bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of a long-acting gonadotrophin-releasing hormone agonist (Leuprolide) on ovarian follicular development in prepubertal heifer calves
Authors: Evans A. C. O. , Rawlings N. C.
Published: March 2010

We studied the effects of reducing gonadotrophin secretion on ovarian follicular development in young prepubertal heifer calves. Calves received a GnRH agonist (n = 5, 15 mg of Leuprolide acetate, i.m.) or carrier (n = 5) at 8 and 12 w of age. Starting at 8 and 34 w of age, ovarian follicles were monitored daily for 17 d, and at 10, 15, 25 and 35 w of age, blood samples were collected every 15 min for 12 h for measurement of serum concentration of LH and FSH. GnRH agonist treatment did not affect the age and body weight at puberty (P > 0.05). Agonist treatment suppressed follicle numbers and in two heifers follicle emergence (growth above 4–5 mm) was blocked immediately. In three agonist-treated heifers, follicle emergence was blocked after one extended wave of follicular growth. At 34 w of age the pattern of ovarian follicular growth did not differ between groups but oestradiol secretion was lower in agonist-treated heifers. During agonist treatment basal and mean concentrations of FSH, and LH and FSH pulse amplitude were decreased but basal LH concentrations increased (P < 0.05). At 25 and 35 w of age some rebound in gonadotrophin secretion was seen.We concluded that disrupting gonadotrophin secretion in young prepubertal heifer calves by GnRH agonist treatment, suppressed ovarian follicular growth but that a rebound in gonadotrophin secretion prevented long term-effects on sexual development. Key words: Follicle stimulating hormone, gonadotrophin-releasing hormone, heifer calves, luteinising hormone ovarian follicles
Influence of dietary fat source on oxidative stability and fatty acid composition of milk from cows receiving a low or high level of dietary vitamin E
Authors: Charmley E. , Nicholson J. W. G.
Published: March 2010

Fifteen primiparous Holsteins were used in a latin square design with three periods and three treatments to assess the effect of fat source on milk flavour, yield and composition, and composition of milk fat. A basal diet was supplemented with one of three concentrates offered twice daily: soybean meal (no supplemental fat); cracked, micronized soybeans (containing 20 g kg−1 oil); and soybean meal plus CSFA which supplies an amount of fat similar to that of the soybeans. Periods lasted 6 wk, and each cow received 6000 IU dL α-tocopheryl acetate d−1 for the last 2 wk of each period. Measurements of milk yield, composition and flavour were made at the end of weeks 4 and 6 of each period. Feeding CSFA reduced DM intake (P = 0.064), but fat supplemented diets tended to supply more NE1 than the unsupplemented diet (P = 0.085). Yields of milk (P < 0.001), fat (P < 0.001) and energy (P = 0.003) were increased by fat supplementation. Protein yield was reduced (P = 0.003) when CSFA were fed. Soybeans reduced fat concentration in milk, but only before supplemental vitamin E was given. Soybeans increased α-tocopherol output in milk (P < 0.05). Milk from cows fed soybeans was most susceptible to oxidation (P < 0.01). Intensity of oxidized flavour was similar before and during vitamin E supplementation. Fat supplementation reduced the proportion of short- and medium-chain fatty acids (P < 0.001) and increased the proportion of C18 fatty acids in milk (P < 0.001). Soybeans increased the proportion of polyunsaturated fatty acids in milk but CSFA did not. Soybeans can escape biohydrogenation in the rumen and render milk susceptible to oxidation by increasing the proportion of polyunsaturated fatty acids. At the levels fed, vitamin E did not prevent oxidation due to its low transfer to milk. Key words: Oxidized milk, fatty acids, soybeans, tocopherol, dairy cow
Apparent digestibility of protein and amino acids at the distal ileum and of protein and energy over the whole tract in several extruded soybean cultivars for pigs
Authors: Marty Bruno J. , Chavez Eduardo R.
Published: March 2010

Three soybean cultivars (Maple Arrow, Maple Belle, and Maple Glen) commonly grown in the province of Quebec were heat processed by a single-screw dry extrusion process. These soybean products were mixed into cornstarch-based diets that were formulated to provide 16% crude protein. Diets were fed according to a repeated 3 × 3 Latin square design to six gilts fitted with simple T-shaped ileal cannulas. Experimental observations, including apparent digestibilities of amino acids and crude proteins at the distal ileum and of crude protein and energy over the whole tract were not significantly affected by soybean cultivar (P > 0.05). Key words: Full-fat soybean, cultivar, extrusion, digestibility, pigs
Association of class I bovine lymphocyte antigens with production traits in the Ayrshire breed
Authors: Batra T. R. , Macdonald P. A. , Stear M. J.
Published: March 2010

Ninety progeny tested Canadian Ayrshire bulls were serologically typed for the BoLA-A locus to determine the association of these alleles with production traits. After exclusion of bulls carrying alleles that occurred at frequencies lower than 2% or whose production proofs were not available, records from 78 bulls remained for analysis. A gene substitution model, which included the effects of BoLA alleles and the breeding value of the sire of the bull as covariate, was used to evaluate the additive effects of BoLA alleles of bulls (ETAs) on the production traits of their daughters. Allele W17 was significantly associated with ETA for milk, fat and protein yields. Allele CA96 was associated with significant increases in ETA for fat yield. There was no significant association of BoLA alleles with either ETA for fat or protein percentage. Key words: BoLA, production traits, Ayrshire
Current and emerging approaches to assuring the hygienic condition of red meats
Authors: Gill C. O.
Published: March 2010

