REPRODUCTION
Mating is typically polygynous. Maternal groups exist in a large, loosely structured herds year round. During the wet season, adult males (from bachelor groups or solitary) enter the female groups, and mate with, but do not control, the receptive females who are in estrus for 11 to 72 hours. After mating, males are driven off. Male bovids in general display dominance by posture and movement, and few conflicts escalate to levels of serious injury. Bulls determine estrus by sniffing a cow’s urine and genitals. (Lekagul and McNeely, 1988; Ligda, 1999c; Nowak, 1999; Shackleton and Harestad, 2003)
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Mating System
Timing of reproduction in this species is somewhat variable. In some areas, breeding is seasonally dependent, whereas in other areas it is seasonally independent. Where seasonally dependent, breeding often occurs after the rainy season and calves are born the following year near the beginning of the rainy season. Where seasonally independent, calves may be born year round.
The estrus cycle is 21 days. Of female bovids, water buffalo have the longest gestation period: 300 to 340 days. Females usually have one calf, but they may have twins. A female typically produces an average of one calf every two years. Calves are born weighing 35 to 40 kg, and are red to yellow brown. Nursing lasts 6 to 9 months.
Females reach sexual maturity at approximately 1.5 years of age and remain in a maternal group within a larger herd. Males reach sexual maturity at the age of 3 years, at which point they leave the female group and often join bachelor groups. (Lekagul and McNeely, 1988; Ligda, 1999c; Nowak, 1999; Shackleton and Harestad, 2003)