Karrow, N. A., Goliboski, K., Stonos, N., Schenkel, F. and Peregrine, A. 2014. Review: Genetics of helminth resistance in sheep. Can. J. Anim. Sci. 94: 1-9. Gastrointestinal helminth parasites are an important source of economic loss to sheep producers. A rapid increase in anthelmintic resistance has occurred around the globe; therefore, the industry is exploring alternative strategies such as genetic selection to control losses attributed to helminth infection. Since helminths have co-evolved with sheep for millions of years, natural selection for enhanced helminth resistance has occurred within certain breeds from various parts of the world. These breeds of sheep are being used to better understand the genetic aspects of helminth resistance. If the genetic variants that contribute to this phenotype can be identified, it may be possible to use selection strategies to introduce resistance alleles into other breeds or to increase their frequency within breeds. This review will provide an up-to-date overview of the pathology of helminth disease, the immune response to helminth infection, and the search for genes that confer helminth resistance.

Greter, A. M., AlZahal, O., Duffield, T. F., McBride, W. B., Widowski, T. M. and DeVries, T. J. 2014. Effect of frequency of feed delivery on the feeding behaviour, growth, and rumen temperature of limit-fed dairy heifers. Can. J. Anim. Sci. 94: 11-20. The objective of this experiment was to determine the effect that frequency of provision of feed, provided in a restricted amount, had on feeding and lying behaviour, growth, and rumen temperature of growing dairy heifers. Twenty-four Holstein heifers (178.2±9.3 d of age; mean±SD), divided into six groups of four, were assigned to each of three treatments using a 3×3 Latin square design with 28-d periods (21-d adaptation, 7-d data collection). Treatments were delivery of daily allotment of total mixed ration (fed at 2.0% of body weight): (1) once per day (1×; 0800), (2) twice per day (2×; 0800 and 1600), and (3) four times per day (4×; 0800, 1200, 1600, and 2000). Average daily gain (ADG) was similar across treatments (0.8 kg d^-1). There was a tendency for within-pen variation of ADG (average, per pen, of the absolute difference between individual heifer ADG and pen mean ADG) to be greater with 4× (0.3 kg d^-1) and 2× (0.3 kg d^-1) compared with 1× (0.2 kg d^-1). Both feeding (63.1 vs. 44.2 vs. 51.5 min d^-1) and unrewarded (presence at the feed bunk when no feed was present; 49.5 vs. 27.7 vs. 33.1 min d^-1) time at the feed bunk decreased with increasing frequency of feed delivery (1×, 2×, and 4×, respectively). Frequency of displacements (3.1 displacements d^-1) and number of displacements per unit of feeding time (0.06 displacements min^-1) were similar between treatments. Lying time was similar between treatments (802.5 min d^-1), while there was an increase in the amount of time spent standing without eating as frequency of feed delivery increased (558.9 vs. 590.0 vs. 604.7 min d^-1 for 1×, 2×, and 4×, respectively). Thus, feeding 1× d^-1 may prove beneficial for limit-fed heifers as it increases the time spent feeding, and decreases time spent standing without eating and within-pen variation in ADG.

Chapinal, N., Fitzpatrick, C. E., Leslie, K. E. and Wagner, S. A. 2014. Short Communication: Automated assessment of the effect of flunixin meglumine on rumination in dairy cows with endotoxin-induced mastitis. Can. J. Anim. Sci. 94: 21-25. The objective was to evaluate the use of rumination loggers to monitor the effect of flunixin meglumine on rumination in lactating dairy cows with endotoxin-induced clinical mastitis. Mastitis was induced in 13 cows by intramammary infusion of Escherichia coli lipopolysaccharide (LPS) into a rear quarter. Four hours later, seven cows received flunixin meglumine intravenously and six received a saline solution. Control cows ruminated less than treated cows 5-8 h and 11-12 h after LPS infusion, although they ruminated more 15-16 h after LPS infusion. Rumination loggers show promise as a practical on-farm tool to monitor the efficacy of anti-inflammatory therapy for clinical mastitis.

