of arsanilic acid at 0, 33, 66 and 99 mg kg−1. Arsanilic acid supplementation had no significant (P > 0.05) effect on mortality, feed conversion, final live body weights or monetary returns at slaughter age (42 d). Analysis of breast, thigh and liver tissues using method with a sensitivity of 0.02 mg kg−1 showed a significant increase in liver arsenic residues when supplemented diets were fed to slaughter age. Withdrawal of arsanilic acid from diets 7 d prior to slaughter returned the arsenic residues to normal background (control) levels. It is concluded that the use of arsanilic acid at dietary concentrations up to 99 mg kg−1 (the maximum permissible in Canada) was ineffective in improving either the biological or economic performance of broiler chickens. Key words: Arsanilic acid, growth promoter, broiler chickens
Effect of high levels of copper or dichlorvos during late gestation and lactation on sow productivity
Authors: Thacker P. A.
Published: March 2010

One hundred and eighty-five crossbred (Yorkshire × Landrace) sows of mixed parity were randomly assigned to be fed either a basal diet or the same ration top dressed with either 500 ppm dichlorvos, 250 ppm copper or a combination of these additives. Top dressing was conducted from the time the sows entered the farrowing crate on day 106 of gestation until they were weaned 28 d postpartum. There was no effect of treatment on the number of pigs born alive, born dead or their birthweight. However, preweaning mortality, based as a percentage of pigs found alive, was 20.3% for control sows, 13.8% for sows fed the ration top dressed with copper, 12.3% for sows fed the ration top dressed with dichlorvos and 10.6% for sows fed the ration top dressed with the combination of feed additives (P = 0.02). There was no significant effect of treatment on the percentage of fat, protein, lactose or total solids in sows milk. There was also no effect of treatment on lactation feed intake, sow weight loss through lactation, the interval between weaning and successful service, conception rate, serum copper levels or total cholesterol. HDL cholesterol levels, serum copper, zinc and iron levels were generally higher in piglets from treated sows than controls. It was concluded that feeding high levels of copper or dichlorvos, alone or in combination, during late gestation and lactation may be useful as a means of reducing preweaning mortality in baby pigs. However, the increased survival rate of baby pigs is unlikely due to alterations in the composition of sow's milk or milk yield. Key words: Sow, reproduction, copper, dichlorvos, milk
Effect of premating injections of insulin on fertility and prolificacy of ewes
Authors: Kirkwood R. N. , Thacker P. A. , Korchinski R. S. , Laarveld B. , Gonzalez A.
Published: March 2010

Ninety-six Suffolk ewes received daily injections of either long-acting insulin (1.0 IU kg−1) or saline for 3 consecutive days after introduction of rams. Basal serum LH concentrations were higher (P < 0.05) in insulin-treated ewes (P < 0.05) but concentrations of estradiol-17B and the magnitude of the preovulatory LH surge were unaffected. Interval to breeding, pregnancy rate and subsequent litter size were not influenced by treatment (66.6 vs. 63.3 h, 69 vs. 74% and 1.65 vs. 1.69 for insulin and saline-injected ewes, respectively). Key words: Insulin, sheep, fertility, prolificacy
Concentration of respirable dust and bioaerosols and identification of certain microbial types in a hog-growing facility
Authors: Butera M. , Smith J. H. , Morrison W. D. , Hacker R. R. , Kains F. A. , Ogilvie J. R.
Published: March 2010

In order to assess the effects of ventilation rate, temperature, relative humidity and source of air on bioaerosol levels and dust with particle size < 10 μm, a total of 120 pigs housed in 12 pens in two separate rooms were used. Pigs averaged 30 kg initially and the trials were discontinued when 20% of the pigs were marketed. A six-stage Andersen sampler and a light scattering particle counter were used to determine bioaerosols and respirable dust (0.1–10 μm), respectively. Total bioaerosols were assessed using Trypticase Soy Agar. Potato Dextrose Agar was used for fungal aeorsols and Baird-Parker Agar used for isolation of Staphylococcus aureus. Moulds amounted to less than 1% of total microorganisms. Gram positive bacteria made up 72% of the bacterial isolates. Respirable dust was not correlated with respirable bioaerosols. Ventilation rate (2, 5 or 8 changes h−1) did not affect bioaerosol level or respirable dust. Total bioaerosols were significantly reduced (P < 0.05) in higher temperatures only. Relative humidity did not influence total bioaerosols but in one series respirable bioaerosols were significantly (R = 0.53) (P < 0.05) correlated with RH. Total bioaerosols were not different in outside air or attic air. Key words: Dust, bioaerosols, pigs, ventilation
Carcass characteristics and meat quality of once-calved heifers
Authors: Vincent B. C. , Jones S. D. M. , Jeremiah L. E. , Newman J. A. , Price M. A.
Published: March 2010