Current meat inspection activities exclude overtly diseased animals and carcasses from human consumption, and prevent grossly unhygienic meat production practices. However, they have signally failed to reduce the incidence of enteric pathogens on meat although the transmission of such organisms from asymptomatic animals is recognized as the major health risk associated with meat. The general hygienic condition of meat will be improved only if effective Hazard Analysis: Critical Control Point (HACCP) systems can be developed for meat production, preparation and distribution processes. The development of effective HACCP systems is impeded by the uncertain commitment of managements to product improvement, the lack of defined procedures for the objective identification of hazardous practices, and the persistence of the subjective assessment of the hygienic condition of product. The development of objective procedures for hazard analysis could precipitate the resolution of the other impediments to HACCP implementation. Key words: Meat hygiene, meat inspection, hazard analysis, process control, HACCP
Alternatives for genetic evaluation with uncertain parentage
Authors: Sullivan P. G.
Published: March 2010

Alternative methods of genetic evaluation which consider uncertain paternity were compared theoretically and through Monte Carlo simulation. Records were simulated for 300 base generation animals and 10 subsequent generations of 100 animals each. Probabilities of paternal uncertainty were either 20 or 50%, heritability was 0.05, 0.25 or 0.50, mating was random with a female-to-male ratio of 5, and selection of breeding animals was either random or by truncation on phenotype. Simulations were replicated 10 times. Differences in expected selection response, for the genetic evaluation methods studied, were largest when heritability was low and degree of paternal uncertainty high. Expected response to selection was maximized in all cases by using uncertain paternity methods instead of genetic grouping or other methods. Advantages over genetic grouping ranged from 0 to 16%. The exclusion of performance records of animals with paternal uncertainty reduced expected selection response by as much as 37%, in addition to the reduction in expected response caused by excluding from selection animals with uncertain parents. All methods that accounted for true or probable paternity, either directly or through genetic groups, yielded unbiased estimates of genetic trends. Key words: Uncertain parentage, numerator relationship matrix, genetic grouping, genetic evaluation, genetic progress, Monte Carlo Simulation
Control of the bioavailability of iron in heavy veal production by different feeding management systems: Use of Ca–EDTA as an iron chelating agent
Authors: Pommier S. A. , Lapierre H. , Passillé A. M. de , Gariépy C.
Published: March 2010

Seventy male dairy black and white veal calves were allotted to five treatment groups: MILK, in which animals received exclusively milk replacer; MIX, in which animals received concentrates ad lib and milk replacer during the whole period, more specifically, 750 g of milk powder d−1 starting at week 4; GRAIN, in which animals received milk replacer during the first 4 wk and concentrates during the whole period; MIX+EDTA and GRAIN+EDTA, in which animals received the same diet as their respective controls plus 15 mg of EDTA mg−1 of Fe in the concentrates of the diet starting at week 4 of the experiment. MILK–fed calves had better average daily gains (ADG) than MIX–EDTA–fed or GRAIN+EDTA–fed calves (P < 0.001). However, GRAIN+EDTA–fed calves had lower ADG than GRAIN calves (P < 0.01). The EDTA treatments were without effect (P > 0.10) on feed efficiency and EDTA did not affect N digestibility (P > 0.10) or Fe retention (P > 0.10). Treatments with EDTA lightened the color of the meat (P < 0.01), reduced myoglobin and reduced muscle Fe (P < 0.01). Diet reduced carcass fatness in the following decreasing order: MILK, MIX, GRAIN. Treatments with EDTA had no effect on carcass composition. Key words: Veal, milk-replacer, grain, meat color, chelator
Effect of selection for feedlot gain, breed and age on growth hormone and growth hormone kinetics in bull calves
Authors: Mears G. J. , Kozub G. C.
Published: March 2010

Average daily gain, basal GH, and plasma GH kinetics following a bolus injection of GH were determined at birth and at 75, 150, 250, 350 and 450 kg BW in 17 Hereford and 19 Angus bull calves. Calves were offspring of two lines within each breed selected for six generations for rapid 168-d feedlot gain on either a roughage or a concentrate diet. These four lines were from a long-term selection study that were being evaluated to determine the effects of selection diet on factors that regulated their growth rate. Hereford calves weighed more (P < 0.01) at birth. Both breeds had similar (P > 0.05) ADG between birth and 450 kg BW. Overall ADG was positively correlated with birth weight within both breeds (P < 0.01). Selection diet had no effect (P > 0.05) on ADG, basal GH, VSS, T1/2, MCR and SR. Compared with Hereford calves, Angus calves had higher MCR (P < 0.05) and SR (P < 0.1) for both diets, and lower basal GH (P < 0.05) for the concentrate diet. Basal GH (P < 0.01), VSS (P < 0.01), T1/2 (P < 0.05), MCR (P < 0.01), and SR (P < 0.01) generally decreased as calf weights (and age) increased. Basal GH and kinetic parameters were correlated with ADG in only a few instances mostly between birth and 250 kg BW. Several GH kinetic parameters obtained between 150 and 450 kg BW were correlated with calf birth weight. We conclude that ADG and GH kinetics are more closely related to calf birth weight than to diet fed during selection for rapid feedlot gain. Key words: selection for gain, Hereford and Angus cattle, bull calves, growth hormone, GH, kinetics
Effects of bovine follicular fluid and luteinizing-hormone-releasing hormone antagonist on the dominant follicle maintained by a norgestomet ear implant in heifers
Authors: Manikkam M. , Rajamahendran R. , Rawlings N. C.
Published: March 2010

