bluuebunny/crossref_metadata_2025 huggingface dataset:
Residual feed intake and body composition in young growing cattle
Authors: Basarab J. A. , Price M. A. , Aalhus J. L. , Okine E. K. , Snelling W. M. , Lyle K. L.
Published: April 2011

Crossbred steers (n = 176), 7–8 mo of age and from the five BeefBooster strains (M1, M2, M3, M4 and TX), were used to determine the relationships between residual feed intake (RFI) and growth rate, body composition and heat production (HP), and to quantify differences in RFI independent of differences in body composition. Animals with different RFI levels were also characterized for growth, carcass and body compositional traits. Steers from each genetic strain were selected at random and serially slaughtered on 5 pre-selected days of the finishing period. Steers grew at 1.52 (SD = 0.22) kg d-1 and had dry matter intake (DMI) of 8.5 (SD = 1.0) kg d-1 during the last 71 to 183 d before slaughter. Metabolic mid-point weight, average daily gain (ADG), gain in empty body fat and gain in empty body water accounted for 67.9, 8.6, 3.9 and 1.1%, respectively, of the variation in actual feed intake. Similarly, metabolic mid-point weight (68.5%), ADG (8.2%), gain in ultrasound backfat thickness (1.8%), gain in ultrasound marbling score (1.1%) and year (1.3%) accounted for 80.9% of the variation in actual feed intake. Residual feed intake adjusted for differences in estimated composition of gain (estimated gain in empty body fat and water; RFIII) ranged from -2.06 kg d-1 to +1.61 kg d-1 (SD = 0.60 kg d-1). Residual feed intake adjusted for live animal measures of body composition (gain in ultrasound backfat thickness and marbling score; RFIIII) ranged from -2.11 kg d-1 to +1.88 kg d-1 (SD = 0.62 kg d-1). Low RFIIII animals (efficient) had 6.0% lower metabolizable energy intake (MEI), retained 9.3% less energy and had 4.5% lower HP than medium RFIIII animals (P < 0.01). Low RFIIII animals also had 10.2% lower MEI, retained 12.0% less energy and produced 9.3% less heat than high RFIIII animals (P < 0.01). Liver (P <0.01), small and large intestine (P = 0.09) and stomach and intestine (P < 0.01) weights were less in low and medium RFIIII steers compared to high RFIIII steers. There was a trend for low RFIIII steers to have less dissectible carcass fat (P = 0.08), intermuscular fat (P = 0.06), body cavity fat in the butt and loin (P = 0.01), faster accretion rate of empty body water (P = 0.04) and a slower accretion rate of empty body fat (P < 0.01) than medium and high RFIIII steers. A portion of the greater MEI by high RFIIII steer was accounted for by differences in the chemical composition of gain. However, a greater proportion was due to a disproportionate increase in the energy required for maintenance and heat increment of feeding in high RFIIII steers. An attempt should be made to adjust RFI for changes in the chemical composition of gain, possibly by the inclusion of ultrasound backfat thickness and marbling score into the equation for determining RFI. Key words: Cattle, feed efficiency, residual feed intake, remote sensing, GrowSafe System
Effects of feeding wheat middlings on production, digestibility, ruminal fermentation and carcass characteristics in beef cattle
Authors: ZoBell D. R. , Goonewardene L. A. , Olson K. C. , Stonecipher C. A. , Wiedmeier R. D.
Published: April 2011

Studies were conducted to compare the feed value of wheat middlings (WM) to cereal grains in rations with varying concentrate to roughage levels. In two separate studies, weaned heifers and steers were fed corn silage/alfalf a hay-based growing diets where the concentrate source was either a control diet consisting of rolled barley (heifers) or rolled corn (steers) versus WM, over an 84-d period. In a 107-d study, finishing steers were fed treatments that consisted of rolled corn (C) plus either 35% wheat middlings (WM35) or 50% wheat middlings (WM50). A single cross-over designed digestibility study was also conducted utilizing four cannulated yearling heifers fed either a corn or WM50 diet from the finishing steer study. Results from the heifer and growing and finishing steer studies showed that average daily gain (ADG), dry matter intake (DMI) and feed efficience (FE) were not affected (P > 0.05) by feeding treatment. Carcass characteristics, including hot carcass weight, ribeye area, backfat, yield, quality grade and cutability were also unaffected (P > 0.05) by feed treatment. Results from the digestibility studies indicated total volatile fatty acids (VFA) were increased (P = 0.023) in the WM diet, with acetate lower (P = 0.0003) than the C group, and pH levels of 5.81 and 5.55 for the C and WM treatments respectively (P = 0.011). Dry matter and ADF digestibilities were not affected (P > 0.05) by feed treatment. It is concluded from these studies that WM can be fed to growing beef heifers and steers as an alternative to more traditional concentrate sources such as corn or barley. Wheat middlings could replace up to 50% of the concentrate in a finishing ration. However, certain ruminal fermentation characteristics such as pH, acetate: propionate ratio and total volatile fatty acids may be altered, which could affect performance over an extended feeding period. Key words: Wheat middlings, average daily gain, feed efficiency, digestibility, ruminal degradation, beef cattle
Fatty acids in forages. I. Factors affecting concentrations
Authors: Boufaïed H. , Chouinard P. Y. , Tremblay G. F. , Petit H. V. , Michaud R. , Bélanger G.
Published: April 2011

