ABSTRACT
The study was conducted (July, 2011 - June, 2012) to determine the influence of age and body condition on semen quality, testicular and body dimensions in Red Sokoto goats of two hair types using 31 Red Sokoto bucks. The ages of the bucks were categorized into four; 9 -12, 13-16, 17-20 and 21-24 months. The hair types were categorized into short-smooth (SS) and long-curly (LC). The body condition was scored and categorized as score 3 and 4. Weight records and linear body measurements were obtained. Testicular length and testicular circumference were measured using flexible tape while testicular width and testicular weight were estimated using the appropriate formulae. The semen trait, sperm morphological defects and semen cation concentrations were evaluated accordingly. The results showed that the mean BW, HG, ST, CW, WH, BD, BL, RW, TL, TC, TW and TWT were 15.02 Kg, 59.9 cm, 54.95 cm, 8.37 cm, 53.41 cm, 32.86 cm, 57.35 cm, 17.03 cm, 12.00 cm, 17.38 cm, 5.53 cm and 203.04 g; while 0.52, 0.64, 0.52, 1.03, 0.61, 94.90, 67.79, 2.62, 5.42 were for DMT, MPD, DH, CBT, ACR, Na, K, Ca and PO4, respectively. Semen volume, sperm motility, semen pH, sperm concentration and live & dead ratio were 0.42 ml, 79.52 %, 8.85, 701.13 x 106/ml and 0.82 %, respectively. Age and BCS significantly (P<0.01) influenced BW, body conformation and testicular traits, but had a variable influence on semen traits. DMT, MPD and CBT were more frequent in younger-matured bucks of between 13 and 20 months of age than bucks of later ages while DH and ACR occurred in the younger (9 - 12 months) and older bucks (21 - 24 months of age). Semen cation concentrations were relatively higher in the older bucks of 21 - 24 months than the younger bucks except for Na+ which was also high in younger bucks of 9 - 16 months. Hair type had influence (P<0.01) on some testicular traits. Long-curly haired bucks had the highest DMT and CBT, while the short-smooth haired bucks had the highest DH. Bucks with lower BCS showed higher DH than bucks with higher body condition. Body measurements correlated positively and significantly with testicular measurements (0.25 - 0.61). Body (0.27 - 0.45) and testicular (0.25 - 0.39) measurements were positively correlated to some semen traits. Relationship between semen cations and sperm morphological traits were generally negative and significant (r = -0.28 to -0.40) except ACR which was positively and significantly correlated with Ca2+ (r = 0.37). Semen volume was positively and significantly correlated with K+ and Ca2+ (P<0.05; r = 0.27 - 0.31). Sperm motility was positively and significantly correlated with Na+ and K+ (P<0.05; r = 0.26 - 0.33). Ca2+ was positively and significantly correlated with testicular measurements (P<0.05; r = 0.34 - 0.39). Bucks with BCS 4 were bigger in size (HG, ST, WH, BL, RW) and weighed more (BW) and had scrotum that were longer (TL), broader (TC), wider (TW) and heavier (TWT); hence produced more semen (SV) with higher concentration of Na than those with BCS 3. Bucks aged 21-24 months with short-smooth hair and higher body condition gave better testicular dimensions and exhibited less occurrence of sperm abnormality than the young, long-curly haired and lower body condition bucks. Therefore, bucks aged 21-24 months with larger body and testicular size can be exploited for optimum breeding performance. When considering hair type as an indicator of semen quality, short-smooth haired bucks could be used as selection criteria in Red Sokoto goats.
