Changes in milk production, fertility and calf mortality associated with retained placentae or the birth of twins
Kay, R.M.
Veterinary Record 102(22): 477-479
1978
ISSN/ISBN: 0042-4900 PMID: 685091 Document Number: 126444
Records of calvings during a 10-yr period at a research institute farm were examined. The av. milk yield for 35 lactations concurrent with twin pregnancies was 4847.1 kg v 4499.7 for 145 lactations following the birth of single calves (P<0.01). The difference between lactations following twin (4695.2 kg) and single births was not significant. The duration of lactations concurrent with twin pregnancies averaged 289.3 days v 294.3 for those following twin and 286.2 for those following single births. For the last 2 groups resp., service period averaged 128.4 and 113.0 days, and number of services/conception 1.66 and 1.59. The percentage of calvings in which calves died was significantly greater for twin (20) than for single calvings (5.5). For 70 cows having a twin birth and 12 having a twin birth + retained placenta, the percentage conceiving satisfactorily in the next reproductive cycle was 68.6 and 66.7 resp.