Reduction of milk records per lactation in sheep
2011
Kaštelić, M., Biotechnical Faculty, Domžale (Slovenia). Department of Animal Science | Kompan, D., Biotechnical Faculty, Domžale (Slovenia). Department of Animal Science
Milk recording on sheep in Slovenia was started in the beginning of nineties. It is done in one month interval. Seasonal recording in flock starts when the first animals are weaned twenty-eight days. The recording in flock is continuing to the end of lactation of last animal, approximately nine mounts. The method is accurate but expensive. Lactation yields of milk, fat, proteins and lactose, calculated from reduced number of milk records were compared with officially estimated milk yields. The reductions were: records in first thee (3M), first four (4M), first five (5M) and first six (6M) months of lactation and two reductions on two records in six months. In first case the recording starts within first month after weaning (3U) and in second case in second month after weaning (3P). Yields are mostly overestimated. In some cases are overestimations yields very high. The correlations for milk yield were between 0.883 and 0,915, for fat yield between 0.784 and 0.831, for proteins yield 0.822 and 0.866, and for lactose yield between 0.835 and 0.873. The lowest correlations were found in 3M, then in 3U and 3P followed by 4M, 5M and 6M. The gain from 5M to 6M is not very impressive. I some cases will led simple reduction of milk records per lactation to very incorrect results. Reduced number of milk records demands more sophisticated estimation of milk and milk ingredients yields per lactation.
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