Zhang, P., Wang, Y., Jiang, M., Zhu, L., Li, J., Luo, M., Ren, H. and Liu, L. 2014. Molecular cloning, recombinant protein expression, tissue distribution and functional analysis of a new c-type lysozyme from Lezhi black goat rumen. Can. J. Anim. Sci. 94: 27-34. Three major distinct types of lysozymes have been identified in the animal kingdom and most lysozymes cloned from ruminants belong to the chicken-type (c-type). In this study, a new c-type lysozyme gene, named LZRLyz, was cloned and sequenced from the Lezhi black goat rumen. The LZRLyz cDNA has a 444 bp open reading frame (ORF) encoding a 147 amino acid polypeptide. The encoded polypeptide is predicted to have an 18 amino acid signal peptide, and a 129 amino acid mature protein with an isoelectric point (pI) of 6.08. The LZRLyz amino acid sequence shares 70.27% identity with the Capra hircus blood lysozyme and is grouped with other ruminants c-type lysozymes using the phylogenetic tree estimated by Neighbor-Jointing method. The recombinant expressed LZRLyz protein (pET-rLZR) shows a molecular mass of ~33 kDa, which is consistent with the predicted fusion protein molecular mass and shows antimicrobial activity. Quantitative real-time RT-PCR analyses revealed that LZRLyz transcripts are expressed in all tested tissues with the predominant expression being observed in rumen and the weakest one in spleen. Results of this study suggest that the LZRLyz gene represents a new c-type lysozyme gene that likely functions in Lezhi black goat host immunity and digestive systems.

Vianna, L. L., Pradieé, J., Santos, E. C. S., Gonçalves, A. O., Pfeifer, L. F. M., Rheingantz, M. G. T., Dode, M. A. N., Vieira, A. D., Lima, V. F. H., Correa, M. N. and Pegoraro, L. M. C. 2014. Isolate^® and Optiprep^® minigradients as alternatives for sperm selection in bovine in vitro embryo production. Can. J. Anim. Sci. 94: 35-42. The objective of this study was to evaluate alternatives in small volumes to conventional gradient of Percoll^® on semen quality, in vitro embryo production, sex ratio and embryo survival after vitrification. Thawed semen was randomly allocated to one of four density gradient selection methods: (1) conventional Percoll^® (P), (2) MiniPercoll (MP), (3) MiniIsolate (MI), and (4) MiniOptiprep (MO). Sperm kinetics and quality were evaluated. Use of P, MP and MI gradients did not affect sperm motility (P>0.05). However, there was a decrease in total and progressive sperm motility in MO (70.8 and 51.3% vs. 87.3 and 69.5% for P; 87.3 and 73% for MP; 92.3 and 78.8% for MI; P<0.05). The MO had lower membrane integrity compared with P, MP and MI (39.7 vs. 70.5, 72.3, 63.8%, respectively, P<0.05). The percentage of blastocysts produced was higher in MI than in MP and MO (21.1 vs. 16.1 and 16.9%, P<0.05) and similar to P (18.4%; P>0.05). Sex ratio and embryo survival after vitrification were similar among groups (P>0.05). Semen selected by Isolate and Optiprep gradient, at the concentrations and small volumes used, demonstrated similar characteristics and in vitro embryo production to conventional Percoll^® gradient.

Valpotić, H., šperanda, M., Kovšca-Janjatovic, A., đidara, M., Lackovic, G., Božic, F., Habrun, B., Srecec, S., Mataušic-Pišl, M. and Valpotic, I. 2014. Levamisole stimulates proliferation of circulating and intestinal immune cell subsets, gut health and performance in weaned pigs. Can. J. Anim. Sci. 94: 43-53. With the growing knowledge of the porcine immune system and its endogenous modulation, it has been clearly stated that exogenous modulation through the use of substances able to modulate immune functions represents an important prophylactic/therapeutic approach in prevention/treatment of both stress- and F4 and F18 enterotoxigenic E. coli (ETEC)-induced infections accompanied weaning. The aim of this study was to evaluate the effectiveness of levamisole (LEVA; 2.5 mg kg^-1 BW in 10 mL) applied per os to weaned pigs in proliferation of circulating and intestinal immune cell subsets throughout a period of 5 wk. Changes in proportion or number of peripheral blood and ileal mucosal leukocytes tested were studied either weekly by flow cytometry or at the end of the experiment (day 35) by immunohistology/histomorphometry, respectively. Pigs treated with LEVA had increased proportions of peripheral blood CD45 lymphoid cells, CD4 and CD8 T cells, and CD21 B cells (P<0.01) between days 14 and 35 following the treatment. Also, LEVA stimulated the proliferation of CD45RA naïve lymphoid cells in interfollicular (P<0.001) and follicular areas (P<0.05) of ileal Peyer's patches at day 35 of the experiment. These pigs had a significantly higher (P<0.05) average body weight (19.7 vs. 17.1 kg) and weight gain at the end of experiment compared with the control pigs (for 15%). We conclude that LEVA stimulated the proliferation of circulating and intestinal lymphoid cell subsets tested and improved performance in weaned pigs, and thus, the drug may nonspecifically enhance their immunity/resistance to F4 and F18 ETEC strains.

