A Study on status of heifer rearing (From weaning to calving period) in dairy cattle farms of Isfahan Province.

This study carried out to evaluate feeding and rearing management of replacement heifers in modern dairy farms of Esfahan Province. First , information of active farms obtained from Organization of Jihad-e Agriculture of the province which showed 477 active dairy farms. The farms classified into 5 categories based on population of milking cows including 20 50, 51 100, 101 150, 151 300 and above 301 heads. According to the Random Classification Sampling Method and based on appropriate assign, 15 to 20 percent of all the farms selected for study (totally 93 farms). Then, direct information of feeding and rearing management status obtained by completing the questionnaires, every two months. Also, required information collected about average dairy gain and performance of reproduction such as body weight, age , wither height , body condition score (BCS) at successful insemination time and feed intake for all the categories. Tables of NRC (2001) used to define nutrient requirement of the studied animals (Holstein breed) at ages of 3, 6, 9, 15, 18, 21 and 21 month. Then , obtained averages for estimated nutrient intake compared by t test. Results showed that studied animals in all the categories , age groups had no difficulties for dry matter intake , metabolizable energy. However, fed rations compared to NRC (2001) supplied excess NDF, ADF, Ca, P, K, Na and Cl (P 0.05). Comparison between required and supplied crude protein and sulfur showed deficiency for all the age groups. Average age at successful insemination time , age at calving, live weight at insemination time, and live weight at calving were 16.10 2.4 month, 25.20 2.28 month, 367 53 kg. , and 583 44 kg., respectively, which showed no significant differences for criteria of live weight at insemination and calving time. It can be concluded that management level in categories1 of 2 and 3 is weak and criteria of reproduction and nutrition show far gaps (differences) compared to standards. Keyword: Replacement heifer, metabolizable energy, crude protein, feeding management , Esfahan. modern dairy farms