GENETIC DIVERSITY IN SLOVAK SPOTTED BREED

The objective of the study was to evaluate inbreeding and genetic diversity inSlovak Spotted cattle. Reference population contained genealogic information on36949 animals (129 sires and 36820 cows) that were used in the analyses. Pedigreecompleteness indexes in the first three generations were on the level of 100 %, inthe 5th generation it was 60 %. Since 1970, inbreeding trend was positive withsignificant increasing in 1990. Average relationship was 0.8 %, inbreeding rate0.36 % and ΔF = 0.094 %. In the reference population 43 % animals was inbred, 68% of sires and 33 % cows, with also 67 % purebred cows, as well. Total geneticdiversity loss in the reference population and population of cows was the same,closely under 1%, in purebred cows 1.19 % and sires even due to higher inbreedinglevel 1.78 %. Genetic diversity loss was more influenced by the genetic drift 0.80%in the reference population, 1.47% in sire group, than by effective number offounder unequal contributions. F statistic showed fines superiority ofheterozygosity by sire lines subpopulations, in the whole sire group (FIS = - 0.12)and their minimal differentiation (FST = 0,098). Obtained results showed thatinbreedization process started in this population. Monitoring and better geneticmanagement are important from the point of its further sustainable development.

The repeatability of textural wool handle

Merino breeders use textural greasy wool handle in ram buying and breeding decisions. The effectiveness of the current wool handle scoring system has not been objectively evaluated. The assessor repeatability of textural wool handle was quantified using three different methods of assessment (on the live animal, as a greasy wool mid-side sample, and as a clean (scoured) wool mid-side sample). The aim of the study was to determine which method of assessment is the most repeatable. Three separately defined repeatability estimates were calculated based on knowledge about the operator. The first estimate was based on the assessor repeatability from the operators used in this study. The second estimate was calculated using replicate values obtained from the same random assessor and the third estimate was based on two results from independent random assessors. The results demonstrated that the assessor repeatability was the greatest when handle was assessed on the clean wool mid-side method, followed by the greasy wool mid-side assessment, and least in the live-animal assessment. However, there was significant variation in the repeatability estimates between the four assessors used in the study. Accounting for fixed effects such as sex, sire group, birth type and rearing type, decreased the variation observed and thus had a negative impact on the assessor repeatability of textural wool handle. The results in this study indicate that non-wool constituents negatively impact on the ability of an assessor to consistently assign a score for textual handle in the greasy wool mid-side method. It is likely that the added cost and time required for scouring to assess handle in the clean state may not be economically viable in most situations. However, the increase in repeatability by assessing handle in greasy wool mid-side method compared with the live-animal assessment indicates that sheep producers should use this strategy when evaluating the trait on-farm.

Sire effects on neonatal lamb vigour and following-behaviour

The ability of the lamb to maintain contact with the ewe as she moves away from the birth site is critical to the lamb’s subsequent survival. If this contact is compromised then lamb loss is likely to occur due to starvation/mismothering. This study uses sires from the Sheep CRC Information Nucleus Flock to compare the effect of selection of sires within the Merino breed for high or low losses due to starvation/mismothering on neonatal lamb vigour. Lamb vigour was measured using conventional measures of time to perform early neonatal behaviours, early physiological measures (rectal temperatures and blood glucose), and performance in a modified barrier test while under physiological stress from cold exposure. Lambs were exposed to cold at a time (4–6 h after birth) when the ewe is likely to be moving away from the birth site and therefore when losses due to starvation/mismothering are likely to begin. Progeny from the high-loss sires were significantly (P < 0.05) slower to attempt to stand, and to stand, than progeny from the no-loss sires and tended to be slower to reach the udder and suckle (P = 0.07). Lambs from the no-loss group also had a significantly (P < 0.01) higher vigour score than the high-loss group. There was no effect of sire group on the performance of lambs in the modified barrier test; however, cold-treated lambs performed poorly in the test compared with control lambs. It was concluded that sire can have an effect on lamb vigour, but it does not necessarily translate into effects on later following-behaviour while under stressful conditions.

