Efficiency of feed utilization in Holsteins selected for yield.
Feed intakes were obtained for d 71 through d 120 postpartum for 36 first lactation selection and 32 control cows during the last 3 yr of a 16-yr selection experiment for FCM yield in Holsteins. The ration consisted of concentrates fed according to production, limited alfalfa hay, and ad libitum corn silage. The higher estimated net energy intake by selection cows was due primarily to their significantly higher silage intake. Grain intake was slightly higher for the selection animals, but the control animals had a slightly higher hay intake. Neither differences was statistically significant. Only small and statistically nonsignificant differences in BW and weight change were found between the two groups. Selection animals had a 7.6% advantage in gross efficiency for the 50-d trial. Selection for yield gave a desired correlated change in gross feed efficiency.
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JE
Department of Animal Science, North Carolina State University, Raleigh 27695-7621.
D000821:Animal Feed; D000818:Animals; D001947:Breeding; D002417:Cattle / Q000235:genetics / Q000378:metabolism*; D004435:Eating; D002149:Energy Intake; D004734:Energy Metabolism; D005260:Female; D007774:Lactation; D012820:Silage