The effects of BFF and LHRHa on the dominant follicle, maintained by 9-d synthetic progestin (norgestomet) ear implants inserted at proestrus, were studied in cattle. From day 4 of implant insertion, heifers (n = 18) were injected twice daily with saline (control, n = 6) or charcoal-extracted bovine follicular fluid, 10 mL i.v. for 4 d (BFF, n = 6) or LHRHa, 0.8 mg i.v. for 3 d (LHRHa, n = 6). Follicular changes were monitored daily by ultrasonography. Plasma estradiol-17β, serum LH and FSH were measured by radioimmunoassays. The dominant follicle was maintained during the treatment period, and it ovulated after implant removal in control heifers. In BFF group, the dominant follicle either ovulated after implant removal (two of six heifers) or gradually regressed until day 10 in the post-implant period (other four of six heifers). In the LHRHa group, the dominant follicle regressed during or after the implant period in 5 of 6 heifers. The dominant follicle ovulated in 1 of 6 heifers. Growth rate of the dominant follicle, until it reached its maximum diameter, was lower in BFF group than the control group (0.4 ± 0.1 vs 0.7 ± 0.1 mm d−1; P < 0.01). Both BFF and LHRHa groups showed high regression rates in those follicles that did regress (2.2 ± 0.1 (n = 4) and 1.9 ± 0.8 mm d−1 (n = 5) respectively; P < 0.01), compared with no regression in the control group. The BFF injections failed to suppress serum FSH levels consistently in all the heifers treated. LHRHa-treated heifers showed a significant decline (P < 0.01) in the mean serum LH concentration. In conclusion, deprivation of LH causes atresia of the dominant follicle. Key words: Follicular fluid, LHRH antagonist, follicular dynamics, gonadotropins, estradiol-17β, ultrasound, regression
Effects of β-agonist, L-644,969, on adipose depots in growing female rats
Authors: Zhang J. , Grieve D. G.
Published: March 2010

Growing female Sprague Dawley rats (n = 33) were used to determine the effects of β-agonist, L-644,969, on adipose depots, mammary growth and plasma ST and IGF-I levels. Fat-cell diameter in SF and PF, and mammary DNA content were studied. Rats were allocated to three groups to receive 0,4 or 8 mg kg−1 L-644,969 in powdered diet for 35 d. Compared with control, total mammary gland weight, as a proportion of final body weight, was reduced 14.6 (P < 0.05) and 35.6% (P < 0.01), PF was reduced 30 and 49.6% (both P < 0.01) by 4 and 8 mg kg−1, respectively. The SF was reduced 22.3% (P < 0.05) by β-agonist at 8 mg kg−1 only. In all fat depots, the reductions increased with increasing dose of β-agonist. Carcass fat percentage was reduced by 28.5 and 41.7% (both P < 0.01) in rats fed β-agonist at 4 and 8 ppm, respectively. Fat-cell diameter in both SF and PF was reduced (P < 0.05) (except at 4 ppm level in SF), and mammary DNA content was increased (P < 0.01) in both treatment groups. There was a trend to increased ST concentration but to lower IGF-I concentration as β-agonist levels in diet increased (P > 0.1). The results indicate that β-agonist is effective in reducing body fat deposition and fat-cell size and stimulating mammary gland growth, which may play a role in the control of mammogenesis in growing rats. Key words: Rats, β-agonist, mammary gland, adipose tissue
A comparison of choice and phase feeding for growing–finishing pigs
Authors: Nam D. S. , Aherne F. X.
Published: March 2010

A growing-finishing trial using 72 crossbred gilts (19.7 kg initially) was conducted to evaluate the effectiveness of choice feeding in the production of pigs. Six pens of three gilts were assigned to each of the following feeding systems: (1) conventional three-phase feeding (18–16–14% crude protein; P3), (2) one-phase feeding (16%; P1), (3) three-phase choice feeding (24–14, 22–12, 20–10%; C3) of two diets differing in protein level, and (4) one-phase choice feeding (24–10% throughout; CI). The three growth periods were 20–50, 50–70 and 70–105 kg live weight. All diets were based on barley and soybean meal and contained the same energy level (13.7 MJ DE kg−1). Choice feeding systems (C1 and C3) during the grower period (20–50 kg) increased (P < 0.05) feed intake (1.52 vs. 1.33 kg d−1) and weight gain (801 vs. 731 g d−1) compared with those of phase feeding (P1 and P3). In the 50–105 kg growth phase, feeding systems had no effect on pig growth performance. Feed intake over the entire period (20–105 kg) was higher (P < 0.05) with choice feeding (2.55 kg d−1) than with phase feeding (2.27). Dietary protein intake increased (P < 0.05) by 18% in choice-fed pigs, and more dietary protein was required (P < 0.05) for weight gain from choice feeding than from phase feeding. There were no significant differences in the protein content of the diets selected by C1 and C3 pigs for any period or for the overall experiment. There were no significant effects of feeding system on carcass traits, except that carcass dressing percentage was highest (P < 0.05) for C3 pigs. These results suggest that choice-fed pigs consumed more dietary protein and required more protein for weight gain than pigs in a phase feeding system. Also, growing–finishing pigs do not have the ability to select a protein intake to meet their requirement for protein when they are provided a choice of diets differing in protein content. There was no advantage to using a three-phase choice feeding system rather than a singe-phase choice system. Key words: Choice feeding, protein selection, performance, carcass characteristics, pigs
The effect of oligosaccharides and lactitol on the ileal digestibilities of amino acids, monosaccharides and bacterial populations and metabolites in the small intestine of weanling pigs
Authors: Gabert V. M. , Sauer W. C. , Mosenthin R. , Schmitz M. , Ahrens F.
Published: March 2010

