98CONCEPTION RATES USING BRAHMAN BULL SEMEN FROZEN IN MILK BASED
EXTENDER CONTAINING EGG YOLK OR SOYBEAN LIPIDS; A FIELD STUDY IN A TROPICAL
ENVIRONMENT
Authors: Gonzales R. , Rosales M. , Perea F. , Velarde J. , Soto E. , Palomares R. , Hernandez H. , Palasz A.T. 
Published: February 2004

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 10mgmL−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 1h at 5°C; Extender 2), and 7.3mgmL−1 of phospholipids of soybean-origin containing 10% of phosphatidyl choline (Extender 3). All 3 extenders were supplemented with 1000IU of penicillin, 1mgmL−1 streptomycin and 150μgmL−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 900–1500mm/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 0.5mL plastic straws (20×106 sperm/per straw), frozen 7cm above liquid nitrogen (LN2) for 8min, and then plunged into LN2. Straws were thawed in a water bath at 37°C for 30s. 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&lt;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&lt;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.