98 CONCEPTION RATES USING BRAHMAN BULL SEMEN FROZEN IN MILK BASED EXTENDER CONTAINING EGG YOLK OR SOYBEAN LIPIDS; A FIELD STUDY IN A TROPICAL ENVIRONMENT
R. Gonzales A B , M. Rosales C , F. Perea C , J. Velarde B , E. Soto A B , R. Palomares A , H. Hernandez A and A.T. Palasz DA Facultad de Ciencias Veterinarias, Universidad del Zulia, Venezuela;
B Venezolana de Inseminación Artificial y Transplante de Embriones, C.A. (Viateca), Venezuela;
C Departamento de Ciencias Agrarias. Universidad de los Andes, Venezuela;
D Departamento de Reproducción Animal. INIA, Madrid, Spain. email: palasza@yahoo.ca
Reproduction, Fertility and Development 16(2) 170-171 https://doi.org/10.1071/RDv16n1Ab98
Submitted: 1 August 2003 Accepted: 1 October 2003 Published: 2 January 2004
Abstract
The objective of this study was to examine the substitution of soybean-origin phospholipids for egg yolk in Brahman bull semen extender. Semen was frozen in 3 different low-fat milk (1%) based extenders containing 10 mg mL−1 of fructose and supplemented with: 8% of whole egg yolk (Extender 1, control), 8% rectified egg yolk (egg yolk granules were removed by double centrifugation at 3000g for 1 h at 5°C; Extender 2), and 7.3 mg mL−1 of phospholipids of soybean-origin containing 10% of phosphatidyl choline (Extender 3). All 3 extenders were supplemented with 1000 IU of penicillin, 1 mg mL−1 streptomycin and 150 μg mL−1 lincomycin. The semen was collected by means of artificial vagina from 3 Brahman bulls, and AI was performed during the dry season between December and April in a tropical forest environment. The mean temperature for the region was 26–30°C, with mean rainfall of 900–1500 mm/year and the relative humidity of 60–70%. Ejaculates with at least 60% motility were diluted in 2 steps as follows: in step 1, each ejaculate was split into 3 even parts and diluted at 26°C with each of the extenders containing no glycerol, and in step 2, 14% of glycerol was added in 15-minute intervals to a final glycerol concentration of 7%. Semen was aspirated into 0.5 mL plastic straws (20 × 106 sperm/per straw), frozen 7 cm above liquid nitrogen (LN2) for 8 min, and then plunged into LN2. Straws were thawed in a water bath at 37°C for 30 s. Each experiment was replicated 3 times (different collection days). Sperm viability was tested within artificial insemination trials. Results are based on the pregnancy rates of crossbreed Brahman cows determined by palpation 45 Days after AI and by calving rates. Data were compared by chi-square analysis. In Experiment I, a total of 157 cows were inseminated with semen collected from 3 different bulls (A, B and C) and frozen in 3 different extenders (1, 2 and 3; 3 × 3 factorial design). Bull A, Extender 1, 2 and 3 (n = 19, 20 and 22); Bull B, Extender 1, 2 and 3 (n = 20, 20 and 20) and Bull C, Extender 1, 2 and 3 (n = 22, 15 and 24), respectively. Although semen from all 3 bulls frozen in Extenders 2 and 3 fostered numerically higher pregnancy rates (from 30% for Bull B and Extender 2 to 50% for Bull C and Extender 3) than in Extender 1 (from 23.5% for Bull C to 40% for Bull B), there were no differences (P < 0.05) between bulls with any of 3 extenders on the pregnancy rates. In Experiment II, a total of 117 cows were inseminated with semen collected from Bull B and frozen in Extender: 1 (n = 37), 2 (n = 48) and 3 (n = 39). There were significantly higher (P < 0.05) calving rates for cows inseminated with semen frozen in Extender 2 and 3 (41.6% and 46.1%, respectively) than in Extender 1 (24.3%). It can be concluded that rectified egg yolk may improve viability of frozen semen, and that phospholipids of soybean origin can be successfully substituted for egg yolk in Brahman bull milk based semen extender. Supported by Bioniche Inc, Belleville, Ontario, Canada.
