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Animal Reproduction Science 60–61 2000 449–457 www.elsevier.comrlocateranireprosci
Nutritional interactions with reproductive performance in dairy cattle
W.R. Butler
Department of Animal Science, Cornell UniÕersity, 203 Morrison Hall, Ithaca, NY 14853, USA
Abstract
Increased capability for milk production has been associated with a decline in fertility of lactating cows. Nutritional requirements increase rapidly with milk production after calving and
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result in negative energy balance NEBAL . NEBAL delays the time of first ovulation through inhibition of LH pulse frequency and low levels of blood glucose, insulin and insulin-like growth
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factor-I IGF-I that collectively restrain estrogen production by dominant follicles. Up-regulation of LH pulses and peripheral IGF-I in association with the NEBAL nadir facilitates ovulation.
NEBAL reduces serum progesterone concentrations and fertility. Diets high in crude protein support high milk yield, but are also associated with lower reproductive performance. High protein
can result in elevated plasma urea concentrations that affect the uterine environment and fertility. Nutritional interactions resulting in poor fertility of high producing dairy cows include the
antecedent effects of NEBAL and effects of high dietary protein. q 2000 Elsevier Science B.V. All rights reserved.
Keywords: Dairy cattle; Nutrition; Reproduction
1. Introduction
Increased genetic capability for milk production coupled with changes in nutritional management and larger herd size have been associated with a decline in fertility of
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lactating cows Fig. 1; Butler, 1998; Darwash et al., 1999 . Nutritional requirements shift abruptly at parturition as milk production rapidly increases and cows enter negative
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energy balance NEBAL . The severity and duration of NEBAL is primarily related to dry matter intake which, in turn, is related to body condition at calving. NEBAL during
Tel.: q1-607-255-3174; fax: q1-607-255-9829. Ž
. E-mail address: wrb2cornell.edu W.R. Butler .
0378-4320r00r - see front matter q 2000 Elsevier Science B.V. All rights reserved. Ž
. PII: S 0 3 7 8 - 4 3 2 0 0 0 0 0 0 7 6 - 2
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Fig. 1. The inverse relationship between conception rate CR and annual milk production of Holstein dairy Ž
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. cows in New York Butler, 1998, by permission of J. Dairy Sci. 81 1998 2533–2539 .
the first 3–4 weeks postpartum is highly correlated with the days to first ovulation. Because a shorter delay to first ovulation is positively associated with conception rate
later during the breeding period, the length of the postpartum interval to first ovulation represents an important interaction of energy status on reproductive performance.
High milk yield in cows is dependent on high levels of dietary protein as well as energy. Depending upon protein quantity and composition, serum concentrations of
progesterone may be lowered, the uterine environment altered, and fertility decreased Ž
. Butler, 1998 . Since metabolism and utilization of dietary protein depends on energy
availability, the effects of feeding high dietary protein superimposed on the preceding effects of NEBAL represents another important interaction of nutrition on reproductive
performance in dairy cows. A comprehensive review of nutritional effects on ovulation Ž
. and fertility in ruminants is recently available O’Callaghan and Boland, 1999 .
2. Nutrition and first ovulation in lactating dairy cows
