Influence of prepubertal feeding level on milk yield potential of dairy heifers: a review.

Abstract

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.

Effects of two different blends of naturally mycotoxin-contaminated maize meal on growth and metabolic profile in replacement heifers

“…If we also consider the mild (even significant) change in markers of hepatobiliary damage, we may argue that the main factor that could cause a delay of puberty onset was the delayed attainment of an adequate BW. The puberty onset is generally determined by metabolic and endocrine signals related to the nutritional status of the heifer (Sejrsen and Purup, 1997). Among Fusarium mycotoxins, one of the most active in reproductive endocrinology disruption is ZEA but specific controlled studies on dairy heifers are lacking (Fink-Gremmels and Malekinejad, 2007).…”

Influence of age, body weight and body condition score before mating start date on the pubertal rate of maiden Holstein–Friesian heifers and implications for subsequent cow performance and profitability

“…Onset of puberty usually occurs in dairy heifers at 30% to 40% of their expected mature body weight (BW) (Heinrichs, 1993;Van Amburgh et al, 1998). Age and BW are closely interconnected, that is, the negative effect of early calving can be explained by high BW gain before puberty or a too low BW at first calving (Sejrsen and Purup, 1997). Ferrell (1982) reported that age at puberty was not related to body condition score (BCS) of heifers at 452 days of age.…”

Rearing strategy and optimizing first-calving targets in dairy heifers: a review

“…On the contrary, regular injections of GH showed a positive impact on such mammary growth. Inadequate mammary development around puberty alters milk yield potential (Sejrsen and Purup, 1997). Although BW gain before puberty through high-energy diets decreases mammary development when evaluated independently of dietary treatment, heifers that grow faster do not have an impaired mammary development (Silva et al, 2002).…”

“…However, age, BW and frame size are closely interrelated, i.e. the negative effect of early calving can be explained by high BW gain prior to puberty or a too low BW at first calving (Robelin, 1986;Sejrsen and Purup, 1997). From 3 months of age until puberty, mammary gland growth is related to BW, mainly due to an increased deposition of adipose tissue (Troccon, 1996).…”