López-Campos, Ó., Aalhus, J. L., Galbraith, J., Larsen, I. L., Juárez, M., Uttaro, B. and Robertson, W. M. 2014. The relation of carcass physiological maturity to meat quality in the Canadian Bison Grading System. Can. J. Anim. Sci. 94: 55-62. A total of 119 bull (n=62) and heifer (n=57) bison carcasses were selected to determine the effectiveness of youthful to intermediate physiological maturity [ossification at the 9th/10th/11th thoracic spinous processes (≤50%; 51-65%; 66-80%)] range to accurately classify bison carcasses with respect to quality. Carcasses were classified into three maturity groups according to ossification at the 9th/10th/11th thoracic spinous processes (=50%; 51-65%; 66-80%). Carcass, meat quality and sensory evaluation data were then collected. Bull carcasses were significantly (P<0.0001) heavier than heifers (308.0 vs. 228.6 kg), while heifers had higher (P<0.0001) marbling scores than bulls (368 vs. 289). For both genders, ossification group had little or no impact (P>0.05) on any of the meat quality traits. Gender had an impact on the shear force values for both fresh (P<0.0001) and frozen/thawed (P=0.0002) samples, with bulls having higher values than heifers. Panellists detected differences between heifers and bulls in initial tenderness (P<0.0001; 7.11 vs. 6.27), flavour intensity (P=0.005; 5.40 vs. 5.14), amount of connective tissue (P=0.0002; 7.64 vs. 7.18), and overall tenderness (P=0.003; 7.13 vs. 6.50). Only initial juiciness was significantly affected (P=0.02) by the ossification group (5.38, 5.64 and 5.76). A gender×ossification group interaction was also detected for flavour intensity (P=0.004) and off-flavour intensity (P=0.03), but the magnitudes of the differences were in the order of one-half panel unit or less, generally below the detection of most consumers. The range of physiological maturity studied had limited effects on meat quality and support the elimination of an intermediate physiological maturity grade (51-80% ossification) from the Canadian Bison Grading System.

Avilés, C., Juárez, M., Larsen, I. L., Rodas-González, A. and Aalhus, J. L. 2014. Effect of multiple vacuum packs on colour development and stability in beef steaks. Can. J. Anim. Sci. 94: 63-69. The aim of this study was to compare the colour stability of steaks from longissimus dorsi muscle previously submitted to four treatments of vacuum packaging and aged for 15 d. Muscle portions were either vacuum packed and aged for 15 d (NRP), or repacked after 2 h (RP2h), 8 d (RP8d) and after 2 h and 8 d (RP2h 8d). Purge loss values from RP8d and RP2h 8d treatments were higher (P=0.019) than those from NRP and drip loss was higher (P=0.001) for RP2h and RP8d. Colour changes during a 30-min period of exposure to atmospheric oxygen immediately after opening the packages were similar for repackaged-aged steaks and NRP steaks (P>0.05). Nevertheless, colour stability during subsequent retail display under atmospheric air conditions was affected by the packaging treatment. The decrease in chroma values (P=0.043) and the increase in hue (P=0.011) between day 3 and day 6 was minimum for RP2h 8d, compared with NRP, RP2h and RP8d. Also, the proportion of pigment in the myoglobin form in these three treatments dramatically increased from day 3 to day 6, while no effect was observed for RP2h 8d (P=0.005). Similarly, the decrease over time in the proportion of pigment in the oxymyoglobin form in meat from the RP2h 8d treatment was much lower (P=0.002) than for the other three packaging treatments. Changes in colour stability associated with multiple vacuum packagings may confound results in experimental designs. Thus, if beef colour is to be evaluated, repeated vacuum packaging should be limited.