Three groups of once-calved (OCH) heifers were slaughtered following the weaning of their calves at 3 (OCH3, n = 32), 5 (OCH5, n = 33) and 7 (OCH7, n = 31) months postcalving. A fourth group of heifers was fed a silage/grain diet and slaughtered at 15 mo of age (C, n = 32). Alternate sides of each carcass were electrically stimulated (ES) at 475 volts for 1 min (20 pulses m−1, 60 Hz) at 45 min post-stunning. All left sides were dissected into fat, lean and bone and meat quality parameters recorded. Rib eye steaks were evaluated for palatability by a trained panel and for consumer acceptability after an aging period of 6 d. All OCH groups produced heavier carcasses with a higher level of marbling than the C group after adjustment of the data to a constant proportion of carcass fatness, but the proportional yields of lean and bone tissue were similar for all heifer groups. OCH groups produced meat that was darker with a lower drip loss and higher 45 min and 6 d pH than the C group. Consumer acceptability of rib eye steaks was similar for all heifer groups, but the OCH7 (oldest) group had a higher amount of connective tissue when evaluated by a trained panel than other heifer groups. Taste panel evaluations showed that ES increased meat tenderness and overall palatability and reduced the amount of connective tissue when compared to meat from unstimulated carcasses. ES also increased the consumer acceptability of tenderness by 14.3%, flavor by 5.6%, juiciness by 5.2% and overall palatability by 6.7% over meat from unstimulated carcasses. It was concluded that once-calved heifers could produce heavier carcasses of similar composition and meat with similar eating quality to conventionally managed nonpregnant feedlot heifers. Electrical stimulation improved the consumer acceptability of meat primarily through an improvement in meat tenderness. Key words: Beef, carcass, electrical stimulation, meat quality, once-calved heifers
LH secretion in ovariectomized ewes: effects of morphine and ovarian steroid interactions with naloxone during the breeding season and anestrum
Authors: Currie W. D. , Cook S. J. , Rawlings N. C.
Published: March 2010

Morphine (MOR) infusion (i.v.) was used to mimic effects of endogenous opioid peptides (EOPs) on LH secretion in ovariectomized (OVX) ewes during the breeding season and anestrum. MOR decreased luteinizing hormone (LH) pulse frequency and/or amplitude at higher doses (0.5 and 1.0 mg kg−1 h−1), and increased basal serum LH concentrations at a lower dose (0.01 mg kg−1 h−1). Simultaneous MOR and naloxone (NAL) infusion (0.5 mg kg−1 h−1, each) did not affect LH secretion, suggesting that effects of MOR were EOP receptor-specific. EOP involvement in ovarian steroid feedback was examined by NAL infusion and ovarian steroid replacement in OVX ewes. NAL infusion increased LH pulse frequency in OVX ewes during the breeding season, suggesting ovarian steroid-independent, but EOP-dependent suppression of LH secretion. NAL did not alleviate seasonal suppression of LH pulse frequency during the anestrum, suggesting ovarian steroid-independent, EOP-independent suppression of LH secretion. NAL eliminated progesterone (P4) suppression of LH pulse frequency during the breeding season, suggesting that a major portion of P4 feedback on tonic LH secretion is EOP-dependent. P4 replacement in the anestrum did not suppress LH pulse frequency. NAL infusion, following P4 replacement in the anestrum, increased LH pulse frequency to levels observed in untreated OVX ewes during the breeding season. It was concluded that EOP-dependent P4 feedback experimentally over-rode EOP-independent suppression of LH pulse frequency during the anestrum. EOP activity was not required for estradiol (E2) to suppress LH secretion from the pituitary during the breeding season. Key words: LH, morphine, naloxone, progesterone, estradiol
Effects of lasalocid and cationomycin on the digestion of plant cell walls in sheep
Authors: Bogaert Catherine , Gomez L. , Jouany J. P.
Published: March 2010