An experiment was carried out to examine the effects of supplementing diets for weanling pigs with oligosaccharides and LAC on nutrient digestion and bacterial populations and metabolites in the small intestine. Twelve barrows, weaned at 28 d, were fitted with a simple T-cannula at the distal ileum. The BW of the pigs at weaning and at the conclusion of the experiment were 9.1 and 13.8 kg, respectively. The pigs were fed four diets based on barley, wheat and soybean meal according to a two-period change-over design. The diets were formulated to contain 18% CP. Transgalactosylated oligosaccharides (0.2%), GUO (0.2%) and LAC (1%, 4-O-β-D-galactopyranosyl-D-sorbitol) were included at the expense of corn starch. Supplementation with oligosaccharides or LAC had little effect on the apparent ileal digestibilities of AA and monosaccharides. Supplementation of diets with oligosaccharides or LAC did not affect (P > 0.05) the monosaccharide concentrations in ileal digesta except for galactose which was higher (P < 0.05) in digesta from pigs fed the diet supplemented with LAC. The daily ileal output of monosaccharides, pH, ammonia and VFA concentrations, bacterial populations in ileal digesta and incidence of diarrhea were not affected (P > 0.05). Therefore, the supplementation of diets for weanling pigs (9.1–13.8 kg) with oligosaccharides or LAC at these levels does not affect nutrient digestibilities and bacterial populations in the small intestine. Key words: Pigs, oligosaccharides, lactitol, digestibility, bacteria
The effect of microbial phytase in diets for pigs on apparent ileal and faecal digestibility, pH and flow of digesta measurements in growing pigs fed a high-fibre diet
Authors: Bruce J. A. M. , Sundstøl F.
Published: March 2010

The effect of Aspergillus niger phytase on digestibility of some nutrients, pH and flow of digesta in post valvular T-caecum (PVTC) cannulated growing pigs fed an oat (80.6%) diet was studied. Four barrows weighing on average 40 kg were assigned to four diets in a 4 × 4 Latin square design. Diet 1 contained 1.11% monocalcium phosphate (MCP); diet 2 had neither MCP nor phytase; diet 3 included phytase at a concentration of 487 phytase units kg−1 feed; and diet 4 had 0.55% MCP and 320 phytase units kg−1 feed. Ileal digestibility of phosphorus (P) increased by 19.4 and 26.8% in diets containing microbial phytase compared with the control diets 1 and 2, respectively. Corresponding increases in faecal digestibility values were 18.3 and 23.6%. Ileal digestibility of calcium (Ca) was significantly higher in diet 3 but there was no effect of diet on the faecal digestibility of Ca. There was no effect of microbial phytase on the digestibility of magnesium (Mg), dry matter (DM) or crude protein (CP). Ileal digestibility of crude fibre (CF) was not affected by diet, but faecal CF digestibility was lower (P < 0.05) in diets containing microbial phytase. There was no effect of phytase on excretion of Ca, Mg and N and Mg and N retention. There was a time-related response of pH of ileal digesta, with hourly pH measurements ranging between 7.1 and 5.9, irrespective of diet. Flow of digesta peaked 3–6 h after the morning feed and 1–2 hours after the evening feed. Key words: Pigs, cannulation, phytase, digestibility, pH
A survey of production characteristics, ownership and extension needs of the Alberta dairy industry
Authors: Goonewardene L. A. , Spicer H. M. , McNeil A. O. , Slack W. L.
Published: March 2010

All dairy producers in the province of Alberta were mailed a questionnaire to determine current production and management practices. Eight hundred and two producers (55.7%) responded. The average herd size was 67 ± 39 cows and milking cow production was 21.9 ± 4.7 kg d−1. A large proportion of farmers owned their land and the farm mainly supported one or two families. The principal operators worked full time on the farm and few sought outside employment. About 28% of farmers owned personal computers but were slow to take advantage of this technology. Farmers received extension information primarily from veterinarians and other dairy producers, while the Alberta Dairy Producers newsletter was the primary medium of receiving information. Over 90% of the producers surveyed either planned to maintain present levels of production or expand. Milking cow production was influenced by operator experience and level of education. Those respondents who planned on maintaining or expanding their production had significantly (P < 0.05) larger herds. Key words: Survey, production, dairy, Alberta, management
Use of ultrasound in prediction of carcass characteristics in lambs
Authors: Stanford K. , Clark I. , Jones S. D. M.
Published: March 2010

Longissimus muscle area, maximum depth and maximum width and subcutaneous fat thickness were measured ultrasonically at the first lumbar vertebra on 1162 lambs. Lambs were rams, ewes and wethers, ranging in age from 3 to 15 mo, with liveweights ranging from 32.5 to 70.2 kg. Subjective conformation scores of the leg, loin and shoulder and body-wall thickness at the GR site (11 cm from the carcass midline between the 12th and 13th ribs) were measured on warm carcasses and were used to determine lean-meat yield. Saleable-meat yield and percentage of saleable-meat yield in each of the primal cuts were also determined by carcass dissection of 57 of the lambs. Stepwise regression equations predicting GR and lean-meat yield from ultrasound measurements, age, (age)2, liveweight and (liveweight)2 had an R2 of 0.49 and 0.47, respectively (P < 0.15). Stepwise regression predicting saleable-meat yield by carcass dissection from ultrasound measurements, age, (age)2, liveweight and (liveweight)2 had an R2 of 0.64, with subcutaneous fat as the only significant regressor (P < 0.001). Stepwise discriminant analysis used to predict leg, loin and shoulder conformation scores from ultrasound measures, liveweight, (liveweight)2, (age)2 and age had R2 values of 0.27, 0.18 and 0.24, respectively (P < 0.15). From these data, ultrasound measurements of subcutaneous fat and longissimus depth in combination with liveweight and age appear to be valuable predictors of saleable-meat yield as determined by carcass dissection, GR and lean-meat yield but appear to be less useful in prediction of subjective muscling scores, except in the case of small-frame lambs. Key words: Ultrasound, lamb, carcass, meat yield
Effects of dietary protein and β-agonist on growth and fat deposition in prepubertal lambs
Authors: Zhang J. , Grieve D. G. , Coomber B. L.
Published: March 2010

