GROWTH PERFORMANCE OF HOLSTEIN-FRIESIAN HEIFER CALVES REARED USING THREE MILK REPLACER FEEDING REGIMES

摘要

The long-term objectives of feeding and management systems for heifers reared as dairy herd replacements must be to maximise herd lifetime productivity while controlling the cost of rearing. Recently there has been renewed interest in the effects of growth performance of replacement heifers on their subsequent milk production and herd life (Bar-Peled, Robinson, Maltz, Taguri, Folman, Bruckental, Voet, Gacitua, and Lehrer, 1997; Sejrsen and Purup, 1997; Van Amburgh, Gallon, Bauman, Everett, Fox, Chase, and Erb, 1998; Carson, Wylie, McEvoy, McCoy, and Dawson, 2000; Carson, Dawson, McCoy, Kilpatrick, and Gordon, 2002). These studies suggest that enhanced rates of growth from 3 months of age through to puberty may be associated with impaired mammary development and subsequent reduction in lactation performance (Sejrsen and Purup, 1997; Van Amburgh et al., 1998; Sejrsen, 2005), although this might not always be the case (Carson et al., 2000; Carson et al., 2002). Alternatively, it might be possible to influence future productivity by exploiting the growth potential of the heifer during the calf rearing period (0 to 12 weeks), before the period of allometric mammary development begins. Initial studies suggest that accelerated growth of suckled calves (receiving whole milk) produces larger heifers that calve at a younger age and tend to yield more milk during first lactation than their bucket-reared contemporaries receiving milk replacer (Bar-Peled et al., 1997). These findings are supported by those of Shamay, Werner, Moallem, Baresh and Bruckental (2005) who compared heifers reared on high intakes of whole milk with heifers fed restricted milk replacer.