Genetic parameters for birth weight,growth, and litter size in Nordic sheep breeds

Abstract

In this study, genetic parameters were estimated for the Danish populations of Danish Marsk, Finnish Landrace, Gotland Pelt and Spel for birth weight (BW), average daily gain until two months (DG2) and litter size (LS). A multivariate animal model was used for estimation of genetic parameters, including fixed effects, both direct and maternal additive genetic effects, common litter effects and permanent environmental effects. Mean birth weight and DG2 ranged from, respectively, 3.39 kg and 262 g to 4.61kg and 286 g. Litter size ranged from 1.60 to 2.07. Direct heritability for BW ranged from 0.12 to 0.24, and maternal heritability for BW was about 0.23 for all breeds. Direct heritability of DG2 ranged from 0.19 to 0.33. The heritability for LS was between 0.08 and 0.13. The significant genetic correlations between the direct and maternal effect on both BW and DG2 were negative. The genetic correlations between the growth traits and LS were not uniform.     

Genetic parameters of pelt character,feed efficiency and size traits in Finnish blue fox (Vulpes lagopus)

Pelt character traits (size, quality, colour clarity, darkness) are important economic traits in blue fox breeding. Better feed efficiency (FE) is another economically important and new breeding goal for fur animals. The purpose of this study was to determine the correlations between pelt character traits, FE and size traits and to estimate genetic parameters for pelt character traits. Pelt size (pSI_cm) had a high positive genetic correlation with animal grading size (gSI), final body weight (BW_Fin), body length and daily gain (DG), and a moderate correlation with body condition score (BCS). Animal body length and BCS (describing fatness) were considered as genetically different traits. Genetic correlations between pelt quality and size traits were estimated without precision and did not differ from zero, but colour clarity (pCL) had a low antagonistic genetic correlation with FE. Pelt size and DG had a favourable genetic correlation with FE but a fairly high unfavourable genetic correlation with dry matter feed intake. The current emphasis on selection for larger animal and pelt size improves FE indirectly, but selection for larger pelt size favours fast‐growing and fat individuals and simultaneously increases feed intake. The detected genetic connections between FE, size, feed intake and pCL should be taken into account in the Finnish blue fox breeding programme.     

Genetic parameters and trends for production traits and their relationship with litter traits in Landrace and Yorkshire pigs

Genetic parameters and trends in the average daily gain (ADG), backfat thickness (BF), loin muscle area (LMA), lean percentage (LP), and age at 90 kg (D90) were estimated for populations of Landrace and Yorkshire pigs. Additionally, the correlations between these production traits and litter traits were estimated. Litter traits included total born (TB) and number born alive (NBA). The data used for this study were obtained from eight farms during 1999 to 2016. Analyses were carried out with a multivariate animal model to estimate genetic parameters for production traits while bivariate analyses were performed to estimate the correlations between production and litter traits. The heritability estimates were 0.52 and 0.43 for ADG; 0.54 and 0.45 for BF; 0.25 and 0.26 for LMA; 0.54 and 0.48 for LP; and 0.56 and 0.46 for D90 in the Landrace and Yorkshire breeds, respectively. The ADG and D90 showed low genetic correlation with BF and LP. The LMA had ?0.40, ?0.32, 0.49, and 0.39 genetic correlations with ADG, BF, LP, and D90, respectively. Genetic correlations between production and litter traits were generally low, except for the correlations between LMA and TB (?0.23) in Landrace and ADG and TB (?0.16), ADG and NBA (?0.18), D90 and TB (0.19), and D90 and NBA (0.20) in Yorkshire. Genetic trends in production traits were all favorable except for LMA.     

Genetic correlations among and between wool, growth and reproduction traits in Merino sheep

