Evaluation des performances de reproduction des femelles zébus Gobra et des croisés F1 après insémination artificielle en milieu traditionnel dans la région de Thiès au Sénégal

Assessment of the Reproduction Performance of Gobra Zebu Females and F1 Crossbreeds after Artificial Insemination in Traditional Environment in the region of Thies (Senegal). This study was carried out from October 2007 to March 2009 on 237 Gobra zebus after an insemination campaign in the area of Thies (Senegal) where it aimed at evaluating the performance of Gobra females and their products after artificial insemination. The rate of gestation was 44.3% (n=105) with an average pregnant period of 289±6 days. The rates of birth (total number of cows having calved on total number of inseminated cows), prolificacy (total number of crossbreed born on total number of kidding cows) and abortion (total number of aborted cows during the period of pregnancy on total number of pregnant cows) were respectively 34.6 (n=82), 106, and 21.9% (n=23). The rate of abortion was significantly influenced by the Body Condition Score (BCS) at the day of the diagnosis of gestation (p<0.05) and the age of the cows (p<0.04).The size of the range had a significant effect (p<0.04) over the gestation period. The birth rate was significantly influenced by the BCS at day 60 after insemination. In F1crossbreed (products resulting from the insemination of the Gobra female by either Holstein, or Montbeliard semen), the rates of still birth (number of fetuses still-birth after a normal pregnancy), gemellity (total number of twin births on total number of recorded births) and mortality were 8 (n=7), 6.89 (n=6) and 4.6% (n=4) respectively, with a sex-ratio in favor of the females. The average body weights at birth, three and six months later were 24.5±0.5 kg, 46±1.7 kg, 91.87±2.6 kg respectively, in calves (n=59) raised in stalling parked permanently receiving enclosures of the straw, the crop waste products, industrial concentrated food. They amount to 21.64±1.2 kg, 33.2±4.28 kg, 67.1±16.3 kg, respectively, in calves (n=178) led in extensive breeding with natural pasture during the day with a shepherd and crop waste products (sheets and stems of manioc, corn stems, groundnut hulls) the evening in enclosure when returning in the pasture. The prices of F1crossbreed females at 3 and 6 months after birth were statistically different from those of the males.