Interactions of Breeding Systems and Productive Status of Females with the Month and Year of Breeding and their Effects on Conception Rate and Services per Conception in Holstein Cows | ||
| Al-Anbar Journal of Veterinary Sciences | ||
| Article 1, Volume 2, Issue 2, December 2009, Pages 106-115 | ||
| Authors | ||
| S. S. Khalaf; N. N. AL-Anbari | ||
| Abstract | ||
| Breeding records totaling 68844 inseminations at AL-Nasir dairy farm (50 Km South-East of Baghdad) were analyzed to study the interactions between breeding systems and productive status of females with the month and year of breeding and their effects on conception rate (CR) and services per conception (SPC). Data were collected for 10 years from January 1, 1997 to December 31, 2006. Total number of services for lactating (M), dry (D) and virgin heifers (H) and overall means of CR and SPC were 52236, 4503, 12105, 41.65% and 2.61 respectively. In general, CR were not affected significantly (P < 0.01) by the interactions of the month x breeding system except for the month of November and December which differed significantly (P < 0.01) than artificial insemination (AI) of June and September and both AI and natural service (NS) for August. Highest values of CR for AI and NS were in December and November and lowest values were in August, but CR of AI in August (14.85%) differed significantly (P < 0.01) than CR of NS (34.25%) in the same month which indicate a choice of breeding for the hot months of the year. Interactions of productive status of female x month of the year showed that hot months had pronounced effects on CR of M cows but lesser and no effects on CR of D and H respectively. Calculated average CR of hot months (June to September) for M, D, and H were 21.09%, 30.17%, and 56.38%, respectively. Interactions of breeding system x year of breeding revealed overall improvements of CR with successive years for both AI and NS. However, this appeared to be related to improvements in CR of M and D but not in CR of H due to increasing rate of culling of multiparous females. Interactions of breeding system x year of breeding and their effects on SPC indicated general improvements with successive years for both AI and NS. Additionally, interactions of productive status x year of breeding also showed improvement in SPC of M and D but not in SPC of H which again confirm that increasing culling rate of older cows with lower reproductive efficiency led to improvements in SPC with successive years. | ||
| Keywords | ||
| Conception rate; services per conception; heat stress; artificial insemination; natural service; Holstein cows | ||
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