Summary Data from seven research resource flocks across Australia were combined to provide accurate estimates of genetic correlations among production traits in Merino sheep. The flocks represented contemporary Australian Merino fine, medium and broad wool strains over the past 30 years. Over 110 000 records were available for analysis for each of the major wool traits, and 50 000 records for reproduction and growth traits with over 2700 sires and 25 000 dams. Individual models developed from the single trait analyses were extended to the various combinations of two-trait models to obtain genetic correlations among six wool traits [clean fleece weight (CFW), greasy fleece weight, fibre diameter (FD), yield, coefficient of variation of fibre diameter and standard deviation of fibre diameter], four growth traits [birth weight, weaning weight, yearling weight (YWT), and hogget weight] and four reproduction traits [fertility, litter size, lambs born per ewe joined, lambs weaned per ewe joined (LW/EJ)]. This study has provided for the first time a comprehensive matrix of genetic correlations among these 14 wool, growth and reproduction traits. The large size of the data set has also provided estimates with very low standard errors. A moderate positive genetic correlation was observed between CFW and FD (0.29 ± 0.02). YWT was positively correlated with CFW (0.23 ± 0.04), FD (0.17 ± 0.04) and LWEJ (0.58 ± 0.06), while LW/EJ was negatively correlated with CFW (−0.26 ± 0.05) and positively correlated with FD (0.06 ± 0.04) and LS (0.68 ± 0.04). These genetic correlations, together with the estimates of heritability and other parameters provide the basis for more accurate prediction of outcomes in complex sheep-breeding programmes designed to improve several traits.     

Bayesian analysis of birth weight and litter size in Baluchi sheep using Gibbs sampling

Variance and covariance components for birth weight (BWT), as a lamb trait, and litter size measured on ewes in the first, second, and third parities (LS1 through LS3) were estimated using a Bayesian application of the Gibbs sampler. Data came from Baluchi sheep born between 1966 and 1989 at the Abbasabad sheep breeding station, located northeast of Mashhad, Iran. There were 10,406 records of BWT recorded for all ewe lambs and for ram lambs that later became sires or maternal grandsires. All lambs that later became dams had records of LS1 through LS3. Separate bivariate analyses were done for each combination of BWT and one of the three variables LS1 through LS3. The Gibbs sampler with data augmentation was used to draw samples from the marginal posterior distribution for sire, maternal grandsire, and residual variances and the covariance between the sire and maternal grandsire for BWT, variances for the sire and residual variances for the litter size traits, and the covariances between sire effects for different trait combinations, sire and maternal grandsire effects for different combinations of BWT and LS1 through LS3, and the residual covariations between traits. Although most of the densities of estimates were slightly skewed, they seemed to fit the normal distribution well, because the mean, mode, and median were similar. Direct and maternal heritabilities for BWT were relatively high with marginal posterior modes of .14 and .13, respectively. The average of the three direct-maternal genetic correlation estimates for BWT was low, .10, but had a high standard deviation. Heritability increased from LS1 to LS3 and was relatively high, .29 to .37. Direct genetic correlations between BWT and LS1 and between BWT and LS3 were negative, -.32 and -.43, respectively. Otherwise, the same correlation between BWT and LS2 was positive and low, .06. Genetic correlations between maternal effects for BWT and direct effects for LS1 through LS3 were all highly negative and consistent for all parities, circa -.75. Environmental correlations between BWT and LS1 through LS3 were relatively low and ranged from .18 to .29 and had high standard errors.     

Relationships between longevity,lifetime productivity,carcass traits and conformation in Polish maternal pig breeds

The objective of this study was to obtain heritability estimates for longevity (length of life, length of productive life, number of litters) and lifetime productivity traits (lifetime pig production, lifetime pig efficiency, lifetime litter efficiency) and genetic correlation between them and litter size at first farrowing, growth (ADG), backfat thickness (BF), loin depth, lean meat percentage (LMP), phenotypic selection index (PSI), and exterior in 19423 Polish Landrace (L) and 16049 Polish Large White (LW) sows. Heritabilities for longevity and lifetime productivity traits were 0.10–0.13 for L sows and 0.09–0.11 for LW sows depending on the trait definition. The genetic correlations among these traits were all high and positive, ranging from 0.76 to 0.99. Antagonistic genetic correlations (?0.21 to ?0.26) were found between longevity traits and PSI and LMP in LW sows, while in L sows the respective parameters were lower and not significant for length of productive life. The number of live‐born piglets in the first litter was positively correlated with lifetime pig production and lifetime pig efficiency in both breeds. The genetic correlations of longevity and lifetime pig production with ADG, BF, loin depth and exterior were small, and in most cases, not significant.     

