Total Litter Weight Research Articles

A comparative study of the reproductive traits and clustering analysis among different pig breeds

The data were from 149 pigs from seven pig genetic groups raised in «Tavriys'ki Svyni» Ltd (Kherson region, Ukraine). The following genetic groups were included in our analyses: LW × LW (n = 19), LW × LN (n = 43), LW × PT (n = 13), LN × LN (n = 15), UM × LN (n = 23), UM × PT (n = 17) and UM×UM (n = 16). The objective this work was evaluation of animal reproductive traits using multivariate analysis. Variables measured and derived included total no. piglets born (TNB), no. piglets born alive (NBA), freq. of stillborn piglets (FSB), total litter birth weight (TLBW), average piglet birth weight (APBW), pre-weaning mortality in piglets (PWM), no. weaned piglets (NW), total weaning weight of litter (TWWL) and average piglet weaning weight (APWW). After standardization, multivariate analyses (Cluster analysis and Principal Component Analysis) were carried out using STATISTICA (StatSoft Ltd.) to place pig interbreeding combinations in groups in accordance with their degree of similarity and verify discriminatory capacity of the original traits in the formation of these groups. The tree diagram showed clear distances between the pig genetic groups studied. In the tree diagram obtained from the analysis of the distances between interbreeding combinations, two distinct groups (clusters) were seen, one with UM × LN and UM × UM animals, and the other with the rest of the pig genetic groups in the study. The eigenvalues for the first two Principal Components (PC1 and PC2) together accounted for near 65% of the variance of the pig’s reproductive traits. The first principal component (PC1) explained 34.9% total variation. It was represented by significant positive loadings for TNB, NBA and TLBW. The second principal component (PC2) accounted for an additional 29.7% of the generalized variance and was represented by significant loadings for NW, TWWL and APWW. Thus, PC1 defined no. piglets and total litter birth weight, while PC2 represented no. weaned piglets and total weaning weight of litter. In conclusion, the multivariate methods (Cluster Analysis and PCA) has been proven to be a very effective method to obtain a synthetic judgment of reproductive traits in pig.

PIG PRODUCTIVITY UNDER PURE BREEDING AND CROSSBREEDING

For the research the groups were formed by method of analogues based on origin, age, physiological state, live weight. Studying sperm productivity, the number of ejaculates obtained during the year, average volume, concentration, and the total number of spermatozoa in the ejaculate were taken into account and conducted according to conventional techniques using a digital photometer “SDM-30” produced by "Minitüb”. Indicators of economical useful traits of the test animals were calculated according to primary zoo-technical accounting by standard methods of biometric analysis. To determine breeding value of animals by the BLUP method, software developed at the Institute of Pig Breeding "System determining the breeding value of pigs" was used. In carrying out the work, population genetics and mathematical methods were applied for studying of patterns of variability, repeatability, assessment of the genotype of animals.
 Reproductive quality of the sows was assessed by multiparity (total number of piglets at farrowing), prolificacy (piglet’s weight at birth, kg), milk ability (total weight of litter at 21 days, kg) piglet’s weight at weaning and survival of offspring to weaning. Survival of piglets, homogeneity and uniformity of litter were determined by modified M. D. Berezovsky – D. V. Lomako index and V. P. Kovalenko homogeneity index. Growth and development were controlled by change of individual live weight via weighing. Average daily gain was determined based on the initial and final live weight and number of days between weightings.
 Dynamics of indicators of growth and development, maternal qualities of sows and sperm productivity and fertility of boars at the purebred animal of initial breeds and live weight and age at 100 kg in the hybrids of first generation were studied. The youngsters obtained at crossbreeding Large White breed of domestic and foreign selection with Landrace had the best indicators of growth and development than the purebred counterparts in all age periods. Higher live weight at weaning at age of 60 days was typical for combination ♀LWE x ♂LE and ♀LE x ♂LWE; it is quite natural, because they had lower average number of piglets at weaning. For maturing volumes of back of the carcass and a well-developed layer of fat should be adjusted to Landrace sows and Large White boars. Fattening of commercial hybrids obtained by this scheme under Ukrainian conditions is advisable to check out at animal’s live weight of 115 ... 120 kg.
 Significant correlations were proven on the basis of: BLUP index – back fat thickness at the level of the 6-7 thoracic vertebra – -0,221 ± 0,0938 (tr = 2,35), BLUP index – back fat thickness on sacrum – -0,298 ± 0,0898 (tr = 3,31), BLUP index – back fat thickness at the midpoint of the back between the withers and sacrum – -0,239 ± 0,0929 (tr = 2,57), BLUP index – body length – -0,338 ± 0,0873 (tr = 3, 86), BLUP index – multiparity – -0,294 ± 0,0900 (tr = 3,26), BLUP index – total weight of the litter at the date of weaning – -0,233 ± 0,0932 (tr = 2,49). Keeping the selection process towards selection and combination of parental pairs by BLUP method is one of the ways to increase the productive capacity of the animals.
 According to the research it was found that asymmetry of testes sizes was observed together with individual peculiarities of testes form at the same breeding boars. Testes have physiological asymmetry. Ratio of areas of the left testes to right was Sl/Sr = 1.04, and volumes respectively Vl/Vr = 1.20, on average, left testes by their areas were 2.7% more than the right, and by volumes – 14.6% respectively.
 Comparing the live weight of boars with weight of their testes does not have a logical pattern. The average weight of testes was 0.14% of the live weight of breeding boars. Total volume of ejaculate on a group of boars was 355,3 ± 16,9 ml. The concentration of sperm in the ejaculate was 64,2 ± 4,6 billion, activity – 8,7 ± 0,2 points. The studies found that boars with greater weight of testes produce sperm with more sperm concentration and that's why more sperms in the ejaculate were obtained from them.
 Combination of Landrace and Large White breeds is apposite for obtaining precocious pigs with well-developed layer of fat at the 6-7 thoracic vertebra and high level of prolificacy (1,8-1,9 kg).

