INFLUENCE OF FAT SUPPLEMENTATION ON LH PULSES AND FSH CONCENTRATION IN NELLORE HEIFERS
The aim of this study was to verify whether protected fat supplementation, after weaning increases LH pulses and FSH concentration in Nellore heifers (Bos taurus indicus). Contemporary heifers (n=30; 167±13 kg; 9 months) were sorted into 3 experimental groups: Control Group (CG, n=10), sugar cane bagasse plus 4.2 kg concentrate and 500g of ground corn; Fat Group (FG, n=10), sugar cane bagasse, plus 4.2 kg of concentrate and plus 200g of rumen protected fat (Ca salts of soybean oil); and Excess Group (EG, n=10), sugar cane bagasse plus 4.2 kg of concentrate, 500 g of ground corn plus 200 g of rumen protected fat per animal per day (13.85% of palmitic acid, 17.92% of oleic acid and 49.09% of linoleic acid). After an adaptation period, animals remained under nutritional treatments for 92 days (13th to 16th month of age). Blood samples were collected every 24 hours during 17 days, in 10th, 12th, 14th and 16th month of age, and every 20 min per 12 hours on 11th, 13th, 14th e 16th month of age for FSH and LH quantification. The results were evaluated by repeated measures ANOVA and the Duncan´s test was the post-test of SAS®. During the treatment, the FG presented a higher number LH pulses (3.12 ±1.64; p=0.05) in comparison with EG (1.86 ± 0.90) and CG (2.63 ± 0.74), from samples collected every 20 minutes per 12 hours. The CG showed higher FSH concentration area (15.71±3.72 ng/ml/day), p=0.06) than GG (11.23±2.51 ng/ml/day) and EG (14.17±4.22 ng/ml/day) at the 14th month of age. There was no difference on FSH concentration area between groups in 10th (p=0.80), 12th (p=0.55) and 16th (p=0.35) month of age. The CG showed higher FSH amplitude (1.86±0.72 ng/ml, p=0.08) than GG (1.12±0.51 ng/ml) and EG (1.54±0.22 ng/ml) also at the 14th month of age. There was no difference on FSH amplitude between groups at the 10th (p=0.89), 12th (p=0.78) and 16th(p=0.36) month of age. We concluded that fat treatment increased frequency LH pulses, decreased FSH amplitude and FSH concentration area during supplement period.
Keywords: Bos indicus, LH, pulses, FSH, fat, supplementation