The effect of lasalocid and cationomycin on plant cell wall digestion was tested in a Latin square design experiment over three periods on six adult sheep fed three diets: a control diet (T) without antibiotics, a diet (L) with 33 mg kg−1 of lasalocid, and a diet (C) with 33 mg kg−1 of cationomycin. The dry matter and plant cell wall digestibilities were not affected by the addition of antibiotics. The digestive flow measurements at the duodenum showed that the antibiotic had no effect on the apparent digestion of dry matter, organic matter and plant cell walls along the digestive tract. This was confirmed by the in sacco feed and pure cellulose rumen degradation measurements. Lasalocid, however, decreased the true digestion of feed dry matter in the rumen, as shown by the duodenal flow measurements after being corrected for microbial dry matter. Compared with the control diet, diets (L) and (C) increased the propionate percentage in the rumen VFA mixture (T = 14.9, L = 19.4, C = 18.9) and decreased acetate (T = 66.1, L = 63.8, C = 65.7) and butyrate (T = 14.1, L = 12.7, C = 11.7) percentages. The addition of antibiotics decreased the rumen ammonia nitrogen concentration by 14%. The CO2 to CH4 ratio in the gas mixture was, however, not statistically modified, and no ionophore effect was observed on the protozoa mean population. Key words: Lasalocid, cationomycin, digestion, cell wall carbohydrates, sheep, rumen
The influence of lasalocid and cationomycin on nitrogen digestion in sheep: Comparison of methods for estimating microbial nitrogen
Authors: Gomez L. , Jouany J. P. , Lassalas B. , Bogaert C.
Published: March 2010

An in vivo study was carried out to evaluate the effect of a new ionophore (cationomycin) on nitrogen digestion compared with lasalocid. Three diets based on forage were given (a control diet, a "cationomycin" diet, a "lasalocid" diet) to six sheep fitted with rumen duodenal and ileal cannulae over three different periods in a Latin square design experiment. The supply of lasalocid or cationomycin (33 mg kg−1) decreased (P < 0.05) the breakdown of dietary proteins in the rumen and lowered the microbial protein synthesis whatever the microbial marker used (diaminopimelic acid or purine bases). The duodenal and ileal flows of organic matter (OM), ammonia nitrogen (NH3-N), nonammonia nitrogen, and amino acids (AA) were not affected by the ionophore addition. We could not use the AA profile method to estimate the microbial contribution to the duodenal flow of nonammonia nitrogen because of the strong similarities in AA composition of the feed and the rumen microbial sample. The efficiency of microbial synthesis was significantly (P < 0.05) decreased by cationomycin, and tended to decrease with lasalocid. Only lasalocid increased the digestibility of dietary nitrogen in all the digestive tract. Key words: Ionophore, lasalocid, cationomycin, digestion, nitrogen, sheep, rumen
The effect of enzyme supplementation on the nutritive value of rye-based diets for swine
Authors: Thacker P. A. , Campbell G. L. , GrootWassink J.
Published: March 2010

A total of 138 crossbred pigs were fed either a barley-based control diet or a rye-based diet supplemented or unsupplemented with a crude enzyme preparation with pentosanase activity. Digestibility coefficients were generally higher (P < 0.05) for pigs fed rye-based diets in comparison with barley while enzyme supplementation had no effect on nutrient digestibility. When fed in a meal form, there was a significant reduction (P < 0.05) in the growth rate of pigs fed rye-based diets compared with barley (exp. 1). However, no significant differences were observed when pelleted diets were fed (exp. 2). The results of both experiments indicate that rye-based diets are not consumed as readily as barley-based diets although pigs fed rye-based diets had improved feed efficiencies. Supplementation with pentosanase did not significantly improve pig performance although in both experiments, there was a trend towards an improvement in growth rate. In exp. 1, there were no significant differences (P > 0.05) in slaughter weight, carcass weight, dressing percentage, estimated lean yield or carcass value index as a result of differences in the cereal base of the diet or enzyme supplementation. In exp. 2, the carcass weight and dressing percentage of pigs fed the rye-based diets were lower than those of the control (P < 0.05). In conclusion, it would appear that soluble pentosans do not pose as large a problem for swine as they do for poultry. Key words: Swine, rye, pentosans, pentosanase, digestibility
Nutritional evaluation of very low glucosinolate canola meal
Authors: Bell J. M. , Keith M. O. , Hutcheson D. S.
Published: March 2010

