Influence of prepubertal feeding level on milk yield potential of dairy heifers: a review.
In replacement heifers, high levels of feeding resulting in high growth rates in the prepubertal period can cause severe reduction of the milk production potential. This has been demonstrated in many experiments; however, there are a number of experiments where this effect is not seen. In many cases, the reason for the lack of effect seems fairly obvious (short treatment periods, high pretreatment growth rates, small growth rate differences between treatment groups, variation of growth rates within treatment groups, treatment periods outside the critical period, etc.). However, in a few experiments absence of treatment effect cannot be explained in this way. This demonstrates that our knowledge on the effect of nutrition during rearing on the future milk yield of heifers is incomplete and that it may be possible to develop high growth rate feeding regimens for heifers. Experimental evidence suggests that the observed negative effects of feeding level on subsequent milk are due to impaired mammary development. Development of suitable high growth rate feeding regimens therefore requires understanding of the influence of nutrition on the physiological regulation of mammary development. Available data suggest that the growth hormone-insulin-like growth factor I axis is involved, but it is not clear how. It is likely that understanding of the role of insulin-like growth factor binding proteins is important. Alternative hypotheses involve possible effects of growth factors and modifications of mammary tissue sensitivity to hormones and growth factors.
Sejrsen
K
K
Danish Institute of Animal Science, Foulum, Tjele, Denmark.
Purup
S
S
D000375:Aging / Q000378:metabolism* / Q000502:physiology*; D000818:Animals; D002417:Cattle / Q000378:metabolism* / Q000502:physiology*; D004435:Eating / Q000502:physiology*; D005260:Female; D013006:Growth Hormone / Q000494:pharmacology; D007774:Lactation / Q000502:physiology*; D008321:Mammary Glands, Animal / Q000254:growth & development / Q000502:physiology; D008892:Milk / Q000378:metabolism*; D012741:Sexual Maturation / Q000502:physiology; D013002:Somatomedins / Q000502:physiology
D013002:Somatomedins; D013006:Growth Hormone