Observations on the occurrence of oestrus in Africander and Jersey cattle under extensive conditions in the Northern Cape
Data concerning the occurrence of oestrus in Africander and Jersey cattle under extensive conditions were obtained from a crossbreeding program at Vaalharts Agricultural Research Station. Observations were made during the annual two and a half month breeding season on a herd of approximately 270 Africander and 75 Jersey cattle for five consecutive years. During this period oestrus was observed in 80,3 % of 1297 Africander and in 94,7% of 357 Jersey cows. The occurrence of a relatively long post partum anoestrous period was evident in lactating Africander cows, especially those with the first calf at foot. Only 55,9 % of the latter exhibited oestrus during the breeding season compared to 86,2 % of their Jersey counterparts. The Jersey herd, however, received an energy lick during critical nutritional periods which may have had some effects. Amongst the Africanders, 60,3 % of the observed oestrous periods were first noted during the early morning and 39,7 % in the late afternoon. The corresponding percentages for the Jersey females were 59,0 and 41,0 % respectively. Of the 543 completed oestrous cycles recorded in the Africander herd, 57,1 % were within the normal acceptable limits (18-23 days) as against 53,6 % of the 194 completed cycles of the Jerseys. A cycle length of less than 18 days was recorded in 22,1 and 32,5% of the observations amongst the Africanders and Jerseys respectively. The average length of normal oestrous cycles was 20,53 days in the Africander against 20,35 days in the Jersey.