Scheeren, M. B., Gonyou, H. W., Brown, J., Weschenfelder, A. V. and Faucitano, L. 2014. Effects of transport time and location within truck on skin bruises and meat quality of market weight pigs in two seasons. Can. J. Anim. Sci. 94: 71-78. The effects of season (winter vs. summer), transport time (T: 6, 12 and 18 h) and truck compartment (C) on skin bruise score and meat quality were evaluated in 384 pigs distributed across the top front (C1), top back (C4), middle front (C5) and bottom rear (C10) compartments. Bruise score was higher (P=0.01) in winter than in summer. A T×C interaction was found for pH_u value in the longissimus thoracis (LT) muscle and for drip loss in the LT and semimembranosus (SM) muscles, with higher (P<0.001) pH_u being recorded in the LT muscle and lower drip loss in the LT and SM muscles (P<0.001 and P=0.01, respectively) of pigs located in C10 following 18 h of transport. In summer, higher (P=0.03) pH_u values were found in the LT muscle of pigs transported in C4 and lower drip loss in the LT and SM muscles (P=0.04 and P=0.03, respectively) of pigs located in C10. The results of this study suggest that, while skin bruises are only affected by season, the effects of longer transport time and winter temperatures on meat quality can be aggravated by the compartment location.

Faridi, A., Golian, A., Heravi Mousavi, A. and France, J. 2014. Bootstrapped neural network models for analyzing the responses of broiler chicks to dietary protein and branched chain amino acids. Can. J. Anim. Sci. 94: 79-85. Reliable prediction of avian responses to dietary nutrients is essential for planning, management, and optimization activities in poultry nutrition. In this study, two bootstrapped neural network (BNN) models, each containing 100 separated neural networks (SNN), were developed for predicting average daily gain (ADG) and feed efficiency (FE) of broiler chicks in response to intake of protein and branched chain amino acids (BCAA) in the starter period. Using a re-sampling method, 100 different batches of data were generated for both the ADG and FE sets. Starting with 270 data lines extracted from eight studies in the literature, SNN models were trained, tested, and validated with 136, 67, and 67 data lines, respectively. All 200 SNN models developed, along with their respective BNN ones, were subjected to optimization (to find the optimum dietary protein and BCAA levels that maximize ADG and FE). Statistical analysis indicated that based on R², the BNN models were more accurate in 76 and 56 cases (out of 100) compared with the SNN models developed for ADG and FE, respectively. Optimization of the BNN models showed protein, isoleucine, leucine, and valine requirements for maximum ADG were 231.80, 9.05, 14.03 and 10.90 g kg^-1 of diet, respectively. Also, maximum FE was obtained when the diet contained 232.30, 9.07, 14.50, and 11.04 g kg^-1 of protein, isoleucine, leucine, and valine, respectively. The results of this study suggest that in meta-analytic modelling, bootstrap re-sampling algorithms should be used to better analyze available data and thereby take full advantage of them. This issue is of importance in the animal sciences as producing reliable data is both expensive and time-consuming.

Bergeron, N., Robert, C. and Guay, F. 2014. Antioxidant status and inflammatory response in weanling piglets fed diets supplemented with arginine and zinc. Can. J. Anim. Sci. 94: 87-97. Dietary supplementation with zinc oxide (Zn oxide) and arginine (Arg) is known to improve growth in weanling piglets. The mechanism of action is not yet well understood, although antioxidant effects and inflammatory responses may be involved. This experiment was conducted to evaluate the effects of Zn and Arg supplementation on the antioxidant status and inflammatory response of piglets. Thirty-two 20-d-old weanling piglets were placed for 12 d on diets supplemented or not with Zn (2500 mg Zn oxide kg^-1) and Arg (1%), designated ZN0ARG0, ZN2500ARG0, ZN0ARG1 and ZN2500ARG1. On day 12, blood samples were taken before and 3 h after intra-peritoneal injection of lipopolysaccharide (LPS; 10 µg kg^-1). The piglets were euthanized just after the second blood sample, and samples of mucosae were taken from the jejunum and ileum for determination of mRNA expression and morphological observation. Zn supplementation decreased plasma malondialdehyde measured before LPS injection (P<0.05). Arg supplementation increased the ferric-reducing ability of plasma (indicator of antioxidant status) measured after LPS injection (P<0.05). Piglets fed Zn-supplemented diets had lower total plasma superoxide-dismutase (SOD) activity (P<0.05) but higher plasma tumour necrosis factor-α (P<0.05) after LPS injection. Zinc-supplemented diets increased metallothionein-1 expression and total antioxidant capacity in the ileum and jejunum (P<0.05) and decreased interleukin-10 expression (P<0.05) in the ileum. In the jejunum, the combination of Zn and Arg supplementation increased villus height (Arg×Zn, P<0.05). These results indicate that Zn may reduce systemic oxidation and improve the antioxidant status in the jejunal and ileal mucosae. However, Zn and Arg supplementation did not appear to act synergistically to enhance antioxidant status or reduce inflammation in weanling piglets.

