Estrous cycle and period evaluation in an undefined breed type (SRD) for goats in Northeast Brazil.

An experiment was conducted to evaluate the length and distribution of estrous cycles and periods throughout the year. Thirty SRD female goats, 16-20 months of age were randomly assigned to two treatments (control and feed supplemented) of 16 and 14 animals each. All animals were grazed on native pasture (2.3 ha/head/year) with ad libitum salt and bone meal. The supplemented goats also received green chopped elephant grass at the rate of 2 percent dry matter or their body weight in addition to native pasture during the most critical part of the dry season. The data obtained from these goats were also compared for the wet season and dry season. From the estrous cycles observed 10.6, 76.9 and 12.5 percent were considered as short (less than 15 days), medium (15-24 days) and long (greater than 24 days), respectively. Individual estrous cycle lengths varied from 5-69 days and individual estrous period lengths varied from 12-192 hours. The average lengths of the estrous cycles were 20.9 + 6.9 vs 21.5 + 7.0 days (P greater than 0.05) and of the estrous periods 55.8 vs 57.4 hours (P greater than 0.05) for the control and feed supplemented groups, respectively. The average of the estrous cycles and periods were 20.6 vs 21.8 days (P greater than 0.05) and 62.02 vs 51.17 hours (P greater than 0.05) for the wet and dry seasons, respectively. The occurrence of estrous activity classified by month was evenly distributed throughout the year (average of 8.3 percent and monthly variation of 7.0 - 9.8 percent