Evaluation of two methods of estrus synchronization of cattle in Chad —The results of an artificial insemination experiment carried out in the suburban area of N’Djamena are here reported. Two methods of synchronization (Norgestomet combination/estradiol/PGF2a/PMSG and PGF2a only) were used with Chadian zebu and crossed breeds in 2007 and 2008. Females were inseminated after induction of estrus with semen of French Normand breed. The fertility rate was low with PGF2a (29.41%). The results obtained with the combination of several hormones were better (66.66%). The survival rates of crossbreeds were particularly low, 40% in 2007 and 33.33% in 2008, mainly due to the traditional management of the herd and the lack of technical support. The insemination cost of a cow was 39,550 F CFA in 2007 with PGF2a and 59,200 F CFA in 2008 with the method consisting of combining of four hormones. The cost of producing a calf in those two years was very high, 134,470 F CFA in 2007 and 118,400 F CFA in 2008.
Effects of protein and mineral supplementation on the performance of lactating dairy cows gobra and crossbreed guzerat during the dry season in senegal —The purpose of this study carried out in the township of Dahra was to access the effect of dry season protein and mineral supplementation of Gobra and Crossbreed Guzerat cows on milk production. The experimental design is a completely randomized block. The treatments were: supplement of molasse-urea blocks with supplement of hay; supplement of molasse-urea blocks without any hay; no supplement of molasse-urea blocks and supplement of hay; no supplement of molasse-urea block without any hay. For each breed, the treatments were replicated three times on a lot of cows with the similar zootechnic parameters. A total of twelve lactating cows per breed were then used. The supplement of block + hay has significantly (p < 5%) allowed obtaining the largest average daily quantity of milk: 1.9 ± 0.7L/day/cow and 2.4 ± 0.8 L/day/cow respectively in Gobra and CrossbreedGobra*Guzerat. The increases in production compared to the control treatment (without supplement) are 52.63% and 100% respectively in the breed Gobra and Gobra*Guzerat. The supplement of hay comes in the second place and contributes to an additional production of 66.66% in both breeds of cow. Then, the supplement of block follows and it allows increasing the production of 44.44% and 50% respectively in Gobra and Crossbreed. In both races, the supplement of block + hay has allowed obtaining the highest profits of $1.6/L/day/cow for Gobra and $ 2.8/L/day/cow for the Crossbreed, that equals to an increase by $ 0.3 and $ 0.9 compared to the control treatment. The supplement of hay and the block supplement have respectively given a profit of 0.4 and $ 0.3/L/day/cow in Gobra and 0.6 and $ 0.4/L/day/cow in the Crossbreed. The adoption of supplementation molasse-urea block + hay by producers appears an alternative to boost milk production in dry season.