Reproduction of Goat-Selection of buck and doe is important for selective breeding and obtaining maximum efficiency. Buck and doe should have strong, well-developed frame, good conformation and breed characters. Legs should be straight and well placed under the body.
Goats should be healthy and free from external and internal parasites. They should be chosen from good milking strain and should be the progeny of dams having good performance records.
The skin of a good doe should be loose, pliable and free from dryness. The poor condition of flesh is an indication of good milker and vice versa. The udder of a good milch goat should be soft and pliable rather than meaty. The teats should be pointed straight forward.
Study of sexual behaviour in Black Bengal goat revealed that courtship in the form of sniffing urine and flefihmen exhibited in the form of extending the neck and head upwards with lips in curled, nosing, licking the external genitalia of oestrous doe are the most prominent symptoms of potent buck ready for breeding. The average duration of courtship was found to be 1-10 m in most of the cases (Das et al, 1991).
Avoid the kidding during the peak period of summer and winter to avoid stress. Does are to be bred at the interval of 7 – 8 months for maximum productivity. Cull the old unproductive animals at the age of 6 years and above.
Doe lings reach puberty by 6 to 8 months of age and are usually bred at 7 to 10 months of age. At the time of breeding they should weigh about 30 – 40 kg ie 60 % of adult weight. If the doe lings are not at an optimum weight, breeding should be delayed since puberty is more dependent on body size rather than age. However, delaying breeding much after 10 months of age decreases the reproductive performance. Growth rates of replacements should be monitored and their nutrition adjusted accordingly.
For two to three weeks prior to the breeding season does and doe lings should be gaining weight. This is achieved by increasing the amount of energy being fed. Does manage in this manner will have an increased number of ovulations.
Estrus is the period when the doe will receive the buck. Usually, this period will last from a few hours to 2-3 days and is characterized by frequent and insistent “talking”, tail wagging, and pink colour as well as swelling in the external genital region, sometimes with a discharge. In a study of Das et al (1991) regarding sexual behaviour of Black Bengal goat, it was observed that watery mucous discharge from vulva was the most common and prominent symptoms of oestrous doe. A lactating doe will usually drop in her milk production. The period between oestrous is from 17-21 days. To achieve the highest conception rate, it is best to breed the doe on day two of her oestrous period.
The doe should be bred to freshen once each year with a dry period of about two months. The dry period allows the mammary system time to repair and regenerate for the next lactation. The greater her production the more likely that her body has been depleted of the nutrients used in milk secretion and the longer the dry period required to replenish the losses and store adequate reserves for the next lactation. Does which are not given a normal dry period usually produce only 65 to 75 % as much milk in the subsequent lactation as does give a dry period. The gestation period in goats is 148 to 150 days.
- Central Coastal Agricultural Research Institute, Ela, Old Goa, Goa