Two very low glucosinolate (VLG) canola meals from crop years 1987 and 1988 (CM; 1.66 and 0.53 μmol g−1) and two Tobin CM (B. campestris) (10.71 and 15.62 μmol g−1) were evaluated in experiments with pigs. In exp. 1, 1987 Tobin CM, VLG-CM and soybean meal (SBM) were compared in individually fed meal and pelleted diets. Daily gains from 23 to 57 kg were similar for the CMs (VLG-CM 662 g, Tobin CM 645 g) but lower than those obtained with SBM (730 g; P < 0.01). Daily feed intakes of pigs fed CM were lower than for those fed SBM (P < 0.05). Plasma thyroxine (T4) levels were similar for SBM and VLG-CM and were above those from pigs fed Tobin (P < 0.05) CM. Triiodothyronine (T3) levels were lower for VLG-CM than for SBM (P < 0.05) and the T3 value for Tobin CM was intermediate. Pelleting enhanced T3 (0.70 vs 0.94 ng mL−1) and T4 (50 vs. 60 ng mL−1) levels with all protein supplements (P < 0.01). In exp. 2, similar diets were fed ad libitum. Daily gains for SBM were greater than for Tobin CM (803 vs. 744, P < 0.05) and gains for pigs fed VLG-CM was 774 g. Daily feed intakes were similar (2.01, 1.99 and 1.92 kg). In exp. 3 energy digestibility of 1987 VLG-CM was greater (P < 0.01) than for Tobin CM (75.0 vs 67.4% for 30-kg pigs). Apparent digestibility coefficients of crude protein (CP) were 71.9, 71.2 and 71.6 in 16% CP diets. In exp. 4 Tobin and VLG-CMs from 1987 and 1988 crops were compared with SBM and commercial CM using 96 pigs (48M, 48F). Daily gains and feed intakes were similar for the CMs but T3 and T4 values were below those of SBM (P < 0.05). Key words: Canola meal, very low glucosinolate, digestibility, feeding value, pigs
Nutritional characteristics of Angus cows differing in lifetime calf production
Authors: Hohenboken William D. , Bass II Roger T. , Fontenot J. P. , McClure William H.
Published: March 2010

Cows with better versus poorer lifetime calf production did not differ significantly in intake or passage rate of digesta under ad libitum concentrate or roughage feeding. On the concentrate diet, better cows tended towards greater fat accretion than poorer cows. On roughage they maintained, while poorer cows lost fat thickness. Key words: Cows, intake, passage rate, fat thickness
Estimates of heritabilities of Canadian Holstein conformation traits by threshold model
Authors: Jamrozik J. , Schaeffer L. R. , Burnside E. B. , Sullivan B. P.
Published: March 2010

Sire variances for 30 conformation traits on Canadian Holsteins were estimated on the underlying continuous scale using a single trait threshold linear model. Data were linearized first classifications on 66 617 cows by 3305 sires, classified since February 1988. The model included a random sire effect and fixed effects of herd-round of classification-classifier, age at classification and stage of lactation at classification. Sires were assumed unrelated in this study. Variance components for sires were estimated by REML EM algorithm. Estimates of heritabilities were generally larger than those currently used in genetic evaluation for type traits in Canadian Holstein population. The new heritabilities are recommended for use in a traditional linear animal model procedure. Key words: Variance components, threshold model, type traits
Variability in the rumen degradability and postruminal digestion of the dry matter, nitrogen and amino acids of canola meal
Authors: Kendall E. M. , Ingalls J. R. , Boila R. J.
Published: March 2010

