Influence of Prepartum Feed Intake of Performance of Cows Fed Ad Libitum During Lactation

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Abstract
Eighteen Canadian Holstein cows, paired according to previous postpartum weight, were given a high or tow allow- ance of hay for 6 wk prepartum. The low allowance was estimated maintenance re- quirement for energy, and the high allow- ance was 1.8 times maintenance to allow for pregnancy. Postpartum both groups were fed concentrate ad libitum, in addi- tion to hay, over 40 wk. Cows of both groups lost body weight prepartum but low cows lost more than high cows (45 kg versus 12 kg after allowance for weights and concepta). Cows of both groups continued to lose weight postpartum but high cows lost more than low so that the two groups equated by 10 wk. Over the first 16 wk postpartum low cows ate more concentrate than did high cows and yielded milk with lower fat percent and higher percents of protein and lactose. There was no significant difference in milk yield. By wk 16 production was not different and the pattern from wk 17 to 40 was a 13% decline in total digestible dry matter intake, a 44% decline in milk energy output, and a 15% increase in body weight.
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