Selection for ovulation rate in rabbits: genetic parameters and correlated responses on survival rates

The aim of this work was to evaluate the correlated responses on survival rates after 10 generations of selection for ovulation rate (OR). Selection was based on the phenotypic value of ovulation rate estimated at d 12 of second gestation by laparoscopy. Traits recorded were litter size (LS), estimated as total number of rabbits born per litter in up to 5 parities; OR, estimated as the number of corpora lutea in both ovaries; the number of implanted embryos (IE), estimated as the number of implantation sites; the number of right and left IE (RIE and LIE); ovulatory difference (OD), defined as the difference between the right and the left OR, expressed as an absolute value; implantatory difference (ID), defined as the difference between RIE and LIE, expressed as an absolute value; embryonic survival (ES), calculated as IE/OR; fetal survival (FS), calculated as LS/IE; prenatal survival (PS), calculated as LS/OR. A total of 1,081 records were used to analyze ES, and 770 were used to analyze FS and PS. The number of records used to analyze the other traits ranged from 1,079 for ID to 3,031 for LS. Data were analyzed using Bayesian methodology. Genetic parameters of OR, OD, and LS were estimated in a previous paper. Estimated heritabilities of IE, ID, ES, FS, and PS were 0.11, 0.03, 0.09, 0.24, and 0.14, respectively. Estimated repeatabilities of IE, ID, and ES were 0.22, 0.12, and 0.20. Estimated phenotypic correlations of OR with ES, FS, and PS were -0.07, -0.26, and -0.28, respectively. Their estimated genetic correlations with FS and PS were negative (probability of being negative 1.00 and 0.98, respectively). Nothing can be said about the sign of the genetic correlation between OR and ES. Ovulation rate was phenotypically uncorrelated with ID. Their estimated genetic correlation was positive (probability of being positive 0.91). The genetic correlation of ID with PS and LS was not accurately estimated. Phenotypic and genetic correlations between LS and survival rates were positive (probability of being positive 1.00). In 10 generations of selection, FS decreased around 1% per generation. No correlated response in ES was observed. In summary, the decrease in FS in rabbits selected for OR seemed to be responsible for the lack of correlated response observed in LS.     

Genetic parameters for body weight, reproduction, and parasite resistance traits in the Creole goat

We estimated the genetic parameters for BW, reproduction, and parasite resistance traits to implement a breeding program for the Creole goat. The traits were preweaning BW at 70 d of age (BW70d), BW at 11 mo of age (BW11), fecal egg count at 11 mo of age (FEC11) for all animals, packed cell volumes of lactating does (PCV), and their fertility (FER) and litter size (LS). We analyzed about 30 yr of data, which included 18,450 records on 11,970 animals from the INRA experimental flock in Guadeloupe (French West Indies). Heritability estimates were low for reproduction traits (0.11 ± 0.02 for LS and FER) to moderate for production traits (0.32 ± 0.03 for BW11; 0.20 ± 0.03 and 0.08 ± 0.02 for the direct and maternal heritability estimates of BW70d, respectively). Heritability estimates for gastrointestinal nematode resistance traits were situated in an intermediate range (0.13 ± 0.05 for PCV and 0.18 ± 0.04 for FEC11). Genetic correlations between FER, PCV, BW11, and the maternal effect of BW70d were altogether positive, whereas LS and FEC11 were almost uncorrelated phenotypically and genetically. These correlations are very favorable for setting up a breeding program, making it possible to improve BW, reproduction, and parasite resistance traits simultaneously.     

Genetic analysis of protein yield,udder health,and female fertility in first-parity Danish Holstein cows

Abstract

Genetic parameters for protein yield, clinical mastitis, SCS, number of inseminations (NI), and days from first to last insemination (FLI) were estimated for first-parity Danish Holstein cows. The objective was to estimate genetic correlations between the five traits mentioned above and to study whether NI and FLI are measures of the same trait. Records containing information on approximately 200 000 cows were analysed using tri-variate animal models. The genetic correlations between the udder health traits and the fertility traits were favourable and in the range from 0.17 to 0.42, whereas the genetic correlations between protein yield and the fertility traits were unfavourable and ranged from 0.43 to 0.52. These results highlight the importance of continuing to emphasize functional traits in future breeding programmes. The genetic correlation between the fertility traits was 0.82. Based on this result, it cannot be concluded that NI and FLI are measures of the same trait.     