The rumen degradability and postruminal digestion of rumen escape dry matter (DM), nitrogen (N) and metabolically essential amino acids (EAA) for canola meal (CM) from five different processing plants (samples 1–5) and one sample of soybean meal (SBM) were compared. Rumen degradability was estimated by incubating sample-filled small nylon bags in situ in the rumen of steers for 0, 4, 8, 12, 16 and 30 h. Postruminal digestion was estimated using a sequence of ruminal in situ incubations for 0, 4, 8, 12 and 16 h, in vitro incubation in an acid-pepsin solution and a mobile nylon bag technique distal to the abomasum. The rumen escape of nutrients for CM1 was consistently lower compared to other CM samples, while CM4 resulted in the highest escape of nutrients at 30 h. An estimate of maximum degradability of EAA measured at 30 h differed among CM samples, with the rumen escape of EAA being CM4 > CM2 = CM5 ≥ CM1 = CM3 > SBM. The DM, N and EAA content of mobile bag residues was relatively uniform among CM samples, particularly after 12 and 16 h of ruminal fermentation, but was higher for CM than for SBM, probably due to a low digestibility of CM hulls. The rumen degradability of CM from different processing plants differed and as a consequence the postruminal digestion of nutrients in CM differed. Key words: Canola meal, rumen degradability, postruminal digestion, dry matter, nitrogen, amino acids
Effect of dietary ergot on the mean transit time of digesta in the small intestine of sheep
Authors: Rotter R. G. , Phillips G. D.
Published: March 2010

Ergot (Claviceps purpurea) causes serious deleterious effects in animals which ingest it, and it may also affect the rate of passage of digesta through the intestine. In a Latin square design experiment with repeated measurements, the mean transit times (MTT) of digesta in the small intestine were determined in four intact rams fed ergot (0.0, 0.05, 0.10 and 0.15% of the diet) with their daily feed allotments. Although there was a very slight indication of an effect as the ergot treatment concentration increased, the values were not significantly different (P > 0.05). Despite possible differences in the effects of individual constituent ergot alkaloids, there was no affect on the MTT in the small intestine of sheep. Key words: Ergot, rate of passage, sheep, mean transit time
Duodenal flow of nitrogen following protozoal inoculation of fauna-free sheep fed a diet supplemented with casein or soybean meal
Authors: Ivan M. , Hidiroglou M. , Petit H. V.
Published: March 2010

Fauna-free sheep, equipped with a rumen cannula and a duodenal re-entrant cannula, were fed a corn silage diet supplemented with casein (CA diet) or soybean meal (SBM diet). Eighteen days later the sheep were inoculated via the rumen cannula with a mixed population of ciliate protozoa. Rumen fluid and duodenal digesta were sampled for 4 d before the inoculation and for 13 d following the inoculation. A stable protozoal population was established within 8 d. Protozoa increased (P < 0.05) the digestion of organic matter in the stomach of sheep fed both the CA and the SBM diet, but the effects of supplemental protein and protein × protozoa interaction were not significant (P > 0.05). The stomach digestion of acid detergent fibre was not affected (P > 0.05) by protozoa or by the source of supplementary protein, but the protein × protozoa interaction was significant (P < 0.05). The disappearance of nitrogen from the stomach was lower (P < 0.01) for the SBM diet than for the CA diet and was increased (P < 0.05) for both diets in the presence of protozoa, but the effect of protein × protozoa interaction was not significant (P > 0.05). The ruminal presence of protozoa decreased the flow from the stomach of individual amino acids (from P < 0.05 to P < 0.001) and of nonammonia nitrogen (P < 0.05). However, the decreases were greater (from P < 0.05 to P < 0.001) for the CA diet than for the SBM diet, but the effects of protein × protozoa interaction were not significant (P > 0.05). The ruminal presence of protozoa increased (P < 0.05) the flow from the stomach of ammonia-N for SBM diet but not for CA diet. The effects of protein and of protein × protozoa interaction were not significant (P > 0.05). It was concluded that although ruminal protozoa do not metabolize casein, their effect of decreasing amino acid flow from the stomach can be greater for diets containing casein (soluble protein) as protein supplement than for those containing soybean meal (insoluble protein). Key words: Duodenal flow, nitrogen, protozoa, casein, soybean meal, sheep
Response of growing cattle to supplementation with organically bound or inorganic sources of selenium or yeast cultures
Authors: Nicholson J. W. G. , McQueen R. E. , Bush R. S.
Published: March 2010