Michalik, B., Biel, W., Lubowicki, R. and Jacyno, E. 2014. Chemical composition and biological value of proteins of the yeast Yarrowia lipolytica growing on industrial glycerol. Can. J. Anim. Sci. 94: 99-104. The aim of this study was to evaluate the chemical composition and biological value of proteins from the yeast, Yarrowia lipolytica, after cultivation on glycerol, a waste product obtained in the production of biofuel from rapeseed. In the tested material we determined moisture, crude protein, ether extract, nitrogen-free extract (NFE), ash, calcium, phosphorus, cadmium, mercury, arsenic, amino acids and fatty acids. The biological value of Y. lipolytica and Saccharomyces cerevisiae proteins was determined with laboratory rats by two methods: the growth method (protein efficiency ratio standardized for casein, PER_stand; net protein retention, NPR) and the Thomas-Mitchell method (biological value, BV; true digestibility, TD). The protein content of Y. lipolytica [467 g kg^-1 dry matter (DM)] was similar to that of S. cerevisiae (479 g kg^-1 DM). Of particular interest was the almost 30-times higher crude fat content in Y. lipolytica (200 g kg^-1 DM) than in S. cerevisiae (6.7 g kg^-1 DM). Yarrowica lipolytica cells accumulated substantial amount of fat in which more than 90% of fatty acids were unsaturated fatty acids with a considerable share of polyunsaturated fatty acids (34%). The low share of sulfur amino acid of Y. lipolytica (2.05 g 16g^-1 N) and S. cerevisiae (2.32 g 16g^-1 N) limited the nutritional value of the protein of the studied yeast. The biological value of proteins as assessed by the growth method (PER, NPR) did not differ between the two yeast species. Finally, Y. lipolytica was a rich source of highly digestible ether extract (over 57%).

Duarte, C. R. A., Eyng, C., Murakami, A. E. and Santos, T. C. 2014. Intestinal morphology and activity of digestive enzymes in broilers fed crude propolis. Can. J. Anim. Sci. 94: 105-114. Propolis is a resin produced by bees that has been investigated for its potential to increase the performance of broiler chickens. Therefore, this study aimed to evaluate the inclusion of crude propolis in the diets of broiler chickens from 1 to 21 d of age. A total of 1020 male chicks were distributed in a completely randomized experimental design into six treatments (0, 100, 200, 300, 400 and 500 ppm of crude propolis), with five replications, and 34 birds per experimental unit. The experimental diets were provided from 1 to 21 d of age and subsequently (from 22 to 42 d of age) the birds were fed a nutritionally complete ration based on corn and soybean meal. All supplemented groups showed similar growth performance in all growth phases (P>0.05); however, there was a linear increase in carcass yield at 42 d of age according to increase in crude propolis inclusion from 1 to 21 d of age (P<0.05). At 7 d of age, relative weight of the gizzard increased linearly (P<0.05) with increasing propolis, and at 21 d of age, relative weight of the large intestine showed a quadratic (P<0.05) response, with the lowest value predicted to occur at 278 ppm of crude propolis. The ileum crypt depth at 21 d of age was affected by propolis, with a quadratic response (P<0.05) and highest value estimated at 323 ppm. At 21 d of age, sucrase activity in the jejunum increased linearly with increasing propolis and maltase activity in the ileum showed a quadratic (P<0.05) response, which predicted highest activity at 292 ppm. Amylase activity was lower in animals supplemented with 100 and 400 ppm of propolis at 21 d of age (P<0.05) compared with the control group. Thus, the crude propolis supplementation is not recommended in broiler diets from 1 to 21 d old given that it does not influence the performance, despite small changes in intestinal morphophysiology at 21 d of age.