Genetic parameters in Finnish blue fox population: Pelt character and live animal grading traits

Abstract

Finnish blue fox farmers breed for increased litter size and pelt size, and improved fur quality. Some farmers select pelt size and fur quality indirectly using live animal evaluations (grading traits). In order to be able to define breeding goals properly, heritabilities and genetic correlations were estimated for size traits and fur quality traits. There were four pelt character traits (pelt size, pelt colour darkness, pelt colour clarity and pelt quality) measured on dried skins, and six grading traits (animal size, grading colour darkness, grading colour clarity, underfur density, guard hair coverage and grading quality). The data included 54,680 animals born during the years 1987–2002, originating from seven farms. The heritabilities were high for pelt colour darkness and grading colour darkness, moderate for pelt size and low for other traits. In general, heritability of a pelt character trait was higher than its corresponding grading trait. Genetic correlations within the pelt character traits were low (～0.11) and within the grading traits mainly moderate or high (～0.44). There was high genetic correlation between pelt darkness and grading darkness, pelt quality and grading density, pelt size and animal size; between pelt quality and grading quality and between pelt colour darkness and grading guard hair coverage. This suggests that selection of pelt character traits via grading traits in most cases is relatively effective.     

Estimation of direct and maternal genetic parameters for growth and carcass traits in a herd of Japanese Black cattle in Miyagi prefecture, using a multitrait animal model

Data from 1170 records of fattening calves were collected on growth and carcass traits from a Japanese Black cattle herd located in Miyagi prefecture, Japan. The objective was to determine direct and maternal heritabilities, direct and maternal genetic correlations and phenotypic correlations between bodyweight at the beginning of the fattening period (BWS), bodyweight at the end of the fattening period (BWF), carcass weight (CW), average daily gain during the fattening period (ADG), rib eye area (REA), rib thickness, subcutaneous backfat thickness (SFT), yield estimate (YE) and beef marbling score (BMS). Direct heritability estimates of 0.16 (SFT) and 0.07 (BMS) were low, whereas estimates of the other traits were medium to high and ranged between 0.44 (REA) and 0.78 (CW). Direct genetic correlations were all positive, except those that were between BWS and SFT, and between BWS and YE (?0.49 and ?0.14, respectively). The lowest positive genetic correlation was between BWS and BMS (0.04) and the highest was between BWF and CW (0.99). The phenotypic correlation coefficients ranged between ?0.41 (between SFT and YE) and 0.96 (between BWF and CW). Maternal heritability estimates were generally low and ranged between 0.00 for BMS and 0.08 for BWS, CW and ADG. Selection programs comprising information on growth and carcass traits of calves and maternal traits of dams were suggested.     

Udder health and female fertility traits are favourably correlated and support each other in multi-trait evaluations

Genetic parameters were estimated for protein yield (PY), clinical mastitis (CM), somatic cell score, number of inseminations (NI) and days from calving to first insemination (CFI) in first‐parity Swedish Red cows by series of tri‐variate linear animal models. The heritability of PY was moderate (0.34 ± 0.004), and the heritabilities of the functional traits were all low (0.014 ± 0.001–0.14 ± 0.004). The genetic correlation between CM and CFI (0.38 ± 0.05) was stronger than the correlation between CM and NI (0.05 ± 0.06), perhaps because CM and CFI usually are observed in early lactation when the cow is likely to be in negative energy balance, whereas NI generally is recorded when the cow is not in negative energy balance any more. The genetic correlation between NI and CFI was very close to zero (?0.002 ± 0.05), indicating that these two fertility traits have different genetic backgrounds. All genetic correlations between PY and the functional traits were moderate and unfavourable, ranging from 0.22 ± 0.02 to 0.47 ± 0.03. In addition, the effect of including genetic and phenotypic correlations between the trait groups milk production, udder health and female fertility on the accuracy of the selection index was quantified for a heifer, a cow and a proven bull. The difference between the accuracy obtained by multi‐trait and single‐trait evaluations was largest for the cow (0.012) and small for the heifer and the bull (0.006 and 0.004) because the phenotype of the cow for one trait could assist in predicting the Mendelian sampling term for a correlated trait.     

Genetic study on pelt quality traits in the Gotland sheep breed

Abstract

Genetic parameters were estimated for pelt quality traits of the Gotland sheep breed using data from the Swedish Sheep Recording Scheme and multiple-trait animal models. Data on detailed pelt quality traits were available for 51,455 lambs born from 1991 to 2003. For 4,771 lambs there also was information about a subjectively measured overall score for pelt quality. Sex of lamb, age of ewe, litter size, age of lamb, and interactions between these had significant effects on pelt quality. Heritabilities were moderately high (0.20 to 0.48) and genetic correlations between the traits were low to highly positive (?0.18 to 0.95). Breeding for an increased overall score will in the short term improve score for quality of hair, score for curl, and score for nuance of colour. Size of curl and score for thickness of fleece may also increase and this is not always advantageous as these are traits with optimum values.     

