Effect of feeding regime, growth intensity and age at first insemination on performances and longevity of Holstein heifers born during autumn

A comparative study of three growth profiles during rearing in dairy heifers: Effect of feeding intensity during two successive winters on performances and longevity

“…With an ADG around 800 g/d before 300 d of life in the present study, puberty probably occurred before the experimental treatments, at least for Holstein heifers (Le Cozler et al, 2009). This 800 g/d value is close to the recommendation for optimal ADG reported by Sejrsen et al (2000) and Zanton and Heinrichs (2005), and it probably explains why no differences in long-term lactation effects were noted between treatments.…”

“…As reported in other experiments (Le Cozler et al, 2009), year of birth significantly (P < 0.05) affected most parameters and was included in the model. The expected differences in ADG due to feeding management during winter (800, 600 and 400 g/d for H, M and L heifers, respectively) were close to those observed during the experiment.…”

“…In the present experiment, heifers fed at an inadequate rate during winter had lower performances during second and later lactations. In another longterm experiment, Le Cozler et al (2009) pointed out the insufficiency of studying effects of a particular feeding strategy only on first-lactation performances. Some factors that are significant during the first lactation can become non-significant in later lactations, and vice-versa.…”

“…The milk yield response function to increasing average daily live weight gain (ADG) is curvilinear: it increases up to the genetic optimum ADG and decreases thereafter with increasing levels of ADG (Hohenboken et al, 1995). Results of inducing compensatory growth around puberty either deliberately (Ford and Park, 2001) or inadvertently (Le Cozler et al, 2009) also showed positive or no effects on milk yield. A seasonal calving system generally is based on grazing optimisation, meaning that feeding strategy is connected closely to seasons.…”

Effect of average daily gain on body size, metabolism, and milk production of Italian Holstein heifers raised on two different planes of nutrition and calving at two different ages

“…An identical observation can be made about milk components production. Recently, Le Cozler et al (2009) reported that the reduction of ADG, during the period from 4 to 12 mo of age, from 890 to 736 g had no significant effect on future milk production.…”