Kahindi, R. K., Htoo, J. K. and Nyachoti, C. M. 2014. Short Communication: Effect of dietary lysine content and sanitation conditions on performance of weaned pigs fed antibiotic-free diets. Can. J. Anim. Sci. 94: 115-118. One hundred and ninety-two piglets (7.2±0.50 kg body weight) were fed corn-wheat-soybean meal based-diets to determine dietary Lys requirement in a 2×4 factorial setting [two sanitation conditions (SC): clean and unclean, and four dietary lysine contents: 0.94, 1.09, 1.25 and 1.43%]. The average daily gain (ADG) and gain to feed ratio (G:F) linearly increased (P<0.05) with dietary lysine contents, but were lower (P<0.0001) under unclean sanitation conditions from day 0 to 7 but not from day 8 to 21. Overall, dietary lysine contents did not affect average daily feed intake (ADFI), but unclean sanitation conditions reduced (P<0.01) ADFI; however, ADG was increased by both dietary lysine contents and SC? (P<0.001), whereas only dietary lysine contents affected G:F.

Plaizier, J. C., Legesse, G., Ominski, K. H. and Flaten, D. 2014. Whole-farm budgets of phosphorus and potassium on dairy farms in Manitoba. Can. J. Anim. Sci. 94: 119-128. Whole-farm budgets of phosphorus (P) and potassium (K) were determined on 10 dairy farms in Manitoba between October 2010 and October 2011. These budgets were determined as the difference between total exports, including milk, animals, feed, and manure, and total imports, including feed, manure, animals, and inorganic fertilizer, for each farm. Farms differed in their feeding and manure management strategies. Two farms imported all their feed and exported all their manure. Other farms produced some of their feed and spread most of their manure on their farm. Whole-farm P and K budgets varied from -0.42 to 3.35 and from -1.31 to 11.27 g kg^-1 milk sold among farms, respectively. Efficiencies of P and K utilization were calculated as the exports as a percentage of imports. The P efficiency averaged 48%, and ranged from 22.1 to 109% among farms. The K efficiency averaged 37%, and ranged from 10 to 98% among farms. In the fall of 2010 and 2011, 94 and 98%, of fields sampled had soil test P concentrations lower than the concentration above which further accumulation of P would be regulated (60 ppm). Of the farms that spread their own manure, the highest P and K efficiency were on a farm that exported a proportion of the produced forages and did not import any inorganic fertilizer. The lowest P and K efficiencies were on a farm that imported concentrate feeds, bedding straw and most forages, and had the smallest land base per milking cow to spread manure. Variations in P and K efficiencies demonstrate opportunities to enhance these efficiencies.

Friedt, A. D., McAllister, T. A., He, M. L., Penner, G. B. and McKinnon, J. J. 2014. Effects of replacing barley grain with graded levels of wheat bran on rumen fermentation, voluntary intake and nutrient digestion in beef cattle. Can. J. Anim. Sci. 94: 129-137. Abrasion-milled wheat bran (AMWB) is a relatively new by-product from wheat-based ethanol production. Few published studies are available on the nutritional value of this by-product feed for growing cattle. The objective of this trial was to evaluate the effects of replacing rolled barley with AMWB on apparent nutrient digestibility, voluntary intake and rumen fermentation parameters of beef heifers fed a backgrounding diet formulated to 1.50 and 0.91 Mcal kg^-1 dry matter (DM) of NE_m and NE_g, respectively. Five spayed and rumen-cannulated Angus heifers (584±40 kg) were used in a 5×5 Latin square design. The control diet consisted of 36% barley silage, 24% grass hay, 8% supplement and 32% rolled barley grain (DM basis). Dietary treatments replaced barley grain with AMWB at 8, 16, 24 and 32% of the diet DM. Voluntary DM (P=0.30) and organic matter (OM) (P=0.19) intake were not affected by AMWB inclusion level. Mean rumen pH (P=0.68) as well as duration (min) (P=0.68) and area under the pH curve 5.8 (P=0.27) were not affected by AMWB. Other than acetate, which linearly increased (P=0.03) with increasing AMWB, effects on rumen volatile fatty acids or NH3-N levels were minimal. There was a linear decrease (P<0.01) in DM, OM and gross energy digestibility with increasing AMWB, while acid (P=0.01) and neutral (P=0.03) detergent fibre digestibility decreased in a quadratic manner. A similar quadratic trend (P=0.06) for decreased digestible energy content was also noted with increasing levels of AMWB. Crude protein digestibility was not affected (P=0.94) by treatment. These results indicate AMWB will not support similar gains to barley grain in growing diets due to reduced total tract nutrient utilization and lower digestible energy content.