Genetic correlations for foal and studbook traits with racing traits and implications for selection strategies in the Finnhorse and Standardbred trotter

Genetic correlations for body measurements and conformation and functional traits in foals and studbook horses with racing traits were estimated in the Finnhorse and Standardbred. Genetic response and accuracy were estimated using records of animal, half‐sibs and parents in selection scenarios for racing traits, for foal and racing traits, for studbook and racing traits, and using records of animal, half‐sibs and parents for foal traits and racing traits of parents. Racing time and earnings were the breeding objective. Low‐to‐moderate genetic correlations for body measurements and racing traits indicated that selection favours bigger horses at all ages. Being mainly favourable for the breeding objective, genetic correlations for conformation and functional traits with racing traits were highest for the foal traits of type, trot and overall grade and for the studbook traits of character and movements. Genetic correlations for foal and studbook conformation with racing traits were low in the Finnhorse and moderate to high in the Standardbred. In foals, the highest genetic correlations were for trot with racing time (?0.54) and with earnings (0.52) in the Finnhorse, and for overall grade with racing time (?0.54) and with earnings (0.54) in the Standardbred. In studbook horses, genetic correlations were high for character with racing time and earnings in the Finnhorse (?0.68, 0.61) and in the Standardbred (?0.63, 0.70), and for movements with racing time and earnings in the Finnhorse (?0.70, 0.69) and in the Standardbred (?0.90, 0.88). To increase accuracy of conformation and functional traits, foal traits would be more useful in the index with racing traits, as being less preselected than studbook traits. The foal traits (type, trot, overall grade) having moderate heritability and genetic correlations with racing traits would be useful in multi‐trait index before a racing career, where the greatest gain is because of a shorter generation interval. It would be feasible to implement for AI stallions.     

河北省西门塔尔牛体重体尺性状遗传参数分析

［目的］本研究旨在探究河北省西门塔尔牛体重和体尺性状的遗传参数,为育种提供参考。［方法］本研究以2015～2021年河北天和肉牛养殖有限公司266头西门塔尔牛的体重体尺性状为研究材料,包括体重性状及体高、十字部高、体斜长、胸围、腹围和管围等6个体尺性状,使用DMU软件采用AI-REML结合EM算法并配合动物模型对体重、体尺性状进行了遗传参数估计。［结果］结果表明：体重、体高、十字部高、体斜长、胸围、腹围和管围的遗传力分别为0.41、0.41、0.45、0.45、0.48、0.31和0.66。体重与体尺之间的遗传相关范围为0.20（体高）~0.79（胸围）,表型相关范围为0.14（十字部高）~0.23（胸围）;体尺性状间的遗传相关范围为-0.70（腹围和管围）~0.92（体高和十字部高）,表型相关范围为-0.10（腹围和管围）~0.94（体高和十字部高）。［结论］体重与体尺性状均属于高遗传力性状,体重及体尺性状间除管围外其他体尺性状间均呈较强的遗传正相关,在选育过程中加强对这些性状的选育,有利于提高西门塔尔牛的生长发育性能。     

Genetic and phenotypic parameters for conformation and yield traits in three Swiss dairy cattle breeds

This study presents genetic parameters for conformation traits and their genetic and phenotypic correlations with milk production traits and somatic cell score (SCS) in three Swiss dairy cattle breeds. Data on first lactations from Holstein (67 839), Brown Swiss (173 372) and Red & White breeds (53 784) were available. Analysed conformation traits were stature and heart girth (both in cm), and linear scores of body depth, rump width, dairy character or muscularity, and body condition score (only in Holstein). A sire model, with relationships among sires, was used for all breeds and traits and variance components were estimated using AS‐REML. Heritabilities for stature were high (0.6–0.8), and for the linear type traits ranged from 0.3 to 0.5, for all breeds. Genetic correlations with production traits (milk, fat and protein yield) and SCS differed between the dairy breeds. Most markedly, stronger correlations were found between SCS and some conformation traits in Brown Swiss and Red & White, indicating that a focus on a larger and more ‘dairy’ type in these breeds would lead to increased SCS. Another marked difference was that rump width correlated positively with milk yield traits in Holstein and Red & White, but negative in Brown Swiss. Results indicate that conformation traits generally can be used as predictors for various purposes in dairy cattle breeding, but may require specific adaptation for each breed.     

