. 2015. Effects of resting perennial pastures during the sensitive pre-dormancy period in western Manitoba: Pasture productivity and beef cattle performance. Can. J. Anim. Sci. 95: 129Á141. The objective of this experiment was to determine whether avoiding grazing during the sensitive pre-dormancy period (ca. 6 wk prior to a dormancy-inducing frost) would improve forage production, stand quality, alfalfa persistence and animal productivity in perennial pastures. There were two pasture species (PS), alfalfaÁgrass (AG) or grass (G), and three grazing phases. Phase I was conventional rotational grazing of all AG and G sections. In Phase II, one half of AG and G was rotationally grazed (conventional treatment, CT) while the other half was not (rested treatment, RT). Resting AG and G in Phase II required transferring RT animals to swath-graze early-seeded cereals. In Phase III, RT animals that swath-grazed in Phase II were moved to graze the rested sections of the pastures while those that grazed the unrested sections (CT animals) were transferred to swath-graze late-seeded cereals. There was no PS (P 0.05) or rest period (P0.13) effect on total forage yield, carrying capacity, forage disappearance and forage residues. There was no effect (P0.13) of resting on botanical composition or yield in AG. The current study did not observe significant benefits of resting on pasture yield, botanical composition or animal performance.Key words: Resting, alfalfa, grass, persistence, pasture, pre-dormancy, meadow brome Durunna, O. N., Baron, V., Scott, S. L., Robins, C., Khakbazan, M. et Block, H. C. 2015. Les effets du repos des paˆturages permanents pendant la pe´riode sensible de pre´-dormance dans l'ouest du Manitoba : productivite´des paˆturages et performances des bovins de boucherie. Can. J. Anim. Sci. 95: 129Á141. L'objectif de cette expe´rience e´tait de de´terminer si restreindre le broutage pendant la pe´riode sensible de pre´-dormance (c.-a`-d. les 6 semaines avant le gel qui provoque la dormance) peut ame´liorer la production de fourrages, la qualite´du mate´riel sur pied, la persistance de la luzerne et la productivite´animale dans les paˆturages permanents. Il y avait deux espe`ces de paˆturage (PS Á « pasture species »), luzerne-foin (AG Á « alfalfaÁ grass ») ou foin (G Á « grass »), et trois phases de broutage. La phase I e´tait le paˆturage tournant traditionnel de toutes les sections AG et G. Dans la phase II, une moitie´d'AG et de G subissaient le paˆturage tournant traditionnel (traitement conventionnel, CT Á « conventional treatment ») tandis que l'autre moitie´ne l'e´tait pas (traitement repos, RT Á « rested treatment »). Le repos des paˆturages AG et G en phase II ne´cessitait le transfert des animaux RT pour qu'ils fasse paˆturage en andain dans les ce´re´ales seme´es de fac¸on pre´coce. Dans la phase III, les animaux RT qui ont fait paˆturage en andain dans la phase II ont e´te´relocalise´s pour brouter les sections des paˆturages mises au repos, tandis que ceux qui ont brouteĺ es sections sans repos (an...

Khakbazan, M., Carew, R., Scott, S. L., Chiang, P., Block, H. C., Robins, C., Durunna, O. N. and Huang, J. 2014. Economic analysis and stochastic simulation of alternative beef calving and feeding systems in western Canada. Can. J. Anim. Sci. 94: 299–311. Biological and economic data from three field-experimental sites in Manitoba (Brandon Research Centre) and Saskatchewan (Western Beef Development Centre; Semi-Arid Prairie Agriculture Research Centre) were used to determine the economic and financial benefits of alternative beef calving and feeding systems. Stochastic budgets and Monte Carlo simulation techniques were used to evaluate the profitability and risk levels of four alternative livestock beef management systems: early-calving/rapid-gain post-weaning feeding (ER), late-calving/rapid-gain post-weaning feeding (LR), early-calving/slow-gain post-weaning feeding (ES), and late-calving/slow-gain post-weaning feeding (LS). Economic budgets were constructed to evaluate the viability of different phases of beef production including backgrounding, pasture, swath grazing and finishing. Statistical analysis considered operational costs (feed, yardage, implants, medicine, labor, marketing, and other costs), price variables (fed-steer, feeder cattle, and grid pricing premiums/discounts) and steer performance measures such as average daily gain (ADG). Results from the simulation analysis revealed that late-calving systems provided higher returns for livestock producers, while rapid-feeding systems were more preferable for producers who were more risk-averse.

Durunna, O. N., Block, H. C., Iwaasa, A. D., Thompson, L. C., Scott, S. L., Robins, C., Khakbazan, M. and Lardner, H. A. 2014. Impact of calving seasons and feeding systems in western Canada. I. Postweaning growth performance and carcass characteristics of crossbred steers. Can. J. Anim. Sci. 94: 571–582. Crossbred steers (n=272) weaned from early (EC) and late (LC) calving systems (CS) were used to evaluate the impact of two feeding systems (FS) on postweaning performance and carcass characteristics. The steers were randomly assigned to either a rapid-gain feeding (RF) or a slow-gain feeding (SF) system. The RF steers were managed to have body weight (BW) gain of 1 kg d−1 on a silage-hay diet during the backgrounding period prior to finishing, while the SF steers were first backgrounded on a hay diet (gain of 0.7 kg d−1), then grazed alfalfa–meadow bromegrass pasture and annual cereal swaths prior to finishing. All treatment groups received a conventional diet during finishing until the steers attained a target backfat thickness or BW or both. There was no difference (P=0.48) between the two FS for the average age of the steers at the beginning of the experiment. There was a CS×FS effect (P<0.01) on the age at slaughter, where the steers in the EC-RF, EC-SF, LC-RF and LC-SF were 426, 659, 504 and 606 d, respectively. The longer time on feed for LC-RF steers compared with EC-RF suggests the potential effect of summer ambient temperatures at finishing. The EC-RF group had the least carcass fat thickness (P<0.01), but there was no main or interaction effect (P>0.08) on dressing percentage or lean meat yield. There was a FS effect (P<0.05) on meat colour and marbling texture where SF steers had more desirable meat colour and marbling texture. Beef producers adopting EC-RF would finish their calves earlier but at a lighter weight.