Amat, S., McKinnon, J. J., Penner, G. B., Simko, E. and Hendrick, S. 2014. Evaluation of mineral status in high dietary sulfur exposed or sulfur-induced polioencephalomalacia affected beef cattle. Can. J. Anim. Sci. 94: 139-149. We examined the mineral status in beef heifers fed high S containing diets with differing forage-to-concentrate ratio (F:C), and in S-induced polioencephalomalacia (PEM) affected feedlot steers. A metabolism trial was conducted as a randomized complete block design using a 2×2 factorial treatment arrangement with main effects of dietary S and F:C using 16 ruminally cannulated heifers. The F:C was modified by altering the proportion of barley silage (4 vs. 51% dry matter), whereas, the S content was modified by using differing sources of wheat dried distillers' grains with solubles (WDDGS) to achieve low and high S diets (LS=0.30 vs. HS=0.67%). Minerals including Cu, Co, Fe, Mg, Mn, Mo, Se and Zn were determined from rumen fluid, blood, brain tissue and urine. Urinary mineral excretion was also assed. During the course of the metabolic trial, an outbreak of S-induced PEM in a commercial feedlot was documented and brain minerals of these PEM steers (n=4) were contrasted with the experimental heifers fed HS diet. There were no interactions between dietary S concentration and F:C (P>0.05). Heifers fed HS diet had reduced (P<0.05) mineral intakes (except for Mo), ruminal Co, Fe and Mn, and serum Mg and Fe relative to those fed LS diet. Heifers fed low F:C diet had reduced (P<0.05) Cu, Fe, Mo and Se intakes, greater (P<0.05) ruminal Cu, Fe, Mn and Zn, and reduced (P<0.05) serum Cu and Se, and greater (P<0.05) serum Mg than heifers fed high F:C diet. Brain minerals were not affected (P>0.05) by F:C or dietary S. However, the PEM brains had reduced Cu (P=0.058), Fe (P=0.003) and Mo (P<0.001) relative to normal brains. Dietary S and F:C did alter the mineral status of the heifers, but no deficiencies or PEM were induced.

Oba, M. and Swift, M. L. 2014. Short Communication: Effects of feeding Falcon or Tyto whole plant barley silage on milk production and feed efficiency. Can. J. Anim. Sci. 94: 151-153. Eight lactating dairy cows were fed diets containing either Falcon or Tyto whole-plant barley silage (Hordeum vulgare; WPBS) in a crossover design to study effects on milk production and feed efficiency. The in vitro fibre digestibility (IVFD) of Falcon and Tyto WPBS was 61.6 and 57.2%, respectively. Cows consuming the Falcon WPBS utilized feed more efficiently compared with those consuming the Tyto WPBS (1.44 vs. 1.32 kg milk kg^-1 dry matter intake) although milk yield was not affected. This research demonstrates that IVFD may be an important quality indicator of WPBS when balancing diets for high producing lactating cows.

Jayasundara, S. and Wagner-Riddle, C. 2014. Greenhouse gas emissions intensity of Ontario milk production in 2011 compared with 1991. Can. J. Anim. Sci. 94: 155-173. For identifying opportunities for reducing greenhouse gas (GHG) emissions from milk production in Ontario, this study analyzed GHG intensity of milk [kg CO₂ equivalents kg^-1 fat and protein corrected milk (FPCM)] in 2011 compared with 1991 considering cow and crop productivity improvements and management changes over this period. It also assessed within-province variability in GHG intensity of milk in 2011 using county-level data related to milk production. After allocating whole-farm GHG emissions between milk and meat using an allocation factor calculated according to the International Dairy Federation equation, GHG intensity of Ontario milk was 1.03 kgCO₂eq kg^-1 FPCM in 2011, 22% lower than that in 1991 (1.32 kg CO₂eq kg^-1 FPCM). Greenhouse gas sources directly associated with dairy cattle decreased less (21 and 14% for enteric fermentation and manure management, respectively) than sources associated with feed crop production (30 to 34% for emissions related to N inputs and farm-field work). Proportions of GHG contributed from different life cycle activities did not change, with enteric fermentation contributing 46%, feed crop production 34%, manure management 18% and milking and related activities 2%. Within province, GHG intensity varied from 0.89 to 1.36 kg CO₂eq kg^-1 FPCM, a variation inversely correlated with milk productivity per cow (kg FPCM sold cow^-1 year^-1). The existence of a wide variation is strong indication for potential further reductions in GHG intensity of Ontario milk through the identification of practices associated with high efficiency.