Genetic associations of visual scores with subsequent rebreeding and days to first calving in Nellore cattle

Records of Nellore animals born from 1990 to 2006 were used to estimate genetic correlations of visual scores at yearling (conformation, C; finishing precocity, P; and muscling, M) with primiparous subsequent rebreeding (SR) and days to first calving (DC), because the magnitude of these associations is still unknown. Genetic parameters were estimated by multiple‐traits Bayesian analysis, using a nonlinear (threshold) animal models for visual scores and SR and a linear animal models for weaning weight (WW) and DC. WW was included in the analysis to account for the effects of sequential selection. The posterior means of heritabilities estimated for C, P, M, SR and DC were 0.24 ± 0.01, 0.31 ± 0.01, 0.30 ± 0.01, 0.18 ± 0.02 and 0.06 ± 0.02, respectively. The posterior means of genetic correlations estimated between SR and visual scores were low and positive, with values of 0.09 ± 0.02 (C), 0.19 ± 0.03 (P) and 0.18 ± 0.05 (M). On the other hand, negative genetic correlations were found between DC and C (?0.11 ± 0.09), P (?0.19 ± 0.09) and M (?0.16 ± 0.09). The primiparous rebreeding trait has genetic variability in Nellore cattle. The genetic correlations between visual scores, and SR and DC were low and favourable. The genetic changes in C, P and M were 0.02, 0.03 and 0.03/year, respectively. For SR and DC, genetic trends were 0.01/year and ?0.01 days/year, respectively, indicating that the increase in genetic merit for reproductive traits was small over time. Direct selection for visual scores together with female reproductive traits is recommended to increase the fertility of beef cows.     

Genetic parameters of production and fertility traits in Hungarian Merino sheep

Hungary has a long-standing tradition in Merino breeding and improvement. During the past decades several attempts have been made to introduce a number of other sheep breeds. Although this effort was not in vain the majority of the sheep population is still the Hungarian Merino breed. The adaptability, endurance and excellent wool-producing ability of this breed is first rate and is worth preserving (V eress et al. 1997). The profitability of a sheep production system is determined by both fertility and production traits. Reproduction performance is usually defined as litter weight per dam per year. Progress can be achieved through various ways. One of them is frequent lambing which also has the advantage that lamb production becomes more consistent throughout the year. Another possibility is producing larger litter sizes (LS), and yet a another opportunity for increased production is having lambs with larger weights (WT). Simultaneous enhancement can also be achieved if there is no antagonism between these traits. From these several fertility traits LS from the first to the fifth parity was chosen for analysis as LS is one of the most important traits concerning reproduction performance. Of the production traits, WT measured at various ages, greasy fleece weight (GFW) from the first five shearings, staple length (SL) and fibre diameter (FD) at the age of 1 year were taken into the analysis. According to other studies there are several factors influencing the above mentioned traits, namely age, season of previous lambing (PLS), type of birth (TOB), and sex. In general, LS increased with advancing age (L ong et al. 1989; B unge et al. 1990; A p D ewi et al. 1996). For GFW the peak of production was achieved in a relatively early age of 3 years, reported by V eress (1969) and by T urner and Y oung (1969). The effect of PLS on LS was that smaller litters were observed with previous lambing seasons of summer and autumn (L ong et al. 1989). TOB and sex effect on WT have been investigated by several authors (T urner and Y oung 1969, p. 46, 51.; S hrestha and H eaney 1985; M avrogenis 1988; B unge et al. 1990; J urado et al. 1994; V eress et al. 1995; S hrestha et al. 1996). Single-born lambs are heavier than multiples although this difference decreases with age. All authors also agree that male lambs are heavier than females. TOB and sex effect on GFW were reported by T urner and Y oung (1969). T urner and Y oung labelled the TOB effect as a ‘maternal handicap’ as the effect is noticeable even in maturity but decreasing by age. T urner and Y oung (1969) also observed that the WT and GFW of male animals exceeds that of the females, but, unlike with the previous effect, the difference increases with age. There was a negligible difference between sexes in SL and FD. Studying the results of numerous authors, estimates of the genetic parameters of LS, WT, GFW, SL, and FD were found to be generally consistent. Heritabilities of LS ranged from 0.05 to 0.08 (A l -S horepy and N otter 1996; A p D ewi et al. 1996; for litter size at first parity only). A p D ewi et al. (1996) found very high (>0.9) genetic correlations between the first and adult litter size. Heritabilities estimated for WT were higher than those of the fertility traits and ranged in the interval of 0.05–0.47 (S hrestha and H eaney 1985; L ong et al. 1989; B unge et al. 1990; K umar and R eheja 1993; J urado et al. 1994; A l -S horepy and N otter 1996). Genetic correlations between yearling and adult WT were high (J urado et al. 1994; 0.85; A l -S horepy and N otter 1996; 0.85–1.0). GFW heritabilities reported by B lair et al. (1985); T urner and Y oung (1969) were about 0.2 thus also exceeding those of the fertility traits. Regarding the genetic parameters of SL & FD, N otter and H ough (1997); M orris et al. (1996) reported that the heritability of SL and FD was higher than that of GFW (026–0.34; 0.47–0.58). Genetic correlations among production traits were mainly low (M orris et al. 1996; and T urner and Y oung 1969). The objectives of this paper were to determine whether the characteristics of the Hungarian Merino sheep population correspond with the features given in the literature review. Thus the objectives were to obtain the factors influencing the traits examined and to estimate genetic parameters of LS, WT, GFW, SL, and FD, respectively.     