Weaned female lambs were used to study the effects of dietary protein (15 or 20%) and β-agonist (L-644,969: 0 mg kg−1 or 1 mg kg−1) on fat deposition between weaning and puberty. Lambs were fed pelleted concentrate plus 200 g hay d−1 to achieve a target weight gain of 260 g d−1. The trial continued for 102 d with dietary protein treatment starting on day 1 and β-agonist starting on day 20. Comparisons were made between the two levels in each of the two factors when there was no interaction. Carcass fat was reduced by 19.1% (P < 0.01) and carcass protein was increased by 15.8% (P < 0.01) in lambs fed the β-agonist. Carcass fat and protein were not affected by dietary protein. There was a nonsignificant trend to lower kidney-pelvic fat and subcutaneous fat thickness with the β-agonist (P > 0.1). Treatment did not affect the total mammary-gland weight, expressed as a proportion of final body weight. Neither the diameter nor the number of fat cells in kidney–pelvic fat and the MGFP were affected by dietary protein or β-agonist. Results indicate that the β-agonist is effective in the control of fat deposition other than that in the MGFP in rapidly growing female lambs. However, there was no apparent effect of dietary protein on adipose tissues. Key words: Lambs, β-agonist, dietary protein, fat deposition
The effect of dietary herring meal on the omega-3 fatty acid content of plasma and egg yolk lipids of laying hens
Authors: Nash D. M. , Hamilton R. M. G. , Hulan H. W.
Published: March 2010

The effect of dietary HM on plasma and egg yolk lipids of commercial White Leghorn hens was studied over 350 d. A total of 192 birds were given corn-wheat-soybean meal diets that contained either 0, 4, 8, or 12% HM. Analysis of plasma lipids at four periods in the laying cycle (169, 211, 253 and 287 d) and at five times during the test day (0800, 1000, 1200, 1400 and 1600 h) were performed. Egg lipids were analyzed at each of the four periods.Plasma total lipids were inversely related (P < 0.01) to dietary HM levels while omega-3 and omega-6 fatty acid levels were positively and inversely related (P < 0.001), respectively. HM levels did not influence the total lipid content of the egg yolk lipids but omega-3 and omega-6 fatty acid content were positively and inversely related, respectively. The levels of eicosapentaenoic (20:5n3, EPA) and docosahexaenoic (22:6n3, DHA) acid were 11 and 3 times higher, respectively (7.8 and 100.5 mg yolk−1) in the yolks from hens given the 12% HM diet compared to the control diet. Key words: Herring meal, laying hens, omega-3 fatty acids, eicosapentaenoic acid, docosahexaenoic acid
Vitamin A in milk of ewes
Authors: Batra T. R. , Hidiroglou M.
Published: March 2010

Eighteen ewes were randomly assigned to one of the three treatment groups: control, 500 000 IU of vitamin A, and 1 000 000 IU of vitamin A injected, with the objective of evaluating the effect of vitamin A injection on the concentration of vitamin A in the milk. Vitamin A injections were given intramuscularly at lambing and at 35 d after lambing. Milk samples from all ewes in the three groups were collected for the determination of vitamin A at 0, 1, 2, 7, 14, 21, 28, 35, 42, and 49 d after lambing. Ewes injected with vitamin A at lambing had higher concentrations of vitamin A in their milk during the first 7 d of lactation; as a result, an increased amount of vitamin A was available to suckling lambs during their early days of life. The concentration of vitamin A in the milk increased with increase in the dose of vitamin A injection. Colostrum contained a higher concentration of vitamin A than did milk. Milk levels of vitamin A were also increased significantly by a second injection of vitamin A given on 35 d of the lactation, and this effect lasted up to 7 d after the injection. Key words: Vitamin A, milk, ewe
Fatty acid composition of milk fat from three breeds of dairy cattle
Authors: DePeters E. J. , Medrano J. F. , Reed B. A.
Published: March 2010

The proportion of MCFA in milk fat was lowest for Holstein, highest for Jersey, and intermediate for Brown Swiss cows. Proportions of SCFA (C4:0 to C8:0) and LCFA (> 18 C) did not differ among breeds. Differences in fatty acid composition among breeds were small, but could contribute to differences in manufacturing properties of milk fat. Key words: Holstein, Jersey, Brown Swiss, milk fatty acids
Effect of time of grazing or cutting and feeding on the incidence of alfalfa bloat in cattle
Authors: Hall J. W. , Majak W.
Published: March 2010

More bloat occurred after early than after late morning feeding. Cattle were either grazing or fed cut alfalfa (Medicago sativa L.) for 4 h once a day. Rumen chlorophyll concentrations were higher before the early feeding. There were no consistent differences in plant DM, ADF, NDF, chlorophyll or total or soluble N. Key words: Cattle, bloat, legumes, Medicago sativa L.
Effets des tensions sinusoïdales normales et des trains d'impulsions sur le comportement et la production des poules pondeuses
Authors: Vidali G. , Silversides F. G. , Boily R. , Villeneuve P.
Published: March 2010

