Serhat Karaca

Use of factor analysis scores in multiple linear regression model for determining relationships between milk yield and some udder traits in goats

Abstract Keskin, S., Kor, A. and Karaca, S. 2007. Use of factor analysis scores in multiple linear regression model for determining relationships between milk yield and some udder traits in goats. J. Appl. Anim. Res., 31: 185–188. In present study, the relationships between daily milk yield (DMY) and 10 udder traits (upper height, bottom height, depth, width, circumference, left and right teat length, left and right teat circumference, teat angle) were examined by using of factor analysis scores in multiple linear regression model. Four factors (teat, udder and height measurements and teat angle) with eigenvalues greater than 1 were selected as independent or explanatory variables and used for multiple linear regression analysis. It was found that four factors had significant effects on daily milk yield and these factors together accounted for 75.4% of variation in daily milk yield.

Effects of pre-slaughter diet/management system and fasting period on physiological indicators and meat quality traits of lambs.

This study determined the effects of pre-slaughter diet/management system on blood and rumen parameters and meat-quality traits of Norduz lambs. Eighty lambs were divided into two groups according to diet (AH: alfalfa hay; BAH: alfalfa supplemented with 500 g/head barley) for 21 days. Following this period, lambs from each group were distributed among four groups according to pre-slaughter fasting period as 0, 12, 24 or 48 h. Cortisol concentrations were found to be significantly higher in the 24 h and 48 h groups when compared to the 0 h group (p<0.01). Diet and fasting period had limited effect on muscle glycogen content and ultimate pH·L*, WHC and moisture decreased in line with increases in the fasting period (p<0.01). In conclusion, carcass conformation and some meat quality traits were better in BAH lambs. Fasting had a negative effect on some meat quality parameters, with significant increases in some physiological stress indicators after fasting periods of 24 h or longer.

Effects of pre-slaughter ascorbic acid administration on some physiological stress response and meat quality traits of lambs and kids subjected to road transport

The present study determined the effects of pre-slaughter ascorbic acid administration on some physiological indicators and meat quality traits of road transport-stressed lambs and kids. Eighteen lambs and 18 kids were divided into the following three groups: no transportation (T0), 3-h transportation (T3), and ascorbid acid administered at 125 mg/kg before 3-h transportation (T3+C). The liveweight loss and rectal temperature were similar, while there were significant differences among groups for some biochemical parameters in both lambs and kids. Glucose concentrations significantly increased after transportation in lambs (P = 0.005) and kids (P < 0.001). Ascorbic acid had significant effects on serum glucose of lambs. T3 lambs had higher glucose concentrations than did T0 lambs (P < 0.001), while T0 and T3+C lambs were found to have similar concentrations. Oxidative status in lambs and kids, as determined by serum malondialdehyde concentration, did not differ among groups. However, some meat quality traits were negatively influenced by transportation. T3 lambs had a significantly lower muscle glycogen concentration than did T0 and T3+C lambs (P = 0.018), while ultimate pH was similar among groups. Muscle glycogen concentration was significantly lower (P = 0.008) and ultimate pH was higher in T3 and T3+C kids (P = 0.028). T3 and T3+C groups had darker meat (L*) than did T0 groups both in lambs and kids, whereas a*, cooking loss and water-holding capacity were similar among groups. The effect of ascorbic acid on meat toughness was significant and shear force value in T0 lambs was lower than that in T3 lambs (P = 0.009), while T0 and T3+C lambs were found to have similar shear force values. Overall, the administration of ascorbic acid to lambs before transportation could partly reduce the adverse effects of road transportation stress, whereas its effects on kids were found to be insignificant.

Relationships between physiological and behavioral responses of goat bucks in mating season

The objective of this study was to determine the sexual parameters in young bucks with different sexual activity and the effect of experience (age) on sexual parameters in bucks. Fifteen young, sexually inexperienced (SI) and five adult, sexually experienced (SE) Saanen × Hair goat crossbred bucks were used in this study. Bucks were individually exposed to three estrus does for 15-min periods during four sexual performance tests, which were carried out every other day to determine some sexual behavior traits such as flehmen response, reaction time, and ejaculation efficiency. Sexually inexperienced young bucks were evaluated based on their sexual activity (active (AC) vs inactive (IA)) and presence of horn. It was found that AC bucks had significantly higher serum testosterone concentrations (31.5 vs 21.5 ng/mL) and weight loss (114.2 vs 51.2 g/day) than IA bucks. In addition, weight loss was significantly correlated with ejaculation efficiency in young bucks. On the other hand, horned bucks tended to have higher ejaculation efficiency with significantly longer reaction time than polled bucks. For experience (age) classes, SE bucks had higher testosterone concentration (76.0 vs 31.5 ng/mL) and weight loss (16.7 vs 8.6%) than SI active young bucks. However, the effect of experience on other sexual performance traits was found to be limited. Overall, these results indicate that testosterone concentration may affect sexual performance of young bucks in the mating season. Age-related sexual experience is not a determining factor for sexual performance in bucks. However, sexual performance data alone may not reflect reproductive outcomes without semen data.