When forages represent a high proportion of ruminant diets they provide a significant quantity of fatty acids (FA). Effects of growth stage, fertilization, conservation method, growth period, species, and cultivar on forage FA were determined in four experiments. Concentrations of C16:0, C18:2, C18:3, and total FA (TFA) in timothy (Phleum pratense L.) decreased (P < 0.01), respectively, by 15, 16, 31, and 23% between stem elongation and early flowering. Nitrogen fertilization (120 vs. 0 kg N ha-1) caused an increase (P < 0.01) of 18% of C16:0, 12% of C18:2, 40% of C18:3, and 26% of TFA concentrations. Phosphorus was not deficient and P fertilization (45 vs. 0 kg P ha-1) had no significant effect on timothy FA concentrations. Wilting and drying decreased (P < 0.01) timothy C18:2, C18:3, and TFA concentrations. Concentrations of C18:2, C18:3, and TFA were higher in summer regrowth than in spring growth, primarily in orchardgrass (Dactylis glomerata L.) and timothy (P < 0.01). Significant variation for all FA concentrations was observed among 12 species (P < 0.05); on average, the C18:3, C18:2, and C16:0 accounted for 88% of TFA in studied species. Timothy was the only species in which the difference among cultivars was simultaneously significant (P < 0.05) for concentrations of C18:2, C18:3, and TFA. Among the grasses, an annual ryegrass (Lolium multiflorum Lam.) cultivar had the highest C18:3 concentration (20.6 mg g-1 DM) whereas a timothy cultivar had the lowest (7.3 mg g-1 DM) (P < 0.05). Among legumes, a white clover (Trifolium repens L.) cultivar had the highest C18:3 concentration (16.5 mg g-1 DM) whereas an alfalfa (Medicago sativa L.) cultivar had the lowest (6.0 mg g-1 DM) (P < 0.05). Polyunsaturated FA concentrations in forages can be increased by harvesting timothy at an early stage of development and as fresh grass, by increasing N fertilization of timothy, and by choosing species with higher FA concentrations such as white clover and annual ryegrass. Key words: Fatty acids, forages, species, cultivar, growth stage, conservation methods
Fatty acids in forages. II. In vitro ruminal biohydrogenation of linolenic and linoleic acids from timothy
Authors: Boufaïed H. , Chouinard P. Y. , Tremblay G. F. , Petit H. V. , Michaud R. , Bélanger G.
Published: April 2011

Polyunsaturated fatty acids from forages are hydrogenated in the rumen and this biohydrogenation depends on several factors. The objective of this study was to determine and compare in vitro ruminal biohydrogenation of linolenic (C18:3) and linoleic (C18:2) acids in timothy harvested from different growth stages, produced with or without fertilization, or conserved by different methods. In exp. 1, timothy was grown with (120 kg ha-1) and without N and harvested at four growth stages. In exp. 2, harvested timothy was conserved as fresh grass, wilted grass, dry hay, haylage, and silage, some with additives: haylage with lactic acid bateria (LAB), haylage with formic acid, silage with LAB, and silage with formic acid. Samples were incubated with rumen fluid in three trials to compare: (1) samples from exp. 1; (2) the five basic conserving methods of exp. 2, and; (3) how the silage additives affected biohydrogenation of C18:3 and C18:2. Effective disappearances and ruminal bypass of C18:3 and C18:2 were fastest in timothy harvested at stem elongation but slowed linearly with increasing maturity (P < 0.01). Although N fertilization increased (P < 0.01) the effective disappearance and bypass of C18:3 and the bypass of C18:2, it did not affect their rate of disappearance. These last rates were not affected by maturity, but were faster in haylage and silage than in hay (P < 0.01). Ruminal bypass of C18:3 was greater in fresh grass, wilted grass, and dry hay than in haylage and silage (P < 0.01). Additions of formic acid and LAB to haylage and silage had no significant effect on C18:3 and C18:2 disappearances and bypass. To maximize the amount of C18:3 that bypasses ruminal biohydrogenation timothy should be fertilized with N, harvested at an early growth stage, and conserved as dry hay. Key words: Biohydrogenation, fatty acids, N fertilization, maturity, conservation methods, timothy
Savaging behaviour in gilts and sows
Authors: Harris M. J. , Li Y. Z. , Gonyou H. W.
Published: April 2011

This study investigated the effects of parity, prior experience, and environmental conditions on the incidence of savaging on seven commercial farms. Results indicated that 3.40% of gilts and 1.22% of sows killed one or more piglets (P < 0.05). Fourteen percent of sows that savaged as gilts also savaged during their second farrowing, compared to 0.8% of sows that had not reviously savaged. The incidence of savaging was similar among gilts during the first (all gilt herd) and second (gilt/sow herd) farrowing cycles. Key words: Savaging, gilts, sows, pigs, maternal behaviour
The effects of modified carcass chilling on beef carcass grade and quality of several muscles
Authors: Janz J. A. M. , Aalhus J. L. , Robertson W. M. , Dugan M. E. R. , Larsen I. L. , Landry S.
Published: April 2011

To determine the effect of modified carcass chilling on beef carcass grade and meat quality, paired sides were assigned to modified (5°C for 24 h then 0–2°C until 48 h post-mortem) or control chilling (0–2°C for 24 h). After grading at the completion of respective chilling treatments, the longissimus lumborum (LL), longissimus thoracis (LT), semimembranosus (SM), semitendinosus (ST), and infraspinatus (IS) were removed and evaluated immediately or aged for 7, 15, 21, or 29 d prior to evaluation. Estimated cutability was not affected by chill treatment. Modified chilled sides tended (P = 0.15) to have greater marbling scores than control with ~65% having scores 10–110 units greater than control. In ~15% of paired sides, this difference was sufficient to result in upgrading from Canada AA to Canada AAA. Modified chilling reduced mean shear value across all muscles, with these early effects persisting throughout ageing in the LL and LT and represented a savings of at least 7 d of refrigerated ageing time. Neither modified chilling nor ageing could be relied upon to produce consistently tender meat in the SM and ST. Prior to ageing the IS was the most tender muscle and underwent gradual but significant tenderization during ageing. Since tenderness is the most important meat quality trait, industry adoption of cut specific ageing, combined with modified carcass chilling, would appear to be beneficial to ensure consistent and high-quality beef. Key words: Marbling, ageing, tenderness, beef carcass chilling
Effect of low and high forage diet on enteric and manure pack greenhouse gas emissions from a feedlot
Authors: Boadi D. A. , Wittenberg K. M. , Scott S. L. , Burton D. , Buckley K. , Small J. A. , Ominski K. H.
Published: April 2011