. 2015. The effects of spring versus summer calving on beef cattle economic performance in western Canada. Can. J. Anim. Sci. 95: 475Á486. The choice of calving date influences the net revenue of a calving operation as it affects the number of days that calves spend in each feeding phase and when they are subsequently marketed. These two factors determine the costs, revenue, and risk (variance) of each calving system for the calving phase of a beef system. The majority of cowÁcalf producers in western Canada have adopted early calving (EC) in spring due to management factors. However, late calving (LC) in the summer is an alternative beef calving system associated with higher returns due to lower system costs and higher beef prices. It may offer a better match between cow nutritional requirements and pasture availability. The objective of this study was to compare the revenues and risks for a traditional EC system and an alternative LC system at three sites in western Canada. Biological and economic data from three field experimental sites in western Canada (Brandon Research Centre in Manitoba, Western Beef Development Centre in Lanigan, Saskatchewan and Semi-Arid Prairie Agriculture Research Centre in Swift Current, Saskatchewan) were used to determine the costs and benefits of the alternative beef calving system. The results showed that even though the EC has higher cost than the LC, the EC is slightly better than LC in terms of higher net revenue potential, but it comes at a greater risk due to higher revenue variances. The EC system is usually more preferable for risk-neutral producers, whereas the LC system is more preferable for risk-averse producers. Les effets du veˆlage au printemps par rapport au veˆlage a`l'e´te´sur la performance e´conomique des bovins de boucherie dans l'ouest du Canada. Can. J. Anim. Sci. 95: 475Á486. Le choix de la date de veˆlage influence le revenu net d'un e´tablissement de veˆlage puisqu'il a un effet sur le nombre de jours que les veaux passent dans chaque phase d'alimentation ainsi que leur mise en marche´par la suite. Ces deux facteurs de´terminent les couˆts, le revenu et le risque (variance) de chaque syste`me pour la phase de veˆlage chez les bovins de boucherie. La majorite´des producteurs de vaches-veaux de l'ouest du Canada ont adopte´le veˆlage pre´coce (EC Á « early calving ») au printemps pour accommoder des facteurs de gestion. Par contre, le veˆlage tardif (LC Á « late calving ») a`l'e´te´est un syste`me alternatif de veˆlage des bovins associe´s a`des rendements plus e´leve´s imputable aux couˆts plus faibles et une hausse des prix du baeuf. Il pourrait offrir un meilleur accommodement entre les besoins nutritionnels des bovins et la disponibilite´des paˆturages. L'objectif de cette e´tude e´tait de comparer les revenus et les risques des syste`mes traditionnels EC et syste`mes alternatifs LC a`trois sites dans l'ouest du Canada. Les donne´es biologiques et e´conomiques de trois sites d'expe´riences sur le terrain dans l'ouest du Canada (le Centre de Recherche d...

Legesse, G., Small, J. A., Scott, S. L., Kebreab, E., Crow, G. H., Block, H. C., Robins, C. D., Khakbazan, M. and McCaughey, W. P. 2012. Bioperformance evaluation of various summer pasture and winter feeding strategies for cow-calf production. Can. J. Anim. Sci. 92: 89–102. Bioperformance of two summer pasture and four winter feeding cow-calf production strategies in the western Canadian Parkland was evaluated. Diet composition and animal data were collected over 5 production years. Each production year began with fixed-time artificial insemination (TAI) of cows and turnout of cow-calf pairs (n=288 yr−1 including 76 primiparous replacement cows) assigned to either alfalfa-grass (AG, n=9 paddocks) or grass (G, n=9 paddocks) pastures until weaning. Post-weaning, pregnant cows (n=240 yr−1) were assigned to either extended-grazing (EG, n=120) of dormant regrowth of perennial pastures and swathed annual crops, or one of three diets fed in a drylot (DL): hay (HY, n=40), straw/barley (SB, n=40; 70% oat straw:30% steam-rolled barley grain DM), and silage/straw (SS, n=40; 40% barley silage:60% oat straw DM). Common diets were used for all treatment groups between the weaning and winter feeding period, as well as between the pre-calving and summer grazing period. Cow and calf body weight (BW) gains were higher (P<0.05) for AG than G pasture until the third production year and the advantage diminished as the carrying capacity declined. The latter may be attributed to a lack of spring/summer moisture. Further, G pastures required more nitrogen fertilizer to achieve the same level of bioperformance as that of AG pastures in years 4 and 5. Cows in the EG treatment maintained BW better than those in the DL treatment (especially those cows receiving the SS diet) except in year 5 (P<0.05) in which drought resulted in lower body weights for cows in the EG treatment. On all treatments, cows maintained BCS that supported reproductive function; however, fertility to TAI was lowest (P<0.05) in years 4 and 5. Cows in the DL group had a 1.8 times greater risk of being culled before turnout and as a result lower (P<0.05) rates of calf survival to weaning. In conclusion, AG pastures and EG are important alternatives to further develop for cow-calf production in western Canada.