Mechanistic (COWPOLL and MOLLY) and empirical (IPCC Tier 2 and ELLIS) models were used to predict enteric CH4 emissions from 2 summer pasture systems and 4 winter feeding strategies for cow calf ...production in the Western Canadian Parkland. The models used average values for nutrient composition of diets, body weight and body condition score of multi- and primiparous cows to predict 90d emissions for each strategy. Average values were determined from data collected over 5 production years with British-Continental crossbred cows assigned to each strategy for life. Each production year began in June with summer grazing of cow calf pairs (n=288/yr including 76 primiparous cows) assigned to either alfalfa-grass (AG) or grass (G) pastures until weaning in September. November post weaning, pregnant cows (n=240/yr) were assigned to either extended grazing (EG) of dormant regrowth of perennial pastures and swathed annual crops, or one of 3 diets fed in a drylot: hay (HY), straw/barley (SB; 700 oat straw:300 steam-rolled barley grain dry matter (DM)), or silage/straw (SS; 400 barley silage:600 oat straw DM). Cows were fed common diets between weaning and wintering, and pre-calving and grazing of summer pastures. Differences in prediction of enteric CH4 emissions were much bigger among models (26–35%) than among systems (3–5%). For suckled beef cows, the mechanistic and empirical models predicted similar enteric CH4 between AG and G summer pasture groups. The COWPOLL, MOLLY and ELLIS models predicted enteric CH4 emissions from dry pregnant cows to be higher for EG and HY than SB and SS winter feeding strategy groups. In contrast, IPCC Tier 2 predictions were lowest for EG. Enteric CH4 emissions from cow calf production can be lowered in the winter by feeding dry pregnant cows conserved feeds containing straw combined with barley silage or grain, rather than hay alone. A more comprehensive assessment is required to determine the net contribution of extended grazing or drylot feeding programs to greenhouse gas mitigation strategies for beef production. Finally, the substantially higher differences in the prediction of enteric CH4 emissions among models than among production systems preclude their use for regulatory purposes in their current form.
This article is part of the special issue entitled: Greenhouse Gases in Animal Agriculture – Finding a Balance between Food and Emissions, Guest Edited by T.A. McAllister, Section Guest Editors; K.A. Beauchemin, X. Hao, S. McGinn and Editor for Animal Feed Science and Technology, P.H. Robinson.
Khakbazan, M., Durunna, O. N., Sirski, T. K., Brewin, D. G., Huang, J., Berry, N., Iwaasa, A. D., Scott, S. L., Robins, C. D., Block, H. C. and Lardner, H. A. 2015. The effects of spring versus ...summer calving on beef cattle economic performance in western Canada. Can. J. Anim. Sci. 95: 475–486. 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 cow–calf 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.
Durunna, O. N., Baron, V., Scott, S. L., Robins, C., Khakbazan, M. and Block, H. C. 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: 129â141. 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), alfalfaâgrass (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 (P>0.13) effect on total forage yield, carrying capacity, forage disappearance and forage residues. There was no effect (P>0.13) 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.
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: 299â311. 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., Girardin, L. C., Scott, S. L., Robins, C., Block, H. C., Iwaasa, A. D., Khakbazan, M. and Lardner, H. A. 2014. The effects of spring versus summer calving on beef cattle reproductive ...and growth performance in western Canada. Can. J. Anim. Sci. 94: 259â271. The majority of beef producers in western Canada have adopted a spring calving system. Evaluating alternative calving systems such as summer calving may lead to better use of forage resources to optimize cow-calf productivity. In order to evaluate the impact of calving system on cow-calf productivity, 346 Hereford or Angus crossbred cows were used in a 3-yr research study (2007 to 2009) at Brandon, Manitoba; Swift Current, Saskatchewan and Lanigan, Saskatchewan. Cows were bred to calve from February to May (early-calving system, EC) or from May to August (late-calving system, LC). Each system was evaluated for effect on performance and reproductive efficiency. Forage yield, utilization and nutritive value were assessed. Cow body weights (BW), ultrasound measures of backfat and calf BW were evaluated at precalving, breeding and weaning. There was no difference between calving systems for pregnancy rate (P=0.13) EC (93.0%) vs. LC (95.8%); calving rate (P=0.89) EC (92.0%) vs. LC (91.7%) or proportion of calves born alive (P=0.85) EC (99.5%) vs. LC (99.6%). The average length of calving season was not different (P=0.26) between the two systems. The EC cows had greater (P=0.002) BW losses from calving to breeding but greater (P=0.001) BW gain from breeding to weaning than LC cows. Although calves born in LC had greater birth BW (P=0.003) than EC calves, calf weaning rate (P=0.01) and calf weaning BW (P<0.0001) were greater in EC. The higher weaning rate and higher weaning BW with EC has the potential to increase cow-calf productivity and may be more attractive to beef producers in western Canada.
