Effect of protein supplementation on reproductive and productive performance in <Emphasis Type="Italic">Bos indicus</Emphasis> × <Emphasis Type="Italic">Bos taurus</Emphasis> heifers raised in the humid tropics of Costa Rica |
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Authors: | Martin G Maquivar Carlos S Galina Jaime R Galindo Sandra Estrada Rafael Molina German David Mendoza |
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Institution: | 1.Department of Animal Science,The Ohio State University,Columbus,USA;2.Departamento de Reproducción, Facultad de Medicina Veterinaria y Zootecnia,Universidad Nacional Autónoma de México,Mexico,Mexico;3.Escuela de Agronomía,Instituto Tecnológico de Costa Rica,San Carlos,Costa Rica;4.Salud de Hato, Escuela de Medicina Veterinaria,Universidad Nacional de Costa Rica,Heredia,Costa Rica;5.Departamento de Producción Agrícola y Animal,Universidad Autónoma Metropolitana,Mexico,Mexico |
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Abstract: | In order to evaluate the effect of protein supplementation on the productive and reproductive performance of heifers, 45 Bos indicus × 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. |
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