Comparison of Holstein bull semen sources on milk traits in Isfahan province in Iran

This research provides a comparison of productivity of daughters in Iran sired by bulls from Canada, Europe, Iran, and the United States. Data were collected by the Animal Breeding Center of Iran on pedigree and first lactation performances of 10,192 Holsteins sired by 186 imported (including: 39 European, 73 American, 74 Canadian) and 133 Iranian bulls, which had their first calving in 35 dairy herds in Isfahan province. The results showed that American and European daughters had the highest performances for milk yield. The highest mean for fat yield was related to European daughters. American sires on average had the highest genetic potential for yield traits; however, they had the lowest fat percentage among compared sire groups. Canadian sire group was intermediate relative to American, European and Iranian groups. Higher intercepts and regression coefficients of conversion equations for American sires showed that more returns will be achieved from one genetic point superiority of American sires relative to Canadian sires in the environments of Isfahan province. The Iranian sire group had the lowest predicted transmitting ability means for both milk and fat yields and a negative predicted transmitting ability mean for fat percentage. This study showed that due to low to intermediate predicted transmitting ability correlations between foreign evaluations and the evaluations made by this study, direct selection based on foreign national evaluations would not lead to optimal results for the traits concerned. So, the genetic potential/expression of imported genetic materials needs to be reevaluated by the Animal Breeding Centers of Iran.

Indices of cellular development in muscles of lambs are influenced by sire estimated breeding values and pastoral nutritional system

This study examined influences of sire (n = 9) estimated breeding values (EBVs), sire-group (Muscle, Growth, and Control), and nutrition (low and high quality and availability pasture) from birth to slaughter at ~8 months of age on indices of muscle cellularity and transcriptional and translational capacity in 56 castrate lambs. Effects of nutritional systems to 8 months of age were greater, overall, than those due to EBVs or sire-group. Amount of DNA increased with increasing EBV for post-weaning eye muscle depth (PEMD or Muscle EBV) in longissimus but not in semimembranosus and semitendinosus muscles, while Muscle EBV also had an inverse association with concentration of DNA. Protein to DNA and RNA to DNA were related positively to Muscle EBV, the associations being strongest for the semitendinosus muscle. Post-weaning weight (PWWT or Growth) EBV correlated positively with the RNA to DNA ratio and, among high but not low nutrition lambs, was inversely related to concentration of muscle DNA, whereas post-weaning fat depth (PFAT or Fat) EBV was correlated positively with RNA concentration. Overall, the magnitude of effects of sire-group was less than for sire EBVs, presumably due to differing selection pressures for muscling, fatness, and growth. High nutrition lambs had more protein to DNA than low nutrition lambs in the longissimus and semitendinosus muscles, but not in the semimembranosus muscle. In low compared with high nutrition lambs, concentration of DNA was greater in the longissimus and semitendinosus muscles. Total amount of DNA was reduced by more in low compared with high nutrition in the longissimus and semimembranosus than in the semitendinosus, and amount of protein was reduced by more in low compared with high nutrition in the longissimus than in the other two muscles. We conclude that genetic selection for eye muscle depth in sheep has differing effects on cellular characteristics of the longissimus, semimembranosus, and semitendinosus muscles, and has greater effects on muscle cellular characteristics than genetic selection for post-weaning weight or fat depth.

Dietary and Genetic Effects on LDL Size Measures in Baboons

Genetic and dietary effects on LDL phenotypes, including predominant LDL particle diameter, LDL size distribution, and non–HDL cholesterol and apoB concentrations, were investigated in 150 pedigreed baboons that are members of 19 sire groups. Baboons were fed a sequence of three defined diets differing in levels of fat and cholesterol. Increasing dietary fat had relatively little effect on two measures of LDL particle size. However, increasing the level of cholesterol in the diet resulted in larger increases of the predominant LDL particle diameters and in the proportion of stain on LDLs >28 nm. As expected, apoB and non–HDL cholesterol concentrations significantly increased when levels of dietary fat and cholesterol were increased. Correlations among the LDL phenotypes suggested that several different aspects of the LDL phenotype were captured by the four LDL measures across the three diets. Genetic effects indicated by sire group membership were significant both for expression of the LDL phenotypes and for response to changes in diet.