The objectives of this study were to assess enteric methane (CH4) production by beef steers fed one of two isocaloric diets with different forage:grain ratios and to quantify greenhouse gas (GHG) emissions from bedded manure packs in the eight feedlot pens holding these steers (14 head pen-1). Five animals (252 ± 20 kg) in each pen were randomly selected for measurement of CH4 emissions over the course of the 126-d feeding trial. Two 24-h gas collections were completed for each steer in each of three collection periods using the sulfur hexafluoride tracer gas technique. The fluxes of nitrous oxide (N2O), methane (CH4) and carbon dioxide (CO2) from bedding packs were measured using vented static chambers in each sampling period. Methane production (L d-1) was 42% higher (P < 0.05) from steers fed the low forage:grain ratio than from steers fed the high forage:grain ratio. Overall, methane production (% of gross energy intake) ranged from 0.9 to 6.9% on the low forage:grain diet and from 0.7 to 4.9% on the high forage:grain diet. Daily CH4 emissions were similar in the first two periods and increased during the third sampling period. There was no effect of diet on manure pack temperature during sampling, however, the manure pack was deeper (P < 0.05) in pens holding animals fed the high forage:grain diet. Furthermore, diet had no effect on the manure pack fluxes. Total daily non-CO2 emissions from enteric and manure pack sources (CO2 equivalent) were different (P < 0.05) between dietary treatments and averaged 1931 ± 81 g head-1 d-1 for the low forage:grain and 1394 ± 81 g head-1 d-1 for the high forage:grain diet. Key words: Feedlot steers, greenhouse gases, enteric fermentation, manure packs
Development of Pichia pastoris as a rumen escape vehicle for the intestinal delivery of recombinant proteins in ruminants
Authors: Strauss C. E. , McAllister T. A. , Selinger L. B.
Published: April 2011

The effectiveness of cellular encapsulation as a method for delivery of bioactive proteins and limiting amino acids to the small intestine of ruminants was investigated. Intracellular expression of green fluorescent protein variant (GFPuv) in Pichia pastoris was used as a visible marker to assess the cellular integrity of P. pastoris and determine the potential of this approach for protecting recombinant proteins from microbial proteolysis in the rumen. Fluorescent cells were easily identified in the presence of strained ruminal fluid when viewed by epifluorescent microscopy, and intact cells were readily enumerated. Batch cultures with rumen digesta demonstrated that 93, 97 and 25% of P. pastoris cells remained intact after 36 to 48 h of incubation in clarified ruminal fluid, an isolated bacterial fraction, and whole ruminal fluid, respectively. In continuous culture (Rusitec) with a dilution rate of 0.75 d-1, 19% of P. pastoris cells flowed intact from the fermentation vessels. In vitro abomasal simulations demonstrated that 84% of inoculated P. pastoris had lysed within 12 h of incubation, a property that is necessary for the release of encapsulated protein prior to the small intestine. These in vitro studies suggest that P. pastoris may be an effective vehicle for post-ruminal delivery of bioactive proteins in ruminants. Key words: Ruminal escape vehicle, Pichia pastoris, green fluorescent protein, bypass protein
Establishment of consumer thresholds for beef quality attributes
Authors: Aalhus J. L. , Jeremiah L. E. , Dugan M. E. R. , Larsen I. L. , Gibson L. L.
Published: April 2011

Acceptability threshold values for Warner-Bratzler shear (WBS) and trained sensory panel attributes were determined through regression analyses against consumer scores for overall tenderness, juiciness, flavour desirability and overall palatability for both the longissimus lumborum (LL) and semimembranosus (SM) muscles. Although consumers were not as sensitive to changes in tenderness as trained panellists, the relationship between consumer scores and trained panellist scores was moderate (r value = 0.64; P = 0.001). Based on the 50% confidence levels for WBS (7.85 and 8.15 kg for the LL and SM, respectively), 20% of LL steaks and 28% of SM roasts collected from commercial abattoirs and aged 6 d exceeded these thresholds. When assessed on the basis of subjective sensory panel scores for overall tenderness, 25.3% of LL steaks and 39.9% of SM roasts exceeded the 50% confidence level. Clearly, without intervention strategies beyond 6 d of aging, there was a significant portion of beef steaks and roasts which did not meet consumer expectations for tenderness. The fact there was a very poor relationship between tenderness in the LL and SM muscles suggests strategies used by industry to improve tenderness may need to be muscle specific. Key words: Beef quality, consumer, threshold, tenderness, Warner-Bratzler shear
Chemical composition and in situ ruminal nutrient degradability of normal and brown midrib forage pearl millet grown in southwestern Québec
Authors: Mustafa A. F. , Hassanat F. , Seguin P.
Published: April 2011

The objective of this study was to determine the chemical composition and in situ ruminal degradability of normal and brown midrib (bmr) forage pearl millet [Pennisetum glaucum (L.) R. Br.] grown in southwestern Québec conditions. Forage was harvested twice during the season. Relative to normal genotype, bmr millet contained less (P < 0.05) neutral detergent fiber (NDF) and acid detergent lignin and more (P < 0.05) crude protein (CP). Fiber fractions were similar for the two harvests. However, CP content was higher (P < 0.05) in the first than the second harvest. In situ ruminal degradabilities of DM, CP and NDF were all higher (P < 0.05) for bmr than normal forage millet and were not affected by harvest. Key words: Forage quality, pearl millet, ruminal degradability, protein fractions, brown midrib
Efficiency of feed utilisation by livestock — Implications and benefits of genetic improvement
Authors: Arthur P. F. , Herd R. M.
Published: April 2011

