Growth Performance of Holstein-Friesian heifer calves weaned at different ages and raised in mobile calf hutches and conventional calf pens in Botswana

Abstract

This study was designed to evaluate the growth performance of Holstein-Friesian heifer calves weaned at three different ages and reared in two housing types i.e. mobile calf hutches and conventional calf pens at Sebele Agricultural Research Station, Botswana. Forty-eight Holstein- Friesian heifer calves from five dairy farms around Gaborone were weighed and allocated randomly to two calf housing types and three weaning age treatments with 8 heifer calves per treatment. In both housing types heifer calves were weaned at 6, 9 and 12 weeks of age. All heifer calves were given four litres of whole milk twice a day until a week before weaning. A week prior to weaning, calves were fed half quantity of milk once a day. Heifer calves also received calf starter meal, chopped lablab hay and water according to appetite until 22 weeks of age. Feeds and orts were weighed and recorded daily. Heifer calves were weighed every week and performance, as reflected in live-weight changes, was evaluated for type of housing and weaning age. Data was analysed using GLM of SAS R. Heifer calves’ performance was similar across housing type during the pre-weaning period. At 22 weeks of age, heifer calves weaned at 9 weeks of age had a mean weight of 140.5 ± 5.7 which was significantly higher (P<0.05) than mean weight of 128.2 ± 3.5 and 131.0 ± 3.7kg for calves weaned at 6 and 12 weeks of age respectively in both conventional calf pens and mobile calf hutches. Post-weaning average daily gain (ADG) of heifer calves housed in conventional calf pens and weaned at 9 weeks of age were 1.06 ± 0.17 kg compared to those weaned at 6 and 12 weeks of age which were 0.78 ± 0.11 and 0.94± 0.25kg respectively. Post-weaning ADG of heifer calves housed in mobile calf hutches and weaned at 9 weeks of age were 0.98 ± 0.31 kg compared to those weaned at 6 and 12 weeks of age, which were 0.74 ±0.12 and O.84± 0.18kg, respectively. In both housing types calves weaned at 9 weeks were heavier than those weaned at 6 and 12 weeks of age therefore heifer calves can be successfully weaned at 9 weeks of age. Since the performance of heifer calves reared under the two housing systems did not differ significantly (P5O.O5) and the mobile calf hutches were cheaper to construct than conventional calf pens, mobile calf hutches can be an alternative housing system for dairy calves in Botswana.