Bioavailability of organically bound and inorganic Se sources differ, the organic form being absorbed more efficiently. Dairy and beef calves (250 kg initial weight) were given a low Se diet alone or supplemented with sodium selenite (1 mg Se d−1; inorganic Se), a Se-enriched yeast (1.5 g yeast d−1 providing 1 mg of Se; organic Se), a live yeast culture (1.5 g d−1) or autoclaved yeast culture (1.5 g d−1). The latter treatments were included to determine the response to yeast per se. There were no treatment effects on rate of weight gain or efficiency of feed conversion by the calves. The Se souces had no effect on digestibility of the diet by sheep. The inorganic Se supplement increased the level of whole blood Se and glutathione peroxidase (GSH-Px) activity at a linear rate with time up to 3 mo from the start of supplementation. The effect of organic Se was sustained for 4 mo and both indices of Se status in blood were higher (P < 0.01) for calves fed the organic Se than for those fed inorganic Se after 4 mo (124 vs. 96 units of GSH-Px activity g−1 haemoglobin and 141 vs. 102 μg Se L−1 of whole blood). The values near the beginning of the trial were higher (P < 0.01) for Holstein calves than for beef calves but both groups showed the same response to source of Se. Subsequently, levels declined for Holstein and increased for beef calves given diets without supplemental Se. The results showed that Se supplementation for 4 mo had no effect on animal performance; that more than 4 mo are required to fully deplete or replete blood Se and GSH-Px; and, that supplemental organic Se gives higher (P < 0.01) blood Se and GSH-Px activity than does inorganic Se. Key words: Organic selenium, calves, glutathione peroxidase
Effect of nitrogen fertilizer on beef production and forage quality of Russian wildrye
Authors: Holt N. W. , Zentner R. P. , Lawrence T. , Kilcher M. R. , Peters H.
Published: March 2010

A grazing study was conducted for 12 yr on a Brown loam in a semi-arid climate at Swift Current, Saskatchewan to determine the effect of nitrogen (N) fertilizer on beef production, forage quality, and economic returns of Russian wildrye (Psathyrostachys juncea (Fisch) Nevski) (RWR). Treatments were: annual broadcast of N fertilizer such that available soil N (0–60 cm depth) plus applied N totalled 55 kg ha−1; an application in which available plus applied N totalled 110 kg ha−1; a one-time application of 390 kg N ha−1 (April 1977); and a control treatment with no fertilizer. Treatments were compared by regression analysis using soil available plus fertilizer N and age of stand as the independent variables. Pastures were grazed each year with yearling steers from early May until 5 cm grass height remained or when steers did not gain weight in a 2-wk period (resulting in an average grazing period of 120 d). Total grazing days averaged 166, 179, 165 and 132 days ha−1, respectively, for the four treatments. For the 55 N treatment, in which 32 kg N ha−1 was applied annually, an average of 1 kg of beef gain was obtained for each kilogram of N applied. Daily gain of steers averaged 0.84 kg d−1 for all years and treatments. Stocking rate (grazing days/ha) was positively correlated to spring soil moisture plus grazing season precipitation (r = 0.67) and negatively related to pan evaporation (r = 0.87). Fertilizer treatments marginally increased forage N and OMD early in the season. Forage N, phosphorus, and organic matter digestibility (OMD) declined in a linear relationship with time from 1 May. The rate of decline was not affected by the treatments. On the basis of liveweight gain, all fertilizer treatments were profitable. Profitability varied with the ratio of the cost of fertilizer N to steer price; annual fertilizer applications were more profitable than the one-time application. Key words: Psathyrostachys juncea, yearling steer performance, forage digestibility, forage quality
Benefits of using a photo-electric alert system for swine farrowing operations
Authors: Bate L. A. , Crossley J. G. , Hurnik D.
Published: March 2010

A system has been designed to alert swine producers when the farrowing process has begun. The results indicate a potential for the alert system to reduce stillbirths. No differences in body weight of piglets, nor differences in bacterial growth in the sows as a result of using the alert system tampon, were observed. Key words: Farrowing, alert system, piglet, mortality, stillborn
Nycterohemeral variations of concentration of serum folates in dairy cows
Authors: Tremblay G. F. , Girard C. L. , Matte J. J. , Bernier-Cardou M.
Published: March 2010

Nycterohemeral variations of serum folates were observed under two different management practices in 11 dairy cows. Serum folates were lower (P = 0.0018) during the nonlactating period (9.68 ± 0.65 ng mL−1) than during the lactating period (13.29 ± 0.65 ng mL−1). During the nonlactating period, nycterohemeral variations of serum folates could not be distinguished from experimental error. During the lactating period, expected serum folates did not vary by more than 1 ng mL−1 around their mean. Key words: Serum folates, nycterohemeral variations, lactating cows, nonlactating cows