Genetic improvement strategies in the past have concentrated on traits associated with outputs. Traits that directly affect input costs, such as those related to the efficiency of feed utilisation, have only recently started to receive some attention. This paper examines the current state of knowledge, benefits and challenges associated with genetic improvement of feed utilisation by livestock. Current information indicates the existence of genetic variation in feed efficiency and moderate heritability for most feed efficiency traits in all livestock species. However, there is a paucity of information on the genetic relationships among feed efficiency traits and other traits at different phases of the production cycle. The challenge is to develop breeding programs that exploit genetic variation in efficiency of feed utilisation to improve whole production system efficiency. The cost of recording feed intake (used to compute feed efficiency traits) is high, making it uneconomical, in some species, to measure feed intake in all potential seedstock animals. However, where a two-stage selection approach has been adopted, the inclusion of feed efficiency traits in genetic improvement schemes has yielded substantial additional benefits over and above the benefits from existing schemes that do not include feed efficiency traits. Under a two-stage selection strategy all potential seedstock animals are first evaluated for the production traits of interest, after which strategically selected individuals undergo feed efficiency testing. Where physiological or genetic markers for feed efficiency exist, such information is included in the first stage selection decision. There is theoretical evidence that selection for some feed efficiency traits, such as residual feed intake, will have additional benefit of reducing greenhouse emissions by livestock and improving environmental sustainability. The challenge is to generate the necessary empirical data to support this assertion. Key words: Feed efficiency, genetics, physiology, economic benefit, environmental sustainability
Responses to climatic variables of horses housed outdoors under Nordic winter conditions
Authors: Mejdell Cecilie M. , Bøe Knut E.
Published: April 2011

The aim of this study was to investigate the responses to cold winter weather of Icelandic horses kept permanently outdoors. The horses were kept in a 0.8-ha enclosure, with free access to grass silage and a shelter. Behaviours were recorded during 23 d using direct observation scan sampling at 20-min intervals between 1600 and 0000, embracing air temperatures down to -31°C. Body condition score, coat length and serum thyroid hormone (T4) level were recorded. Horses spent most of their time outdoors under all weather conditions, and the average incidence of being outdoors was 70%. The horses made more use of the shelter at low ambient temperatures (P < 0.01). There was also a strong tendency for increased use of the shelter in response to rain and wind (P < 0.07). Precipitation as snow had no effect. Shivering was observed once in a single horse, on a rainy day at +5°C. Average maximum neck coat length was 4.6 ± 0.9 cm. Body condition score remained within satisfactory limits during winter. Serum T4 showed no correlation with ambient temperature (P = 0.70). It is concluded that a cold climate with temperatures down to -31°C does not challenge the thermoregulation of cold-acclimated Icelandic horses, provided that there is sufficient quality feed and access to a shelter. Key words: Horse, winter climate, shelter, behaviour, welfare, thyroid hormone
Repeated ruminal dosing of Ruminococcus flavefaciens NJ along with a probiotic mixture in forage or concentrate-fed dairy cows: Effect on ruminal fermentation, cellulolytic populations and in sacco digestibility
Authors: Chiquette J. , Talbot G. , Markwell F. , Nili N. , Forster R. J.
Published: April 2011

Many studies have introduced exogenous bacterial strains into the rumen in an attempt to improve fermentation processes or counteract ruminal digestive disorders. Some attempts have been successful in the establishment of the new strain although others have failed. To a large extent, particular conditions necessary to the establishment of a new strain are not yet fully understood. In the present study, Ruminococcus flavefaciens NJ (NJ), isolated from the rumen of a wild moose, was introduced into the rumen of six ruminally fistulated non-lactating dairy cows receiving either a high concentrate or a high forage diet and supplemented on a daily basis with a probiotic mixture. In a second experiment, NJ and the probiotic mixture were given to young calves of 21 to 35 d of age. During repeated dosing, NJ modified the abundance of other cellulolytic bacterial populations compared with periods with no dosing. NJ also improved in sacco digestibility of timothy hay with the high concentrate diet. NJ declined rapidly in the rumen from 106 cells mL-1 after dosing to 102 cells mL-1, 24 h following dosing. The persistence of NJ increased with weeks of dosing in cows or when introduced in the rumen of young calves (105 cells mL-1 after 48 h and 102 cells mL-1 after 7 d). The presence of probiotics or a change in the concentrate to forage ratio in the diet did not succeed in establishing the new strain in the rumen. Key words: Ruminococcus flavefaciens NJ, probiotics, rumen fermentation, cellulolytic populations, in sacco digestibility, non-lactating dairy cows
Effect of feed texture, meal frequency and pre-slaughter fasting on behaviour, stomach content and carcass microbial quality in pigs
Authors: Saucier L. , Bernier D. , Bergeron R. , Giguère A. , Méthot S. , Faucitano L.
Published: April 2011

