The objective of the present study was to estimate genetic parameters for economic traits in Markhoz goats. Data collected from 1993 to 2006 by the Markhoz goat Performance Testing Station in Sanandaj, Iran, were analyzed. The traits recorded as body weight performance at birth (BW), weaning (WW), six month (6MW), nine month (9MW), yearling (YW) and yearling fleece weight (YFW) were investigated. Least square analyses were used for estimation of environmental effects. Genetic parameters were estimated with single and multi trait analysis using restricted maximum likelihood (REML) procedures, under animal models. By ignoring or including maternal additive genetic effects and maternal permanent environmental effects, five different models were fitted for each trait. The effects of sex, type of birth, age of dam and year of birth on the all body weights were significant (p<0.01), but had no effects on YFW except year of birth. Age of kids had significant influences on WW and 6MW (p<0.01). A log likelihood ratio test was carried out for choosing the most suitable model for each trait. Total heritability estimates for YFW and growth traits varied from 0.16 for YFW and WW to 0.41 for YW. For all traits, maternal heritability was lower than direct heritability, ranging from 0.06 for BW to 0.01 for 6MW and 9MW. The magnitude of c 2 was more substantial for BW than the others, and relative importance was reduced from 0.12 for BW to 0.04 for 9MW. The direct additive genetic correlations estimates were positive and varied from 0.21 between BW-YW to 0.96 between WW-6MW. Direct additive genetic correlations between YFW and body weight traits were positive and ranged from 0.14 between BW-YFW to 0.67 between 6MW-YFW. For all traits, the corresponding estimates for phenotypic correlation were positive and lower than genetic correlations. The maternal additive genetic correlations between various traits were varied and ranged from -0.19 between 9MW-YFW to 0.96 between 6MW-9MW. The estimates of the maternal permanent environmental correlations between various traits were positive and ranged from 0.33 between WW-YFW to 0.93 between WW-6MW. Also, the environmental correlations between various traits ranged from 0.01 between BW-YFW and WW-YFW to 0.70 between 9MW-YW. Estimates of genetic parameters for various traits in this study confirm that selection should be applied on WW for genetic improvement in Markhoz goats.

The effect of thawing velocities ranging from 10 degrees C/min to 1,800 degrees C/min on the motility and acrosomal integrity of boar spermatozoa frozen at 1 degree C/min (suboptimal), 5 degrees C/min, and 30 degrees C/min (optimal) rate was studied with the sperm suspended for freezing in diluent containing 2, 4, or 6% of glycerol (v/v). The influence of thawing on sperm survival depends on the rate at which the sperm had been frozen. In semen frozen at a suboptimal rate of 1 degree C/min, the percentage of motile sperm (FMP) initially fell to 3.5-4.0% when the thawing rose to 200 degrees C/min, but, with further increases in thawing rate, increased and reached peak values (10.3-11.0% FMP) after thawing at 1,800 degrees C/min. The percentage of sperm with normal apical ridge (NAR) also increased moderately with thawing rate, but the degree of improvement decreased as the glycerol level was increased. In semen frozen at 1 degree C/min, acrosomal integrity (NAR) was best maintained in 2% glycerol, reaching 22.9% NAR after thawing at 1,800 degrees C/min. In semen frozen at the optimal rate of 30 degrees C/min, the increases in thawing rates above 200 degrees C/min substantially improved motility. Motility was generally higher in semen protected by 4 or 6% glycerol, with the peak values of 44 or 46% FMP, respectively, after thawing at 1,200 degrees C/min. The proportion of sperm with NAR also increased with thawing rate, but as in the case of suboptimally frozen sperm it was influenced negatively by the glycerol concentration.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult rams were exposed to photoperiod treatments over 2 years to study the influence of light regimes on pituitary-testicular activity and semen quality. Initially, all rams (12 per group) were exposed to 3 months of long days (16L:8D). Group 1 was then exposed to a regime of continuous short days (8L:16D) and Groups 2, 3, and 4 were exposed to 4 months of short days alternated with 1, 2, or 4 months, respectively, of long days. Every 2 weeks, serum hormone levels and scrotal circumference were determined and semen quality was evaluated. Regular cycles in pituitary and testicular activities corresponding to the period of the lighting regime resulted in Groups 2, 3, and 4, but not in Group 1. In general, the change from long days to short days induced increases in follicle-stimulating hormone (FSH), luteinizing hormone (LH), and testosterone levels, scrotal size and sperm numbers and a decrease in prolactin. The reverse occurred after subsequent exposure to long days. After 4 months of long days, testicular regression was complete, but when long-day exposure was reduced, less regression occurred. With continuous exposure to short days, FSH and testosterone remained above basal levels, prolactin levels were depressed, scrotal size remained near the maximum, and elevated numbers of motile sperm were sustained.

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Ultrasonic measurements of fat thickness and m. longissimus depth 25 and 50 mm lateral to the mid line at the last rib and 100 mm caudally to the last rib were made, before slaughter, on 273 ram lambs using two probes: the Scanogram and Krautkramer. The lambs were from three strains: a meat-type sire strain and two fecund dam strains. They weighed on average 37·3 kg at scanning, (range 29·0 to 51·3 kg), well within the weight range over which Canada Al-grade lambs are marketed in Canada. Their carcasses contained on average 437 g trimmed boneless meat per kg (s.d. pooled within strain = 24·1 g/kg).The precision with which the ultrasonic measurements combined with live weight at scanning predicted trimmed boneless meat (weight and proportion) was examined. Fat thickness measurements had no predictive value (P > 0·05). The residual standard deviations for the prediction of trimmed boneless meat in the half carcass (weight and proportion) from weight at scanning were 0·29 kg and 21·5 kg, respectively; the addition of the m. longissimus depth measurement reduced the residual standard deviations by 0·02 kg and 1·1 g/kg, respectively. The weight of trimmed boneless meat was predicted with more precision than the proportion of trimmed boneless meat. Strain, location of measurement site or type of instrument did not change the precision of prediction.It is concluded that prediction of trimmed boneless meat in young ram lambs based on live animal ultrasonic measurements made with the Scanogram or Krautkramer lacks the level of precision necessary for practical application.