Shoulder ulcers in sows are genetically correlated to leanness of young pigs and to litter weight

Abstract

The aim of this study was to estimate the heritability for shoulder ulcers (SU) and sows' body condition at weaning (BCw), and the genetic correlations between these traits and some production and reproduction traits included in the current breeding goal of sow lines. The analyses were based on data on Swedish purebred Yorkshire from nucleus as well as multiplier herds. The estimated heritabilities were for BCw 0.21, and for SU 0.13. Significant genetic correlations were found between sidefat thickness (at 100 kg) and BCw (thicker fat layer at 100 kg – better condition at weaning), between sidefat thickness and SU (thicker fat layer – less SU), between litter weight at 3 weeks and BCw (heavier litter – lower body condition) and between litter weight at 3 weeks and SU (heavier litter – more SU). The genetic correlation between BCw and SU was also significant (lower body condition – more SU).     

Genetic (co)variance components for ewe productivity traits in Katahdin sheep

The objective of this study was to estimate genetic parameters, in Katahdin sheep, for total weight of litter weaned per ewe lambing (TW) and its components, number of lambs born (NB), number of lambs weaned (NW), and average weight of lambs weaned (AW) measured as traits of the ewe. Weaning weights of lambs (WW) were adjusted to 60 d of age and for effects of ewe age, lamb sex, and type of birth and rearing and averaged over all lambs in the litter to obtain AW. The 60-d age-adjusted WW were adjusted for ewe age and lamb sex and summed over all lambs in the litter to obtain TW. A total of 2,995 NB and NW records, 2,622 AW, and 2,714 TW records were available from 1,549 ewes (progeny of 235 sires) over 4 yr. Heritabilities were initially estimated for each trait from univariate REML analyses. Estimates of genetic correlations were obtained from bi- and trivariate analyses. Models for NB, NW, AW, and TW included random ewe additive and permanent environmental effects. A random service sire effect was also fit for AW and TW. Heritabilities of TW, NB, NW, and AW from univariate analyses were 0.12, 0.12, 0.09, and 0.13 (all P < 0.01), respectively. Permanent environmental effects were significant (P < 0.01) for TW and AW. Genetic correlations of TW with NB, NW, and AW ranged from 0.27 to 0.33, 0.88 to 0.91, and 0.72 to 0.76, respectively; those of NB with NW and AW ranged from 0.70 to 0.75 and -0.01 to 0.02, respectively; and that between NW and AW ranged from 0.40 to 0.55. Genetic parameters were also obtained for lamb survival to weaning (LS) and WW measured as traits of the lamb, and the relationships between WW of the ewe as a lamb and her subsequent records for NB and NW were also estimated. A total of 5,107 LS and 5,444 WW records were available. Models for WW and LS included random animal and maternal genetic, maternal permanent environmental, and litter effects. Heritability of WW ranged from 0.15 to 0.20. There was no evidence of genetic effects on LS. Direct genetic correlations of WW with NB and NW were not significantly different from zero. The correlation between maternal genetic effects on WW, and animal genetic effects on NW, averaged 0.35. Results of this study indicate that there are no major antagonisms among TW and its components, so that selection for TW would not have adverse effects on any component traits and vice versa. Maternally superior ewes for WW appear to also be somewhat superior for NW.