پردیس کشاورزی و منابع طبیعی دانشگاه تهران Iranian Journal of animal Science 2008-4773 44 1 2013 05 22 Effect of Calf Birth Weight on some of the Economically Important Traits in Iran,s Holstein Dairy Cow Population Effect of Calf Birth Weight on some of the Economically Important Traits in Iran,s Holstein Dairy Cow Population 35 43 32129 10.22059/ijas.2013.32129 FA Seyyed Shadi GHORAISHY Graduate Student, Department of Animal Science, University of Zabol, Zabol, Iran Mohammad ROKOUEI Assistant Professor Department of Animal Science, University of Zabol, Zabol, Iran Mehdi SARGOLZAEI Faculty Member Centre for Genetic Improvement of Livestock, University of Guelph, Guelph, ON, Canada Ahmad MOGHIMI ESFANDABADI Instructor Animal Breeding Center of Iran, Karaj, Iran Journal Article 2012 03 11 Birth Weight (BW) is the first trait recorded fllowing birth. It can influence the performance of thecow and as well impact the performance of the calf it,s duringits maturity. To investigate the effect ofa calf,s BW on the performance of Holstein dairy cattle in Iran, the records gathered between 1967 and2010 were obtained from the Iranian Animal Breeding Center. The data were then used to model theproductive and reproductive traits including Calving to First Insemination (CFI), First Service toConception (FSTC), Calving Interval (CI), and dystocia. BW of calves within each herd were groupedinto five categories based on standard normal distribution (z≤-0.8416, -0.8416 <z≤-0.2533, -0.2533<z≤0.2533, 0.2533<z≤0.8416, <z 0.8416) to survey the effects of BW of each calf on theproduction and reproduction of dams. The results indicated that a calf,s BW significantly (P<0.001)affected the production, CFI, CI, and dystocia in the first three calving periods. The trend of BW of acalf on the productive and reproductive traits found to be respectively positive vs. negative The effectof BW on the incidence of dystocia was higher for the first calving than for the second and third ones.A maximum deviation of least square means of dystocia in the first three calving periods was observedin the fifth weight group. They were recorded as: 0.310, 0.154 and 0.137, accordingly. In conclusion,BW of a calf may be well related to the efficiency of Holstein herds in Iran and which could beconsidered in the breeding and management programs. Birth Weight (BW) is the first trait recorded fllowing birth. It can influence the performance of thecow and as well impact the performance of the calf it,s duringits maturity. To investigate the effect ofa calf,s BW on the performance of Holstein dairy cattle in Iran, the records gathered between 1967 and2010 were obtained from the Iranian Animal Breeding Center. The data were then used to model theproductive and reproductive traits including Calving to First Insemination (CFI), First Service toConception (FSTC), Calving Interval (CI), and dystocia. BW of calves within each herd were groupedinto five categories based on standard normal distribution (z≤-0.8416, -0.8416 <z≤-0.2533, -0.2533<z≤0.2533, 0.2533<z≤0.8416, <z 0.8416) to survey the effects of BW of each calf on theproduction and reproduction of dams. The results indicated that a calf,s BW significantly (P<0.001)affected the production, CFI, CI, and dystocia in the first three calving periods. The trend of BW of acalf on the productive and reproductive traits found to be respectively positive vs. negative The effectof BW on the incidence of dystocia was higher for the first calving than for the second and third ones.A maximum deviation of least square means of dystocia in the first three calving periods was observedin the fifth weight group. They were recorded as: 0.310, 0.154 and 0.137, accordingly. In conclusion,BW of a calf may be well related to the efficiency of Holstein herds in Iran and which could beconsidered in the breeding and management programs. https://ijas.ut.ac.ir/article_32129_bcf2f66f664752357168c5899a82bccd.pdf