title: Effect of protein supplementation on reproductive and productive performance in Bos indicus x Bos taurus heifers raised in the humid tropics of Costa Rica.
abstract: In order to evaluate the effect of protein supplementation on the productive and reproductive performance of heifers, 45 Bos indicus x Bos taurus heifers, 673 +/- 146 days of age and weighing about 340 kg, were divided into two groups. The control group (n = 23) continued without supplementation, but the supplemented group (SG; n = 22) received concentrate at a rate of 1% BW kg per day. Animals were adapted to the concentrate over a 15-day period and then supplemented for 30 days, after which estrus was synchronized using a progesterone implant. Back fat thickness (BFT) was assessed by ultrasound. The SG had better average daily weight gain than the nonsupplemented group (0.63 +/- 0.16 vs. 0.51 +/- 0.13 kg/day, P < 0.05) and tended to show a better percentage ovulation (P < 0.10, 77% vs. 57%, respectively). However, this tendency was not reflected in the final pregnancy rates. No differences were observed between groups in dry matter intake and body condition scores. SG with a high BFT (>0.70 cm) showed a better ovulation percentage than those with low BFT (<0.69 cm; P < 0.01). Additionally, the pregnancy rate of supplemented heifers with high BFT tended to be better than heifers with low BFT in this same group (67% vs. 30%, respectively, P < 0.10). It is concluded that protein supplementation improved reproductive performance and that ultrasonography to measure BFT may be used to estimate reproductive performance.
authors.affiliation: Department of Animal Science, The Ohio State University, 2029 Fyffe Road, Columbus, OH 43210-1095, USA.
authors.forename: Martin G
authors.initials: MG
authors.lastname: Maquivar
authors.forename: Carlos S
authors.initials: CS
authors.lastname: Galina
authors.forename: Jaime R
authors.initials: JR
authors.lastname: Galindo
authors.forename: Sandra
authors.initials: S
authors.lastname: Estrada
authors.forename: Rafael
authors.initials: R
authors.lastname: Molina
authors.forename: German David
authors.initials: GD
authors.lastname: Mendoza
mesh_terms: D000273:Adipose Tissue / Q000000981:diagnostic imaging; D000824:Animal Nutritional Physiological Phenomena / Q000502:physiology*; D000818:Animals; D001835:Body Weight / Q000502:physiology; D002417:Cattle / Q000502:physiology*; D016009:Chi-Square Distribution; D003364:Costa Rica; D019587:Dietary Supplements; D005260:Female; D010060:Ovulation / Q000502:physiology*; D011897:Random Allocation; D014329:Tropical Climate; D014463:Ultrasonography