Effect of some management and nutritional factors on the fertility of milking cows under traditional husbandry system in Sudan

摘要

Six farms (A, B, C, D, E and F) of the intensive system type were selected. They were located 50 km south of Khartoum. Nutritional parameters with respect to metabolizable energy intake (MEI)and crude protein (CP) concentration of the diet were investigated. Other managerial practices were also closely examined. Cows that recently calved were monitored throughout the study period (300 days) for days to first progesterone (P(sup 4)) rise and days to conception using radioimmunoassay (RIA) technique and rectal palpation. The above fertility parameters were correlated with either body condition score (BCS) or body weight (Bwt) at calving, 30, 60 and 90 days from calving. Similar correlations were done after pooling all farms together excluding farm E which consisted of the pure exotic breed. Likewise same correlations were done for the cows grouped according to calving during wet and dry summer. Milk yield at 30, 60 and 90 days from calving were also correlated with days to first P(sup 4) rise and days to conception. Regression analysis were carried out for correlations which showed high or moderate relationships. The interval from caving to ovulation or conception varied within and between farms. Farm E showed the shortest (17) days to first P(sup 4) rise while farm C showed the longest days. Likewise farm E showed the shortest (56) days to conception while farm F showed the longest (161) days. However farm F, showed the lowest conception rate and highest percentage of anestrus cows. Best conception rates within 90 days postpartum were observed in farm C followed by farm E, B, A, D and F. Days to conception was negatively correlated (P&lt;0.03, r= -0.64) with body score at calving but positively correlated with body weight at calving Bwt Calv (P&lt; 0.07, r=0.59) and body weight change at 60 (Bwt.60) days from caving (P&lt;0.11, r=0.05). Days to first P(sup 4) rise was negatively correlated (P&lt;0.004, r=0.99) with body score at calving (BCS.Calv), but positively correlated with Bwt.Calv. (P<0.08, r=0.91), body weight change at 30 days from calving (P< 0.13, r=0.86), and body weight change at 60 days from calving (P<0.08, r=0.91). No significant difference (P=0.29) between wet and dry summer for days to ovulation or conception were observed. When comparing means of BCS or Bwt, at calving 30, 60 or 90 days from calving between the different farms, afrm B showed the lowest (P<0.05) BCS.Calv., BCS 30, BCS 60 and bcs 90, while farm E showed the highest (P<0.05) Bwt.Calv., Bwt. 30, Bwt.60 or Bwt.90. (Author) 93 refs. , 12 tabs.