Effects of restricted suckling versus artificial rearing on milk production, calf performance and reproductive efficiency of dual purpose Mpwapwa cattle in a semi-arid climate

Abstract

Twenty purebred Mpwapwa and 16 crossbred Mpwapwa cows with calves were used in an experiment to compare restricted suckling (RS) versus artificial rearing (AR) of calves in Tanzania. A randomized design was used. Calves remained with their dams during the first five days and were then allocated to the RS or AR treatments; AR calves were weaned at 75 days of age and were provided with 4 1itres of milk daily for 70 days, while RS calves stimulated milk letdown of the cow and after milking were suckled by their dams for 30 minutes. All calves were grazed and were provided with concentrate, minerals and water ad libitum. Milk yield from cows and milk consumed by calves were recorded for 175 days after calving. Reproductive behavior of the cows was determined by Radio-immuno-assay (RIA) of milk progesterone. Six of the 18 AR cows were affected by mastitis compared to only one of the RS group. Mean (±SE) daily yields of milk for Mpwapwa cows in RS and AR were 6.9 ± 0.45 litres and 7.6 ± 0.41itres (P>0.05), respectively. Corresponding values for crossbreeds were 8.6 ± 0.54 and 8.0 ± 0.59 1itres (P>0.05), respectively. The daily saleable milk for Mpwapwa cows in RS and AR was 6.9 ± 0.45 1itres and 6.0 ± 0.411 (P<0.05), respectively; while for crossbred cows the amounts were 8.6 ± 0.54 1itres and 6.4 ± 0.59 1itres (P<0.05), respectively. Mean daily total milk yields for Mpwapwa RS and AR cows were 8.9 ± 0.44 1itres and 7.6 ± 0.40 1itres (P<0.05) and for crossbreeds 10.6 ± 0.53 1itres and 8.0 ± 0.58 1itres (P<0.05), respectively. Means (±SE) for fat content in bucket milk and residual milk, for Mpwapwa were 3.56 ± 0.25% and 4.97 ± 0.25% (P<0.05), respectively; and for crossbreeds 3.6 ± 0.31% and 6.3 ± 0.31% (P<0.05), respectively. Mean daily gains for RS and AR calves were 381 ± 16 g and 356 ± 16 g (P>0.05), respectively. Saleable milk from RS cows was 15.0% higher for the Mpwapwa and 34.3% higher for the crossbred cows compared to saleable milk from cows of either breed with calves under AR. Body weight of cows postpartum was not affected by restricted suckling. Milk progesterone measurements showed that there was no significant between the RS and AR treatments for the interval from calving to initiation of oestrous (progesterone>0.5nmol/litre). However, RS cows took significantly longer to show a regular oestrous cycle (P<0.05).