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Abstract -1.21- 6. SUMMARY Milk production records for Egyptian buffalo cows raised in Mehallet Moussa farm. Animal Production Research Institute. Ministry of Agriculture. Egypt were collected in the period from 1970 to 1985. Data on 2946 lactation records including 430 buffalo cows (Paternal half-sister) representing 51 sires were used to estimate the genetic and phenotypic variations of some productive and reproductive traits. Measures of production were lactation period (LP) and yield of milk recorded on 90-day (90DY). 180-daY (180DY). 305-day (305DY) and total lactation (TY). Reproductive measures were age at first calving (AFC). birth weight of calf (BW). number of services per conception (NSC). calving to first service interval (CFS). insemination period (IP). days open (DO). gestation length (GL) and calving interval (el>. Estimation of repeatability and heritability for these traits was estimated by mixed model analysis. The results obtained could be summarized as: (1) Productive trAits: Averages of 90DY. l80DY. 305DY. TY and LP were 601. 994. 1352.6. 1552.6 Kg and 281 days respectively. Parity effects were highly significant (P(O.OOl) for all milk yield traits. All productive traits increased with parity order till reaching the peak and declined thereafter. except TY and LP increased linearly as order of lactation advanced. Season of calving affected (P(O.OOl) all productive traits except 90DY. Summer calvers had the highest production of 90DY. 180DY and 305DY. but spring-calvers had the highest TY and LP. Year of calving constituted highly significant (P(O.OOl) source of variation for all productive traits studied. -i26- All milk yield traits decreased curvlinearly as age at calving advanced except TY which decreased linearly. Age at calving was found to have significant (p<O.05 or P<O.OOl) effects on all productive traits. For all lactations. sire of the cow affected significantly (P<O.05 or P<O.OOl) all productive traits studied while for first lactation there was a significant sire effects (P<0.05) for 305DY and LP. However. cow within sire affected significantlY (P<O.OOl) productive traits in all lactations. Repeatability estimates were moderate and ranged from 0.295 to 0.407 for all lactation traits studied. Heritability estimates for all productive traits in the first and across all lactations were low and ranged between 0.006 to 0.109. (II) Reproductive traits: Averages of AFC. BW. NSC. CFS. IP. DO. GL and CI were 38.0 month. 35.0 Kg. 1.4. 165.7 day. 36.9 day. 202.7 day. 313.6 day and 500.3 day. Most reproductive traits decreased linearly as parity advanced (e.g. CFS. IP. NSC and DO). Parity had significant (P<O.OOl) effects on CFS. IP. NSC. DO and CI. Season of calving affected significantly (P<O.05 or p<O.OOl) CFS. DO. GL and CI. Winter and spring calvers had shorter CFS. DO and fewer NSC and longer CI compared to other seasons. Differences between year of calving were highly significant (P<O.OOl) for CFS. IP. NSC. DO and BW. All reproductive traits studied decreased in a curvilinear manner as age of cow advanced and the differences were significant (P(O.OOl) for most traits. Sire of th~ cow did not affect all reproductive traits of first lactation (except CFS) and across all lactations (except ~---_.- - - 12.’- aWl. Differences in all reproductive traits due to effects of cow within sire were significant. Estimates of repeatability were low for CFS. IP. NSC. DO. GL (estimates ranged from 0.01 to 0.05) or moderate for BW and CI (0.32. 0.24. respectively). Estimates of heritability for most reproductive traits were low and ranged between 0.0 to 0.25. -1.21- 6. SUMMARY Milk production records for Egyptian buffalo Mehallet Moussa farm. Animal Production Research cows raised in Institute. Ministry of Agriculture. Egypt were collected in 1970 to 1985. Data on 2946 lactation records the period from including 430 buffalo cows (Paternal half-sister) representing 51 to estimate the genetic and phenotypic variations sires were used of some producti ve and reproductive traits. Measures of production were lactation period (LP) and yield of milk recorded on 90-day (90DY). 180-daY (180DY). 305-day (305DY) and total lactation (TY) Reproductive measures were age at first calving (AFC). birth weight of calf (BW). number of services per conception (NSC). calving to first service interval (CFS). insemination period (IP). days open (DO). gestation length (GL) and calving interval (el>. Estimation of repeatability and heritability for these traits was estimated by mixed model analysis. The results obtained could be summarized as: (1) Productjve trAits: Averages of 90DY. 180DY. 305DY. TY and LP were 601. 994. 1352.6. 1552.6 Kg and 281 days respectively. Parity effects were highly significant (P (0.001) for all milk yield traits. All producti ve traits increased with parity order till reaching the peak and declined thereafter. except TY and LP increased linearly as order of lactation advanced. Season of calving affected (P (0.001) all productive traits except 90DY. Summer calvers had the highest production of 90DY. 180DY and 305DY. but spring-calvers had the highest TY and LP. Year of calving constituted highly significant (P (0.001) source of variation for all productive traits studied. -i26- All milk yield trai ts decreased curvlinearly as age at calving advanced except TY which found to have significant decreased linearly. Age at (p<0.05 or P<O.OOl) effects calving was on all producti ve traits. For all lactations. sire of the cow productive affected significantly (P<0.05 or P<O.OOl) all trai ts studied while for first lactation there was a significant sire effects (P<O.05) for 305DY and (P<O.OOl) LP. However. cow within sire affected significantlY productive traits in all lactations. Repeatability from 0.295 to 0.407 for all estimates for all producall lactations were low and estimates were moderate and ranged studied. Heritability the first and across lactation traits tive traits in ranged between 0.006 to 0.109. (II) Re~roductive traits: Averages of AFC. BW. NSC. CFS. IP. DO. GL and CI were 38.0 month. 35.0 Kg. 1.4.165.7 day. 36.9 day. 202.7 day. 313.6 day and 500.3 day. Most reproductive traits decreased linearly as parity advanced (e.g. CFS. IP. NSC and DO). Parity had significant (P<O.001) effects on CFS. IP. NSC. DOand CI. Season of calving affected significantly (P<O.05 or p<O.001) CFS. DO. GL and CI. Winter and spring cal vers had shorter CFS. DOand fewer NSC and longer CI compared to other seasons. Differences between year of calving were highly significant (P<O.001) for CFS. IP. NSC. DO and BW. All reproductive traits studied decreased in a curvilinear manner as age of cow advanced and the differences were significant (P (0.001) for most traits. Sire of th~ cow did not affect all reproductive traits of first lactation (except CFS) and across all lactations (except - 12.’- aWl. Differences in all reproductive traits due to effects of cow within sire were significant. Estimates of repeatability were low for CFS. IP. NSC. DO. GL (estimates ranged from 0.01 to 0.05) or moderate for BW and CI (0.32. 0.24 . respectively) Estimates of heritability for most reproductive traits were low and ranged between 0.0 to 0.25. |