The effects of normal sinusoidal electrical voltages and impulses on laying hens between 23 and 48 wk of age were evaluated. One hundred and twenty hens were caged individually in six blocks of 20 animals each. Within each block, the treatments were distributed in a randomized complete blocks design. Electrical voltages of constant amplitude of 0–3 V, 4–6 V and 7–9 V were applied in exp. 1, 2 and 3, respectively. Voltage differences with random amplitudes of 0–9 V were applied at a frequency of one pulse every 10 s in exp. 4 and a frequency of two pulses every 10 s in exp. 5. In exp. 6, the hens were subjected to voltages of 12–18 V at a frequency of one pulse every 10 s. In exp. 7, hens were placed three per cage and received either 0 or 12 V with one pulse every 10 s. All voltages were applied between the metallic nipple drinker and the metallic cage. Daily water and feed intake, laying rate and behavior of the hens were measured. These voltages did not affect feed or water consumption, laying rate or egg quality. Frequency of eating and drinking behavior, time spent eating and drinking and time spent standing or sitting were not affected by the treatment. Although poor performance of farm animals is occasionally attributed to stray electrical voltages, in this experiment, voltage differences as high as 18 V had no effect on the hens' production and behavior. Key words: Laying hens, stray voltage, behavior, production performance
Efficacy of Pediococcus pentosaceus for alfalfa forage exposed to precipitation during field wilting
Authors: Wittenberg K. M.
Published: March 2010

The objective of the current study was to determine the preservation potential for an inoculant containing two strains of Pediococcus pentosaceus for forage that had been exposed to precipitation during the wilting phase. Forage was exposed to 26.4 mm precipitation and moderate drying conditions prior to being baled at 20–25% moisture without (Wet) or with Pediococcus pentosaceus (Wet-PP) application at the time of baling. A third hay treatment consisted of forage exposed to 27.6 mm precipitation and baled at 15–20% moisture without inoculant application (Dry). Contrary to results from previous studies with good drying conditions, application of Pediococcus pentosaceus at a rate of 105 cfu g−1 forage did not reduce extent of fungal invasion during storage as determined by storage temperature, glucosamine change, post-storage visual scores and fungal populations. Two wilting trials were conducted to determine the effect of exposure to precipitation during the wilting phase on the indigenous microbial population on the surface of forage material. Forage that was not exposed to precipitation during drying had total bacteria, lactic acid bacteria and total fungal populations ranging from 105 to 106, from 101 to 103, and from 104 cfu g−1 forage DM, respectively, at the time of baling. Exposure to precipitation resulted in population ranges of 107–108, 103–105, and 104–105 cfu g−1 forage DM, respectively. Total bacterial populations increased significantly due to exposure to precipitation. Utilization of a bacterial inoculant at 105 cfu g−1 forage may not be an adequate application rate when the density of the indigenous population on the forage surface is 100–1000 times greater. Key words:Pediococcus pentosaceus, hay, storage, mold, bacteria
The effect of level of diet intake after mating on the serum concentration of thyroxine, triiodothyronine, growth hormone, insulin and glucose, and embryonic survival in the gilt
Authors: Dyck G. W. , Kennedy A. D.
Published: March 2010

Two experiments were undertaken to determine whether there was a relationship between embryo survival and the blood serum concentration of thyroxine (T4) triiodothyronine (T3), growth hormone (GH), insulin (INS), glucose (Glc) and progesterone (P4), as influenced by diet intake. In exp. 1, serum concentrations of T4, T3, INS, Glc and P4 were measured in samples collected at 0.0 (preprandial), 0.33, 0.67, 1.0, 1.5, 2.0, 3.0, 5.0 and 7.0 h (postprandial) on days 7, 11, 15 and 25 of gestation. In exp. 2, 16 control (C) gilts gained 0.49 ± 0.04 kg d−1, while 19 restricted (R) gilts were fed at the same level, except from days 1 to 10 after mating, when diet intake was restricted to 50% of the C gilts. The R gilts from days 0–10 and days 10–20 gained −0.01 ± 0.05 kg d−1 and 0.59 ± 0.06 kg d−1, respectively. Gilts were bled at 5 h postprandial on days 1, 4, 7, 9, 11, 13, 15, 20 and 25, and eight samples were collected on days 7, 11, 15 and 25, from 0–5 h postprandial. Embryo survival was expressed as a percentage of the number of corpora lutea. In exp. 1, T4 and T3 concentrations on day 7 were greater than those on days 11 and 15 (and day 25 for T4). The INS profile was not affected by day of gestation, while Glc profiles differed for days 7 and 25. In exp. 2, a day-of-gestation effect was observed for T4 and T3, with elevated levels on days 1 and 4. Postprandially, T4 increased by 20 min and remained constant, while T3 peaked at 1.5 h; GH showed no change; and INS peaked at 1 h. The INS peak for R gilts was lower on day 11, and GH concentration was lower for R gilts on days 7, 11 and 15. Correlations were only consistently significant between T4 and T3, and between INS and Glc, and for days 1–11 for progesterone with T4 and T3. Correlations of hormone concentrations with embryo survival were generally not significant. These results show that T4 and T3, GH and INS responded differently to the day of early gestation and to diet intake. There were no changes in hormone concentration that could be associated with embryo survival. Key words: Pregnant gilts, diet intake, metabolic hormones
The relationship of plasma somatomedin (IGF-1) to lamb growth rate
Authors: Mears G. J.
Published: March 2010