In this study, behaviour in lairage, weight and composition of stomach contents and carcass microbial contamination were studied in 96 barrows assigned to the following treatments: feed texture (FT; mash vs. pellets), meal frequency (MF; 2 vs. five meals per day) and fasting time (WT; 4, 14 and 24 h) according to a 2 × 2 × 3 factorial design. Pigs fed two meals had heavier stomach weights at slaughter than those fed five times per day (P = 0.01). An interaction was found between WT and FT (P = 0.002) for stomach weight. With respect to the contamination of the mouth, total aerobic mesophilic counts were higher than 104 cfu cm-2 but not significantly different between treatments. Coprophagy behaviour in lairage was not correlated with mouth contamination at slaughter. The treatment resulting in the lowest Escherichia coli counts on the thoracic area was feeding the pigs pellets five times per day followed by a 24-h fast. In contrast, the highest E. coli counts were observed in pigs fed mash five times per day followed by a 4-h fast. Comparison a posteriori of these two extreme scenarios yielded a P value of 0.03. Key words: Animal behaviour, carcass hygiene, fasting, feeding, pigs, stomach
Effect of intensity of maceration on digestibility and intake of alfalfa hay and silage fed to sheep
Authors: Agbossamey Y. R. , Savoie P. , Seoane J. R. , Petit H. V.
Published: April 2011

A study was conducted to determine the influence of intensity of mechanical conditioning on the nutritive value of alfalfa conserved as hay or silage. Fresh alfalfa was mowed and conditioned at three levels of maceration prior to field wilting during 45 h for silage (29–39% DM) or 94 h for hay (87% DM, after barn-curing), under light rain conditions during the first 2 d. The conditioning treatments were: control (conventional mowing-conditioning), light maceration (one passage through three knurled steel rolls), medium maceration (two passages), and intense maceration (three passages). Concentrations of NDF, ADF, hemicellulose, CP-NDF, and CP-ADF increased linearly (P < 0.001) with the level of maceration. Silage pH, acetic acid, propionic acid, and butyric acid increased, while lactic acid decreased (P < 0.001), with the level of maceration. The effective rumen degradabilities of DM, CP, and NDF, measured with fistulated cows, were not affected (P > 0.10) by the level of mechanical conditioning. Forty-eight male sheep (46.8 ± 6.7 kg BW) were fed a 100% forage diet according to a completely randomized design with a 2 × 4 factorial arrangement of treatments (two storage methods and four levels of conditioning). Under restricted feeding, DM, NDF, ADF, and hemicellulose digestibilities decreased linearly (P < 0.001) with the level of maceration. However, the digestibility of CP-NDF increased with the level of maceration; the effect was more important in hay than in silage (P < 0.001 for the interaction). When silages were fed ad libitum to 24 sheep, daily DMI was 2.31, 2.88, 2.76, and 2.41% of BW and DM digestibility was 60.8, 60.1, 56.2, and 46.7%, for control, light, medium, and intense maceration, respectively (P < 0.01). The results suggest that light maceration increases DM intake while maintaining digestibility of forages fed to sheep. Because of humid conditions and potential soil contamination due to multiple windrow pickup, intense maceration caused severe nutrient loss, which might be avoided under dry field wilting and good storage conditions. Key words: Alfalfa, hay, silage, digestion, degradability, intake
Machine effects on accuracy of ultrasonic prediction of backfat and ribeye area in beef bulls, steers and heifers
Authors: Charagu P. K. , Crews Jr. D. H. , Kemp R. A. , Mwansa P. B.
Published: April 2011

Pre-slaughter ultrasound and carcass measurements of ribeye area (REA) and backfat (FAT) were recorded on composite beef bulls (n = 60), heifers (n = 60) and steers (n = 60). Breed composition of the composite was: 0.44 British (Hereford, Angus and Shorthorn) 0.25 Charolais, 0.25 Simmental and 0.06 Limousin. The Aloka SSD-1100 (AL) and the Tokyo Keiki CS 3000 (TK) ultrasound machines were compared by evaluating the difference between ultrasound and carcass measurements (bias), and the standard error of prediction (SEP). AL under-predicted REA in all three sexes while TK overpredicted heifers and steers and underpredicted bulls. Both machines were similar in accuracy among bulls for REA. For FAT AL underpredicted all three sexes while TK underpredicted heifers and had very small bias for bulls and steers. SEP for FAT were similar for both machines. Both machines underpredicted REA in larger muscled cattle and overpredicted in smaller-muscled cattle. Both machines also underpredicted FAT in fatter animals and overpredicted FAT in leaner animals. Machines were similar in accuracy among cattle with larger REA but differed significantly (P < 0.05) among smaller-muscled cattle. Machines were comparable in accuracy among animals of all FAT sizes. This study demonstrates that there is an important relationship between machine and the size and depth of muscle and backfat, respectively, and consequently between machine and sex, in accuracy of ultrasound prediction. Key words: Beef cattle, ultrasound, accuracy, back fat, ribeye area
Effects of processing and fat content of coarse canola screenings on voluntary intake and total tract nutrient digestibility of beef steers
Authors: Pylot S. , McKinnon J. J. , Mustafa A. F. , Racz V. J. , Christensen D. A.
Published: April 2011

The effects of feeding canola screenings on voluntary intake (VI) and nutrient digestibility by growing steers were determined in two experiments. Twelve steers were involved in the first experiment to study the effects of processing (grinding and pelleting) of canola screenings on VI and apparent total tract dry matter digestibility (DMD), crude protein digestibility (CPD), fatty acid digestibility (FAD), neutral detergent fiber digestibility (NDFD), and acid detergent fiber digestibility (ADFD). In the second experiment, the effects of fat level from canola screenings on VI and total tract nutrient digestibilities were determined using 12 steers. The fat levels tested were 67, 100, 128, and 162 g kg−1 ether extract (EE). Feeding processed canola screenings (176 g kg−1 EE) reduced (P < 0.05) VI by 31% and improved (P < 0.05) DMD, CPD, and FAD by 18, 19, and 28%, respectively. Processing of canola screenings reduced (P < 0.05) ADFD by 15% with no effect on NDFD. Increasing dietary fat level from 67 to 162 g kg−1 reduced VI in a quadratic manner (P < 0.05) and improved NDFD in a linear (P < 0.05) fashion. However, DMD, CPD, and ADFD were not affected by fat level in the diet. Total tract digestibility of fatty acids decreased linearly (P < 0.05) from 822 to 640 g kg−1 with increasing dietary fat level. The results of the study indicate that dietary fat from canola screenings at levels up to 100 g kg−1 can be fed to growing steers without detrimental effects on feed intake. Key words: Canola screenings, fat, intake, nutrient utilization, steers.
Mammary gland biopsy does not affect lactation performance in sows
Authors: Kirkwood R. N. , Pérez Laspiur J. , Ames N. K. , Moore J. B. , Cegielski A. , Trottier N. L.
Published: April 2011

