title: Effects of growth and dietary crude protein level until first insemination on milk production during first lactation in Holstein heifers.
abstract: To decrease the age at first calving in Holsteins, the effects of average daily body weight gain (ADG) and crude protein (CP) level until first insemination on growth performance and milk production were examined. The MM group had a target ADG of 0.75 kg and received a diet with a CP level of 14%. The HM and HH groups had a target ADG of 1 kg; both these groups received a diet with CP levels 14% and 16%, respectively. The ADG in the HM and HH groups was 1.1 kg, whereas in the MM group it was 0.97 kg (P < 0.01). The HM and HH groups showed no differences in withers height at body weight 350 kg. The ages at first calving in MM, HM and HH groups were 23.1, 21.0 and 21.8 months, respectively. The HM and HH groups had lower milk yield at day 305 than the MM group (P < 0.01). These results suggest that growth performance until first insemination should be maintained at an ADG of 0.97 kg or less with a CP level of approximately 14%, to shorten time until first insemination and prevent the decrease of milk yield.
authors: Ibaraki Prefectural Livestock Research Center, Ishioka, Japan.
authors: Takashige
authors: T
authors: Ishii
authors: Kenji
authors: K
authors: Kawashima
authors: Haruo
authors: H
authors: Oribe
authors: Hiromi
authors: H
authors: Ueda
authors: Toshiya
authors: T
authors: Hasunuma
authors: Kiyoshi
authors: K
authors: Akiyama
authors: Hirofumi
authors: H
authors: Nakayama
authors: Mitsunori
authors: M
authors: Kurihara
authors: Fuminori
authors: F
authors: Terada
authors: Shiro
authors: S
authors: Kushibiki
mesh_terms: D000367:Age Factors; D000818:Animals; D002417:Cattle / Q000254:growth & development / Q000502:physiology*; D004044:Dietary Proteins / Q000008:administration & dosage*; D005260:Female; D007314:Insemination / Q000502:physiology*; D007774:Lactation / Q000502:physiology*; D008892:Milk / Q000378:metabolism*; D015430:Weight Gain / Q000502:physiology
chemical_list: D004044:Dietary Proteins