Somatomedin (IGF-1) was measured in plasma samples obtained from lambs undergoing SRIF immunization to improve their rate of growth. Weight gains and blood samples were obtained at predetermined intervals between weaning and slaughter for a total of 78 crossbred ewe, ram and wether lambs in three experiments. Plasma IGF-1 concentrations were not altered by SRIF-immunization despite improved rates of gain in wether and ram lambs. Ewe, wether and ram lambs had similar plasma IGF-1 concentrations until 12 wk old. After 12 wk of age, ram lamb IGF-1 plasma concentrations were significantly higher than those of ewe and wether lambs. Fasting lambs for 24 h reduced plasma IGF-1 concentrations, having the greatest effect on heavier lambs. When lambs were allowed free access to feed, plasma IGF-1 concentrations obtained between 7 and 18 wk of age were positively correlated, both with weight gains prior to sampling, and with total weight gain from weaning to slaughter. Thus, at each age examined, lambs with higher than average plasma IGF-1 concentrations weighed considerably more than average at slaughter. This indicates that plasma IGF-1 concentrations obtained at an early age may be useful indicators of growth potential and aid in the selection of fast growing animals. Key words: Somatomedin, IGF-1, lambs, growth rate, somatostatin immunization
Vasoactive intestinal polypeptide inhibits electromyographic activity of the reticulo-omasal orifice in meal-fed sheep in warm and cold environments
Authors: Okine E. K. , Miaron J. O. O. , Cosgrove S. , Christopherson R. J.
Published: March 2010

The effects of intragastric arterial infusions (1 mL min−1) of physiological saline, vasoactive intestinal polypeptide (VIP) or VIP-antagonist [4Cl-D-Phe6, Leu17] VIP (1 nmol mL−1) on electromyographic (EMG) activities of the reticulum and reticulo-omasal orifice (ROO) in conscious, solid, meal-fed ewes kept in either warm (18 °C) or cold (1 °C) environments were studied. Infusions were of 15 min duration before, during and after feeding in both environments. In each ruminoreticular cycle the ROO showed long bursts of EMG activity coincidental with reticular EMG activity. Quiescence of the ROO was never fully observed until the reticulum relaxed. The frequencies of reticular bursts in both environments were higher during the period of active eating than during the post- and prefeeding periods. Infusion of VIP in the warm but not in the cold environment reduced frequency of reticular EMG. Compared with saline and antagonist, VIP increased the mean duration of the ROO quiescence to 13 s in the cold environment and to a significantly lower mean of 9 s in the warm environment. We conclude that 1) VIP mediates relaxation of the ROO in solid, meal-fed sheep, 2) ROO EMG activity is influenced by different environments and by phases of the feeding cycle, and 3) the inactivity of the ROO (relaxation) is not coincidental with the reticular EMG bursts in solid-meal-fed sheep. Key words: Sheep, VIP, reticulo-omasal orifice, EMG activity, warm and cold environments
Method for close arterial infusion of the lactating mammary gland
Authors: Maas J. A. , Cant J. P. , McBride B. W. , Trout D. R. , Poppi D. P.
Published: March 2010

A simple method of catheterizing an artery which supplies the ipsilateral side of the mammary gland of a high-producing dairy cow is described. The preparation allows infusion of the mammary gland with nutrients or endocrine factors locally, but does not require general anaesthesia or deep surgical dissection. Following a preliminary experiment involving infusion of acetate, the catheters were removed and the cows returned to the milking herd. Key words: Cow, mammary gland, arterial infusion, acetate
Supplemental chromium and niacin for stressed feeder calves
Authors: Chang X. , Mowat D. N. , Mallard B. A.
Published: March 2010

The effects of supplemental inorganic chromium (Cr) and (or) nicotinic acid (niacin) were compared with those of an organic source of Cr on performance, morbidity and blood metabolites were investigated of 135 crossbred steer calves, purchased at three sales in Ontario. Calves of 236-kg average weight were randomly assigned to control, 0.75 mg kg−1 (dry matter) organic Cr from Cr yeast, 0.75 mg kg−1 inorganic Cr from CrCl3∙6H2O, 100 mg kg−1 niacin, or CrCl3∙6H2O + niacin for the 28-d stress and 28-d growing periods. During the first 2 wk Cr supplementation was doubled. The basal diet was 75% alfalfa silage, 23% high-moisture corn and 2% mineral and vitamin supplement. Treatments had no beneficial effect on overall morbidity. Inorganic Cr and niacin alone had no beneficial effect (P > 0.10) on performance. Inorganic Cr and niacin used together, however, tended to increase weight gain by 39% (P = 0.09) and feed efficiency by 47% (P = 0.08) during the 28-d stress period, with no improvement during the later growing period. Inorganic Cr together with niacin increased serum iron concentration (P = 0.01) and serum total iron-binding capacity (P = 0.01) of healthy calves but had no effect on these metabolites in morbid calves. This study suggested that supplemental inorganic Cr is not as effective as an organic source for ruminants. Supplemental inorganic Cr with niacin tended to improve performance of stressed calves, suggesting that niacin may be a limiting factor for absorption and (or) use of inorganic Cr. Key words: Chromium, niacin, stressed calves, iron, iron-binding capacity, cortisol
Avoparcin and monensin effects on the digestion of nutrients in dairy cows fed a mixed diet
Authors: Haïmoud D. Ali , Vernay M. , Bayourthe C. , Moncoulon R.
Published: March 2010