To determine morphological and molecular characteristics of porcine mammary tissue in vivo, mammary tissue was collected from 18 sows at 3 to 6 d of lactation and 17 to 19 d of lactation using a biopsy technique. The success of the technique was determined by monitoring lactation performance, as evidenced by sow rectal temperature, voluntary feed intake, milk somatic cell count, and piglet average daily gain. Up to 1.7 g of mammary tissue was collected at each biopsy without decreasing sow feed intake or piglet growth. Key words: Biopsy, mammary gland, lactation, sow
Methane abatement strategies for cattle: Lipid supplementation of diets
Authors: Beauchemin Karen A. , McGinn Sean M. , Petit Hélène V.
Published: April 2011

A study was conducted to investigate the impact of several lipid sources that supplied mainly long-chain fatty acids (FA), for their potential to reduce methane emissions from growing cattle. Sixteen Angus heifers (initial weight, 325 ± 41 kg) were used in the experiment, which was designed as a crossover with two groups, four 21-d periods, and four dietary treatments: control (no added lipid source), tallow, sunflower oil, and whole sunflower seeds. Lipid sources were added to supply 34 g fat kg-1 of dietary dry matter (DM), bringing the total dietary fat content to about 59 g kg-1 of DM. Adding tallow increased the dietary proportion of saturated FA (47 g 100 g -1 of FA), whereas sunflower oil and seeds decreased the proportion (21 g 100 g-1 of FA). The basal diets consisted of mainly whole-crop barley silage (650 g kg-1 of DM). Compared with the control, ad libitum intake was reduced (P < 0.001) with sunflower seeds, but not with tallow (P = 0.13) or sunflower oil (P = 0.53). About 14% less methane was emitted per animal when diets contained tallow or sunflower oil and 33% less methane was emitted when diets contained sunflower seeds (P < 0.001), compared with the control diet (177.4 g d-1). Relative differences in methane emissions among lipid sources were maintained after correction for intake of DM or gross energy. The methane reduction caused by tallow and sunflower seeds was partly due to decreased diet digestibility. Digestibility of neutral detergent fiber in the total tract decreased (P < 0.05) by 15% with tallow and by 20% with sunflower seeds compared with the control, with only a numerical reduction from control for sunflower oil (12%; P = 0.11). Consequently, digestible energy intake was about 4% higher (P < 0.001) for sunflower oil, but 3% lower (P = 0.02) with tallow and 12% lower (P < 0.001) with sunflower seeds, compared with the control. All lipid sources reduced methane emissions by an average of 17% when corrected for digestible energy intake (from 11.22 to 9.34 g methane Mcal-1; P = 0.01). We concluded that adding about 3% lipid to high-forage diets in the form of saturated or unsaturated long-chain FA decreases methane emissions, and could have substantial effects on methane inventories if implemented commercially. All three lipid sources suppressed methane production, but sunflower oil has good potential for on-farm adoption because it had minimal effects of fiber digestibility, increased the intake of digestible energy and the rate of gain of cattle, and lowered methane production. Although tallow and sunflower seeds are usually cheaper sources of lipid than sunflower oil, their cost effectiveness as methane abatement strategies would also need to account for their potentially negative effects on digestible energy intake and performance of cattle fed high-forage diets. key words: Beef cattle, diet, fat, greenhouse gases, lipid; methane, oil
Effect of lameness on dairy cows’ visits to automatic milking systems
Authors: Borderas T. F. , Fournier A. , Rushen J. , de Passillé A. M. B.
Published: April 2011

Lameness is a major welfare problem for dairy cows and has important economic consequences. On-farm detection of lameness is difficult, and automated methods may be useful for early diagnoses. Lameness may reduce the efficiency of automated milking systems (AMS) if lame cows are less willing to visit the automatic milking unit voluntarily and poor attendance at milking units may help detect lameness. To determine whether a low frequency of visits in an AMS could serve as an indicator of lameness, data on the frequency of visits of 578 cows in 12 AMS on eight farms were collected. From each AMS, 22 cows (from a mean of 54 cows per AMS), were classified as either the 11 highest visitors or the 11 lowest visitors based on the total number of visits to the milking unit. These selected cows (n= 256) were videotaped while walking in a standard test area and their gait scored on a 5-point scale (1 = sound 5 = severely lame). Intra- and inter-observer reliability values between and within observers were high for gait scoring. Significant differences in gait scores between the two groups of cows (P< 0.05) were found in 9 out of 12 AMS: high-visiting cows had better gait scores than low-visiting cows. Four percent of high visitors were classified as slightly lame and 32% of low visitors were classified as either slightly or severely lame. The overall numerical rating score was the most effective in discriminating between high and low visitors, and scoring each individual component of gait did not greatly improve discrimination between the two groups of cows. The frequency that dairy cows visit an AMS is related to their locomotory ability, and data from the AMS may help in the early detection of lameness. Key words: Cattle, lameness, automatic milking systems, behaviour, gait scoring
Relationships between progeny residual feed intake and dam productivity traits
Authors: Basarab J. A. , McCartney D. , Okine E. K. , Baron V. S.
Published: April 2011

