EFFECTS OF WARM VERSUS COLD MILK REPLACERS AND OF FREE-CHOICE HAY POSTWEANING ON PERFORMANCE OF ARTIFICIALLY REARED LAMBS

Abstract

In two artificial rearing experiments lambs were fed, ad libitum, either cold (4.4–7 °C) or warm (27–31 °C) milk replacer with 0.10% formalin (37%, wt/wt, formaldehyde) added to the reconstituted milk replacer. From weaning at 21 days of age to 91 days of age all lambs were fed the same high-concentrate diet (corn grain, soybean meal, 8% ground hay plus minerals and vitamins; approx. 17% crude protein, as-fed). In the second experiment half the lambs from each milk replacer treatment were fed alfalfa hay free-choice postweaning in addition to the high-concentrate diet. Equal survival rates and absence of abomasal bloat on both milk replacer treatments showed that the addition of 0.10% formalin allows warm milk replacer to be safely fed ad libitum to lambs. Both intakes and gains were higher for lambs fed warm milk replacer than for cold. In the first experiment apparent compensatory postweaning growth nullified the weight advantage at weaning for lambs fed warm milk replacer, whereas in the second experiment the weight advantage at weaning was not overcome by the apparent compensatory growth. Feeding hay free-choice postweaning (amounted to 12.5% of the overall diet), in addition to the high-concentrate diet, improved lamb gains and slightly increased feed dry matter required per kilogram of gain, as would be expected as a result of the lower energy content of the overall diet. The results indicate that the addition of 0.10% formalin allows warm milk replacer to be safely fed ad libitum to lambs; that performance, including postweaning carryover effects will be equal to, or greater than that achieved with cold milk replacer; and that free-choice hay in addition to a high-concentrate diet postweaning has a beneficial effect on lamb performance. Key words: Lambs, artificial rearing, warm vs. cold milk replacer