Influence of flushing and season of kidding on reproductive characteristics
ارسال کننده : جناب آقای مهدی بوربورمرادی
سطح فعالیت : مدیر ارشد
ایمیل : mahdibourbourmoradi[@]gmail.com
تاریخ ارسال : ۲۴ مهر ۱۳۹۴
دفعات بازدید : 547
زبان نوشتاری : انگلیسی
تعداد صفحه : 8
فرمت فایل : pdf
حجم فایل : 119 KB
A study was carried out to assess the effects of nutritional supplementation (flushing) and season of kidding on reproductive performance of Small East African (SEA) does and growth performance of their crossbred (Norwegian x SEA). Seasons of kidding were defined as season 1 (June- August) and 2 (September to November) which represented the early and late dry months of the year, respectively. A total of 90 grazing does were divided into three groups of 30 does each and monitored for two years. In each observational year, one group (control goats) received no concentrate supplementation while the remaining groups were subjected to 200 or 400 g of concentrate diet/doe/day for a period of 60 days (November to January) before mating. Does were then exposed to sexually active bucks from January through June in 2008 and 2009. Nutritional flushing and season of kidding had no effects (P>0.05) on fertility, prolificacy and fecundity. Nonetheless, the relative weight increase during gestation was 35.8 % in season 1 being higher (P<0.01) than 12.6% recorded in season 2. The proportion of weight loss of does kidding in season 1(6.1%) was, however, lower (P<0.05) than 8.9% in season 2. Kids born in season 1 grew at a faster rate than their counterparts born in season 2 (80 vs. 57 g/day, P<0.05). Consequently, the average weight of kids weaned per doe kidding was 2 kg in favour of season 1. It is concluded that nutritional flushing during peak-dry season may not be necessary for goats to conceive especially when raised on lightly grazed rangeland and that breeding activities of goats should preferably be restricted to January to March for kidding to take place during early dry season (June to August).
MATERIALS AND METHODS
Animals, treatments and management
Effects of sex, type of birth and parity of dam on growth rates of kids
Effects of season of kidding, type of birth and parity stage on live weight changes of does from birth to weaning
The seasonality in feed availability and quality is an important constraint to biological productivity of small ruminants in the tropics (Berhane and Eik, 2006; Ben Salem and Smith, 2008). In Tanzania, as in most tropical countries, small ruminants breed throughout the year and this can result in overall poor survival of dams and kids, reduced reproductive and productive performances especially when late pregnancy and resulting kidding fall into periods with insufficient forage availability (Karikari and Blasu, 2009). However, tropical breeds of goats are known to be a seasonally polyoestrus and therefore it is possible to manipulate their breeding activity to coincide with periods of adequate feed supply and low disease challenges (Amoah et al., 1996).Such a breeding strategy is potentially advantageous both in terms of improved reproductive activity of the does and the growth performance of kids.