Two hundred and twenty-two yearling calves and their dams were used to examine the phenotypic (rp) relationships between progeny residual feed intake (RFI) and maternal productivity across 10 production cycles. Progeny RFI ranged from -3.95 to +2.72 kg as fed d-1 (SD = 0.94), while RFI adjusted for off-test backfat thickness (RFIadj), ranged from -2.48 to +1.53 kg as fed d-1 (SD = 0.88). Progeny RFI and RFIadj were unrelated to on-test age, body weight, growth rate, and ultrasound longissimus thoracis area and positively related to feed intake (rp = 0.51 to 0.53; P < 0.001), feed to gain ratio (rp = 0.44 to 0.46; P < 0.001), feeding behaviour traits (rp = 0.29 to 0.36; P < 0.001) and cow RFI (rp = 0.30, P < 0.05). Progeny RFI was positively related to measures of body fat (rp = 0.21 to 0.27; P < 0.05), but these relationships disappeared when RFI was adjusted for off-test backfat thickness. Cows that had produced LOW (≤ 0.5 SD), MEDIUM (± 0.5 SD) or HIGH (≥ 0.5 SD) RFIadj progeny were similar in pregnancy (95.6 vs. 95.3 vs. 96.0%, P = 0.90), calving (84.9 vs. 83.4 vs. 86.3%, P = 0.62) and weaning (81.5 vs. 80.2 vs. 82.3%, P = 0.79) rates. However, cows that produced HIGH RFIadj progeny had a higher twinning rate (3.77 vs. 0.35 vs. 0.00%, P < 0.001) and an increased calf death loss (8.06 vs. 4.24 vs. 4.02%, P = 0.10) compared with cows that produced MEDIUM or LOW RFIadj progeny. Cow body weight over 10 production cycles was similar at weaning, pre-calving and pre-breeding for dams that had produced LOW, MEDIUM and HIGH RFIadj progeny, and dams that produced LOW RFIadj progeny consistently averaged 2–3 mm more back fat thickness than dams that produced HIGH RFIadj progeny. Calf birth weight, pre-weaning ADG and 200-d weight, and cow production efficiency and calving interval were similar among dams that produced LOW, MEDIUM and HIGH RFIadj progeny. In addition, dams that produced LOW RFIadj progeny consumed less feed during their second trimester of pregnancy (10.9 vs. 11.6 vs. 12.2 kg DM d-1, P < 0.05), had lower RFI values (-0.05 vs. 0.44 vs. 1.88 kg as fed d-1, P = 0.018) and calved later in the year (96 vs. 90 vs. 91 d Julian, P < 0.001) than dams that produced MEDIUM and HIGH RFIadj progeny. These results showed that efficient RFI progeny and dams consumed less feed, had improved feed to gain ratio and spent less time in feed activity than inefficient cows and calves. In addition, cows that produced efficient calves were fatter, had fewer twins, less calf death loss and produced the same weight of calf weaned per cow exposed to breeding compared with cows that produced inefficient progeny. However, cows that produced efficient or low RFI progeny calved 5–6 d later in the year than cows that produced inefficient or high RFI progeny, indicating a need to monitor reproductive fitness in low RFI replacement heifers and breeding bulls. Key words: Residual feed intake, cow reproduction, lifetime production efficiency
Assessment of the potential of feed enzyme additives to enhance utilization of corn silage fibre by ruminants
Authors: Eun Jong-Su , Beauchemin Karen A
Published: April 2011

We hypothesized that the fermentation of corn silage by a mixed culture of rumen microorganisms in an in vitro system could be increased using exogenous fibrolytic enzyme additives (FE), and that the improvement would depend on the dose of cellulase or xylanase activity provided. An in vitro assay was used to determine the effects of FE on gas production (GP) and degradability of fibre after 24 h of incubation in buffered ruminal fluid. Eight FE with endoglucanase and xylanase activities were evaluated at one dose (0.5 mg g-1 of forage dry matter), providing variable units of enzymic activity. Only one product improved fibre degradability (9.1 and 29.9% increases for neutral and acid detergent fibre, respectively; P < 0.05). The FE were reassessed when added to supply the same dose of enzymic activity: 807 units of endoglucanase or 477 units of xylanase activity g-1 of forage dry matter (a unit was defined as nmol of reducing sugar released min-1). The FE had greater impact on GP (21% increase; P < 0.05) and fibre degradation (29 and 60% increases for neutral and acid detergent fibre, respectively; P< 0.05) when equalized for endoglucanase activity than when equalized for xylanase activity. Enzyme products high in endoglucanase activity and low in xylanase activity have the potential to improve the use of corn silage by ruminants. Key words: Corn silage, degradability, exogenous fibrolytic enzymes, gas production
Evaluation of sheep genetic resources in North America: Lamb productivity of purebred, crossbred and synthetic populations
Authors: Shrestha J. N. B. , Boylan W. J. , Rempel W. E.
Published: April 2011

