Improvement of Beef Cow Biological Efficiency Dan Shike
Improvement of Beef Cow Biological Efficiency Dan Shike, Ph. D University of Illinois Champaign-Urbana
Why all the buzz about efficiency? • Increasing world population • Increased utilization of feed for fuel • Increasing feed cost (including forages) • Other inputs increasing in cost – Fuel, transportation, fertilizer
Profitability • Traditional focus on outputs • Feed costs have historically been 50 -70% of the cost of production in beef enterprises • As corn prices approached and exceeded $7 per bushel, feed costs were nearly 80% of the costs in many feedlot operations in US
Feed Efficiency Feed: Gain < 2: 1 < 3. 5: 1 > 6: 1
Why are beef cattle less efficient? • Maintenance requirements – 50% of total energy expended in beef production is used for maintenance of the cow • High fiber diet – Rumen fermentation – Bacteria produce VFA – Bacteria produce methane
Why haven’t we made any progress? • No selection for feed efficiency • Why? – Requires individual feeding • Expensive facilities • High labor requirement • Lack of social interaction decreases feed intake – Difficulty in defining efficient female
Measures of feed efficiency • Feed conversion ratio (FCR) • Residual feed intake (RFI) • Residual BW gain (RG)
Measures of efficiency • Residual Feed Intake (RFI) – The difference between actual intake and predicted intake based on animal’s gain, maintenance requirements for its body weight, and composition – NEGATIVE RFI IS GOOD! • Required less feed then predicted – Independent of growth and mature size – Linked to biologically relevant traits associated with feed efficiency • Digestibility, heat production, protein turnover
Measures of efficiency • Residual BW Gain (RG) – The difference between actual gain and predicted gain based on animals intake, maintenance requirements for its body weight, and composition – POSITIVE RG IS GOOD! • Gained more weight than predicted – Correlated to growth
Beef cow efficiency • What about cow efficiency? – ~70% of feed resources for cowherd – ~70% of feed for maintenance – 50% OF ALL FEED TO MAINTAIN COWHERD • How do we define cow efficiency? – Pounds of calf weaned per cow exposed unit of feed energy consumed – What about longevity? per
Efficient Cow • Can you tell by looking at them?
Maintenance energy High Maintenance Cow • • • High milk production High visceral organ weight High body lean mass Low body fat mass High output and high input Low Maintenance Cow • • • Low milk production Low visceral organ weight Low body lean mass High body fat mass Low output and low input
Environment Restricted feed resources Abundant feed resources • Favors more moderate size, moderate milk production • “Low maintenance” breeds are most efficient • Favors larger, heavier milking biological types • “High maintenance” breeds are most efficient – Angus, Red Poll • High maintenance breeds are least efficient – Simmental, Charolais, Limousin, Gelbvieh • Low maintenance breeds are least efficient – Hereford, Angus, Red Poll Jenkins and Ferrell, 1994
Cow efficiency research • Funded by American Angus Association – Post-weaning intake evaluation on replacements – All females given opportunity to breed – Evaluate 2 -year-old cows • 60 d postpartum evaluation period – 2 week intake evaluation – BW, body condition score, ultrasound fat, milk production • 240 d postpartum evaluation – 2 week intake evaluation – BW, body condition score, ultrasound fat – Repeat again as 5 -year-old mature cows
Variation in cow efficiency Small Cow Big Cow Moderate Cow BW, lbs 1186 1453 1305 1307 Milk Production, lbs 15. 9 22. 9 17. 9 20. 5 BCS 5. 5 6. 0 5. 5 DMI, lbs 56. 7 45. 4 54. 5 35. 7 Adcock et al. , 2011
Correlations of heifer and 2 year-old cow traits Cow. L DMI Cow. L BW Cow. L Milk Cow. Dry DMI Cow. Dry BW Heifer DMI 0. 45 -0. 21 -0. 17 0. 42 0. 09 Heifer RFI 0. 20 -0. 01 -0. 04 0. 15 0. 02 Heifer RG -0. 11 0. 12 -0. 05 0. 14 Cow. L = Cow traits at 60 d postpartum (lactating) Cow. Dry = Cow traits at 240 d postpartum (dry cow) Correlations in bold are significant at P ≤ 0. 05
Ongoing project • Intake on 486 heifers postweaning • Intake on 274 2 -year-old cows • Intake on 34 5 -year old cows – 2 nd year of 5 -year-old cows this year • Continue to evaluate fertility, productivity, and longevity
National Program for the Genetic Improvement of Feed Efficiency in Beef Cattle
Intake x Diet ► Is there a genetics x diet interaction for intake or RFI? ¡ Feedlot efficiency trials – high-energy, grain-based ¡ Cowherd – moderate to low-energy, forage-based ► Why would they be the same? ¡ Maintenance turnover) ► Why energy (heat production, protein might they be different? ¡ Intake regulation Grain – chemostatic Forage – fill-regulated
Forage vs. Grain ► 162 spring-born, Charolais-sired calves ► 274 fall-born, Charolais-sired calves ► Period 1 (half on forage; half on grain) ¡ 3 week transition / adaptation period ¡ 2 day initial and final weights (70 d test) Ultrasound 12 th rib fat thickness at start and finish Weighed every 2 weeks ► Period ¡ 3 2 evaluation (all cattle on grain) week transition/adaptation period ¡ 2 day initial and final weights (70 d test) Ultrasound 12 th rib fat thickness Weighed every 2 weeks
Diets Forage Grain Ingredient % of diet, DMB Husklage 47. 5 20 Alfalfa haylage 47. 5 High moisture corn Supplement 5 Ground corn 30 Husklage 25 DDGS 15 Supplement 10 NEm = 1. 557 Mcal/kg NEg = 0. 956 Mcal/kg Target 2 lbs/d gain NEm = 2. 004 Mcal/kg NEg = 1. 359 Mcal/kg Target 4 lbs/d gain
Forage – Grain (spring-born) Item Forage DMI Forage ADG Forage RFI Grain DMI Grain ADG Grain RFI 1 0. 69 0. 58 0. 57 -0. 09 0. 26 1 0. 00 0. 51 0. 01 0. 13 1 0. 21 -0. 06 0. 41 1 0. 53 0. 58 1 0. 00 Grain RFI 1 Correlations in bold are significant at P ≤ 0. 05
Forage – Grain (fall-born) Item Forage DMI Forage ADG Forage RFI Grain DMI Grain ADG Grain RFI 1 0. 70 0. 51 0. 62 -0. 29 0. 15 1 0. 00 0. 40 -0. 22 -0. 04 1 0. 28 0. 01 0. 35 1 0. 18 0. 66 1 0. 00 Grain RFI 1 Correlations in bold are significant at P ≤ 0. 05
Summary • Variation in feed intake and efficiency – Opportunity to select for and improve • Best measure / definition of efficiency? – Depends if it is feedlot or cowherd – Depends if it is for selection or research • Need to continue to collect phenotypes – Need INTAKE – Understand relationships of traits – Geneticists will determine best tools for selection
Questions?
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