An in vivo study was carried out to evaluate the effect of avoparcin on fiber, starch and nitrogen (N) digestion compared with monensin. Three dairy lactating cows with ruminal, duodenal and ileal cannulas were used in a 3 × 3 Latin square design. Cows were fed three diets; the control diet had no additive, and the others contained 33 ppm of either avoparcin or monensin-sodium. There were no treatment effects on ruminal pH and total volatile fatty acid levels; molar proportion of propionate tended to be higher (27.9–29.9 vs. 23.7%) and of butyrate tended to be lower (9.9–12.9 vs. 15.4%) for the antibiotic-supplemented diets. Also, both additives decreased ruminal ammonia N concentration (77.2–105.6 vs. 164.1 mg L−1). The supply of avoparcin or monensin reduced the ruminal breakdown of fiber (36.1 and 37.1 vs. 45.9%) starch (57.4 and 54.7 vs. 63.6%), and dietary N (59.5 and 53.6 vs. 67.3%); efficiency of bacterial protein synthesis was unchanged. Passage of bacterial N to the small intestine was not modified; flows of fiber, starch, nonammonia N and dietary N were improved by the both additives. In comparison with the control, monensin caused a greater quantity of glucose (2100 vs. 1500 g d−1) and total amino acids (AA) (1381 vs. 1047 g d−1) to be digested in the small intestine; avoparcin had a less pronounced effect on the intestinal absorption of glucose (1700 g d−1) and AA (1152 g d−1). Only monensin increased the plasma glucose levels (3.6 vs. 3.1 mM). Both additives did not affect total tract digestibilities of organic matter, fiber, starch, and N. Postruminal digestion of fiber was greater (16.0 vs. 7.3%) for antibiotic-supplemented diets, compensating for the lower forestomach digestion. In comparison with monensin dietary avoparcin had a less pronounced effect on the alteration of nutrient digestion. Key words: Avoparcin, monensin, rumen, intestines, amino acids, digestion, cattle
Effect of a mixture of salts of carboxylic acids on silage conservation, voluntary intake and growth rate of cattle fed grass silages
Authors: Charmley E. , McQueen R. E. , Veira D. M. , Berthiaume R.
Published: March 2010

A mixture of carboxylic salts (CS) was used to restrict the extent of fermentation in predominantly grass silages. In trial 1, wilted annual ryegrass/red clover [292 g dry matter (DM) kg−1] was ensiled without additive or after application of 8 L carboxylic salts t−1 fresh forage at ensiling. After 5 mo storage in a plastic silo tube, silages were offered to growing Holstein steers ad libitum, either alone or with 2 kg barley d−1 for 70 d. Use of CS restricted the extent of carbohydrate fermentation and protein solubilization compared with the untreated silage. When fed to steers, CS-treated silage resulted in higher intakes and body weight (BW) gains. Barley supplementation increased total DM intake, but reduced silage intake. Feeding barley increased BW gain. Feed conversion efficiency was improved by CS in unsupplemented silages but not in supplemented silages. In trial 2, first-cut, wilted orchardgrass/red clover was ensiled at 283 g DM kg−1 either with formic acid (FA) at 2 L t−1 or CS at 3.5 L t−1 in bunker silos. The regrowth was ensiled at 304 g DM kg−1 either with FA at 4 L t−1 or CS at 5.3 L t−1 in heap silos. Both CS- and FA-treated first-cut silages underwent butyric acid fermentations. Both second-cut silages were well preserved. Relative to the FA treatment, CS had little influence on fermentation or protein solubilization of the ensiled grass. When fed to growing heifers, intake and BW gains were less for first-cut than second-cut silages. There was no effect of additive on DM intake or BW gain, but feed to gain ratio was better in heifers fed CS-treated than FA-treated silage for both cuts. Carboxylic salts were effective at restricting fermentation and protein solubilization in silage which was beneficial to animal performance. Key words: Grass, silage additive, carboxylic salts, growth, beef
Saccharomyces cerevisiae and Aspergillus oryzae, used alone or in combination, as a feed supplement for beef and dairy cattle
Authors: Chiquette J.
Published: March 2010

The effects of addition of direct-fed microbials prepared from Saccharomyces cerevisiae (SC) and Aspergillus oryzae (AO) to ruminant diets was examined in two experiments. Experiment 1 was designed to study the effects of microbial supplements on ruminal and total tract digestibility, ruminal fermentation, bacterial counts and bacterial colonization of fibrous feed, in eight ruminally cannulated steers. The steers were used in a factorial arrangement within a replicated, concurrently run 4 × 4 Latin square design. Treatments were: (1) 60% rolled barley + 40% timothy hay (C); (2) C + 10 g head−1 d−1 of SC; (3) C + 3 g head−1 d−1 of AO fermentation extract; (4) C + 10 g head−1 d−1 of a mixture of SC and AO. In exp. 2, milk yield and composition were monitored following the addition of microbial supplements to the diets described above and fed to dairy cows. The addition of AO, alone or in combination with SC, stimulated (P < 0.10) ruminal fermentation with higher concentrations of acetate (P < 0.01), propionate (P = 0.07), and total VFA (P < 0.01) when sampled prior to feeding. Accordingly, ruminal pH was lower (P < 0.01) in animals receiving AO, alone or combined with SC. Aspergillus oryzae, when supplemented alone, tended (P > 0.10) to increase ruminal NH3-N concentration. These changes in ruminal fermentation did not affect DMI or ruminal and total tract digestibility. The addition of direct-fed microbials did not affect bacterial counts or bacterial colonization of roughage in the rumen. Milk yield, milk composition and feed intake were not affected by the addition of SC to the diet of dairy cows. However, supplementation of the diet with AO alone or in combination with SC increased (P < 0.05) the ratio of milk yield/DMI. Key words: Direct-fed microbials, Saccharomyces cerevisiae, Aspergillus oryzae, ruminal fermentation, milk production, beef, dairy cattle