Lamb weights and daily gains from divergent genetic types of established purebreds, e.g., Dorset (D), Lincoln (L), Rambouillet (Ra), Suffolk (Su) and Targhee (T), and fecund-type breeds, e.g., Finnsheep (F) and Romanov (Ro), their reciprocal crosses and Suffolk sired specific cross Su(F × Ro) were evaluated. Also evaluated were lambs of the Outaouais (O) and Rideau (R) Arcott breeds and their reciprocal crosses, in addition to Synthetic I (½ F, ½ L), Synthetic II (½ D, ½ Ra) and Synthetic III (¼ F, ¼ L, ¼ D, ¼ Ra) populations. The established purebreds produced heavier lambs at birth and weaning, Arcott breed crosses gained weight more rapidly resulting in heavier lambs at 140 d, and fecund-type breeds produced lighter lambs (P < 0.05). In general, daily gains and lamb weights of all genetic types were similar, except that fecund-type breeds produced significantly lighter lambs. Lamb weights of T were most at birth, and Su at weaning and 140 d, while F lambs weighed the least (P < 0.05). Within established purebreds, Su weighed the most and D weighed the least, while L, Ra and T lambs were intermediate. Daily gains including weaning and 140-d weights of F and R cross lambs benefited from 7–9% heterosis, while the Arcott breed cross lambs not only benefited from 5–8% heterosis, but were comparable with Su lambs. At the same time, lamb performance of Su(F × Ro) was similar to the average of their parental breeds. Lambs of synthetic populations relative to the average of their respective parental breeds weighed 8–24% more at 140 d, suggesting heterosis retention. Key words: Growth, North American breeds, Finnsheep, Romanov, Arcotts, synthetic populations
Performance and bunk attendance of cattle fed steam-rolled or ground corn supplemented with laidlomycin and chlortetracycline or monensin and tylosin
Authors: Gibb D. J. , Streeter M. , Schwartzkopf-Genswein K. S. , McAllister T. A.
Published: April 2011

British cross steer calves (n = 240; 332 ± 23 kg) in 16 pens were fed ground (G) or steam-rolled (SR) corn-based finishing diets medicated with 12 mg kg-1 laidlomycin propionate and 42.2 mg kg-1 chlortetracycline hydrochloride (LC) or with 30.4 mg kg-1 monensin sodium and 10.5 mg kg-1 tylosin phosphate (MT) in a 2 × 2 factorial experiment. Individual bunk attendance was monitored using radio frequency identification in one pen per diet. Finishing diets were fed for 125 d following a 27-d adaptation from 65 to 91% concentrate diet. In the first 56 d and overall, daily dry matter intake (DMI) was greater (P < 0.05) with LC than with MT (8.8 vs. 8.3 kg), but did not differ (P = 0.97) between G and SR diets. There was a trend (P = 0.11) towards greater ADG for cattle fed LC than those fed MT (1.54 vs. 1.47 kg d-1), but gain:feed was similar (0.169; P = 0.80) between antibiotic supplements. Processing method did not (P = 0.29) affect rate of gain, but SR tended (P = 0.06) to improve gain:feed compared with G (0.171 vs. 0.165). Steers fed LC spent more (P < 0.001) time at the bunk than those fed MT (125 vs. 120 min d-1). On G diets, cattle fed LC made fewer daily visits (9.3 vs. 9.5 visits d-1; P = 0.03), but spent more time at the bunk (135.9 vs. 124.0 min d-1; P < 0.001) resulting in greater duration per meal (15.4 vs. 13.7 min meal-1; P < 0.001). These cattle also had the greatest deviation in daily duration at the bunk (37.3 vs. 33.7 min; P < 0.001). The prevalence of liver abscesses was 13.2% with LC and 6.5% with MT (P = 0.09). However, the prevalence of severely abscessed livers (2.9%) was unaffected (P = 0.45) by treatment. The prevalence of foot rot was greater (P = 0.02) for cattle fed MT (7.5%) than for cattle fed LC (0.8%). Compared with feeding MT, feeding LC may enhance ADG, possibly due to greater DMI. Key words: Beef, chlortetracycline, corn processing, laidlomycin, monensin, tylosin
Effect of wheat type grinding, heat treatment and phytase supplementation on growth efficiency and nutrient utilization of wheat-based diets for broilers
Authors: Afsharmanesh M. , Scott T. A. , Silversides F. G.
Published: April 2011

This experiment studied the effect of phytase and processing (heat treatment, grind size) on performance and nutrient utilization of broilers fed diets from 1 to 21 d that included hardred spring (HRS) and durum wheat with three grind sizes (470, 560, 630 µm) with or without heat treatment (oven dry at 80°C for 15 h) before supplementation with phytase (Natuphos® 0 or 600 FTU kg-1). All 24 diets contained 0.5 g Avizyme 1302 kg-1 and were formulated (80% wheat, 20% basal diet) to supply nutrients necessary to meet the requirements of broiler chicks, except for a low level of nonphytate phosphorus (P, 2.7 g kg-1). The medium ground HRS-based diet produced significantly better feed conversion ratio (FCR) and body weights compared with the other two grind sizes. Heat treatment significantly improved feed conversion ratio and apparent metabolizable energy (AME), protein, and P digestibility of diets. It also significantly decreased feed intake, but produced no differences in 21 d body weight. Supplementation with phytase significantly improved AME, protein, and P digestibility of test diets. The AME of diets was influenced by wheat type, processing and grind size. Phytase increased N and P digestibility. Improvements in N and P digestibility by phytase and heat treatment were dependent on wheat type and grind size.The present results suggest an advantage of both phytase and xylanase in durum- and HRS-based diets. Heat processing destroyed endogenous phytase and xylanase in wheat-based diets, and increased the levels of soluble non-starch polysaccharides. Combined phytase, heat treatment, and grind size may synergistically improve N and P digestibility. Key words: Wheat source, grind size, heat treatment, phytase, digestibility, broiler
Effects of dim light at night on milk yield, milk composition and endocrine profile of lactating dairy cows
Authors: Bal Mehmet A , Penner Greg B , Oba Masahito , Kennedy Alma D
Published: April 2011

The objective of this study was to evaluate the effects of night-time light intensity on lactation performance and hormonal profiles in lactating dairy cattle. Twenty-four multiparous lactating dairy cows were exposed to light intensities of 0 to 5 lx (CONTROL) and 40 to 60 lx (DIM-LIGHT) from 1800 to 0400 in a cross-over design with 28-d periods. Contrary to the pre-trial hypothesis, melatonin release was not suppressed by DIM-LIGHT at night, and treatment effects on milk and milk component yields were not detected. Key words: Dim light, melatonin, milk production