Effects of dam and sire group on the propensity for twin calving in cattle

ABSTRACTThe incidence of twin calvings and double ovulations was studied in two Milking Shorthorn herds and one Friesian herd, each with above-average annual twin calving rates (average 0·031, compared with a national rate of 0·01). The proportions of double ovulations were calculated from records comprising 1237 cow × years (cows over 2·0 years of age); means were 0·08, 0·27 and 0·50, for three groups which had previously produced 0, 1 or >1 sets of twins, respectively. All cows (whether still present or no longer in the herd) were then allocated a twin production status, to indicate the number of twin sets (0, 1 or >1) produced, or produced so far, in their lifetime. There were records from 1559 cows, with sire and dam also known. Twin production status was significantly influenced by dam group (P < 0·01), i.e. the twin production status of the cow's dam. Sires were classified into two groups, according to whether any daughters had produced two or more sets of twins. After allowing for ascertainment, sires in the two groups were found to differ (P < 0·01) by 0·06 in the probability of their daughters producing at least one set of twins in their lifetime (i.e. 0·08 to 0·14). One sire and dam combination in particular had prolific daughters with a probability of 0·39 of producing at least one set of twins in their lifetime (compared with a probability of 0-07 for the other extreme combination). The possibility of these observations being explained by the segregation of a single recessive gene was considered, but the necessary interaction between sire group and dam group was not significant.

EFFECT OF HERD-YEAR PRODUCTION LEVEL ON EXPRESSION OF SIRE MERIT

Performance data on 110 602 first lactation Holstein cows were utilized to compare the expressions of sire proof at various herd-year production levels. Production traits analyzed were BCA milk, BCA fat and fat percentage. Herd-year averages were partitioned into six groups for each trait. Regression analysis indicated significant interactions between herd-year level and sire estimated transmitting ability (ETA) for daughter milk and fat BCA (P < 0.001). Interaction between herd group and sire proof for fat percentage was found to be insignificant. Linear contrasts were used to compare sire proof slope differences for various herd-year group comparisons. Regression coefficients for sire proof tended to increase as herd-year level increased for both milk and fat yield. The coefficient for sire fat percentage was smaller for the lowest herd-year level when compared to other herd levels. Sire proofs for milk and fat were than categorized into six and seven groups respectively. Sire group and herd-year by sire group interaction were found to account for a significant (P < 0.01) amount of variation in daughter milk and fat yield. Linear contrasts were also used to compare specific sire group differences at various herd production levels. Significant herd-year differences were observed for both daughter milk and fat yield. However specific trends were not prevalent for sire group differences as herd-year groups increased for both traits. Key words: Dairy, sire, daughter

THE INTERACTION OF COW SIZE WITH GROWTH POTENTIAL OF THE SERVICE SIRE

Weaning weight and individual feed records for 343 calves produced by 84 cows during an 8-yr period were utilized to evaluate the effects of high- and low-growth-potential sires on the efficiency of large and small cows. Cow efficiency was expressed as a ratio of cows' and calves' TDN consumption for a year divided by the weaning weight of the calf. The design allowed the mating of small and large cows of each of four breed groups to unrelated low- and high-growth-potential bulls. The effects of cow size on cow efficiency were further evaluated by omitting cow size group and the interaction of cow size with sire group from the model and replacing them with the linear and quadratic effects of cow weight and subclass regressions of efficiency on cow weight within sire groups. Results indicated no interaction of cow size with growth potential of the bull, and no effect of cow size group but a significant effect of growth potential of the bull. The inclusion of milk production as a dependent variable indicated that cows produced 0.6–0.8 kg d−1 more milk when bred to the high-growth-potential bull group. None of the quadratic or linear regression coeficients were significant but the subclass regression of cow efficiency on cow weight within the high-growth-potential bull was significantly different from zero and from the coefficient for low-growth-potential bulls. These effects were in the direction which agrees with the concept of complementarity but their values were rather small. Further experimental evaluation of this kind with greater range in weight of sire and dam would be desirable. Key words: Cow efficiency, complementarity, beef cattle