Estimation of the variance due to parent-of-origin effects for productive and reproductive traits in Lori-Bakhtiari sheep

Parent-of-origin effects are often excluded from models used for estimating of additive and non-additive genetic variances. Omission of parentally-linked genetic factors, such as imprinting, from statistical models has potential to induce profound bias during the estimation. In this study, parent of origin variance for productive and reproductive traits in Lori-Bakhtiari sheep was estimated using a gametic relationship matrix approach. The data set were obtained from a total of 7568 animals, collected from 1994 to 2012 from the Lori-Bakhtiari research flock at Shooli station in Shahrekord, Iran. Growth traits were included birth weight (BWT), weaning weight (WWT), 6-month weight (WT6), 9-month weight (WT9), yearling weight (WT12), average daily gain from birth to weaning (ADGa), and from weaning to 6-month (ADGb). In addition, litter size at birth (LSB), litter size at weaning (LSW), litter mean weight per lamb born (LMWLB), and litter mean weight per lamb weaned (LMWLW) were analyzed as basic reproductive traits, and total litter weight at birth per ewe lambing (TLWB) and total litter weight at weaning per ewe lambing (TLWW) as composite reproductive traits. Models including or excluding maternal and paternal imprinting effects were compared using the ayesian information criterion (BIC). For all growth traits, except WT6 and WT12, adding maternal imprinting effects into the models decreased BIC, with estimates ranging from 10.5% (WWT) to 23.3% (BWT) of the total phenotypic variance. Paternal imprinting effects, in the other hand, was estimated as 6.9% of the total phenotypic variance for ADGb. For reproductive traits, maternal imprinting effects explained up to 6% of total phenotypic variance for TLWW. Adding paternal or maternal imprinting to the models decreased the direct additive genetic, maternal additive genetic and maternal permanent environmental variance for the growth traits.

Selection for female traits of high fertility affects male reproductive performance and alters the testicular transcriptional profile

BackgroundMany genes important for reproductive performance are shared by both sexes. However, fecundity indices are primarily based on female parameters such as litter size. We examined a fertility mouse line (FL2), which has a considerably increased number of offspring and a total litter weight of 180% compared to a randomly bred control line (Ctrl) after more than 170 generations of breeding. In the present study, we investigated whether there might be a parallel evolution in males after more than 40 years of breeding in this outbred mouse model.ResultsMales of the fertility mouse line FL2 showed reduced sperm motility performance in a 5 h thermal stress experiment and reduced birth rate in the outbred mouse line. Transcriptional analysis of the FL2 testis showed the differential expression of genes associated with steroid metabolic processes (Cyp1b1, Cyp19a1, Hsd3b6, and Cyp21a1) and female fecundity (Gdf9), accompanied by 150% elevated serum progesterone levels in the FL2 males. Cluster analysis revealed the downregulation of genes of the kallikrein-related peptidases (KLK) cluster located on chromosome 7 in addition to alterations in gene expression with serine peptidase activity, e.g., angiotensinogen (Agt), of the renin-angiotensin system essential for ovulation. Although a majority of functional annotations map to female reproduction and ovulation, these genes are differentially expressed in FL2 testis.ConclusionsThese data indicate that selection for primary female traits of increased litter size not only affects sperm characteristics but also manifests as transcriptional alterations of the male side likely with direct long-term consequences for the reproductive performance of the mouse line.

Inbreeding effects on some reproductive traits in Markhoz goats

The objective of this study was to estimate the inbreeding coefficient and its effects on reproductive traits in Markhoz goats. The pedigree file included 5351 kids produced by 234 bucks and 1470 does. Average inbreeding coefficient for the whole population was 2.68%, and the minimum and maximum inbreeding coefficients were 0.05% and 31.25%, respectively. Average coefficient of inbreeding for inbred population was 5.17% and the number of inbred animals in the population was 2777. For investigating effects of inbreeding coefficient on reproductive traits, 3443 records were available for litter size at birth (LSB), litter size at weaning (LSW), total litter weight at birth (TLWB) and mean of litter weight at birth (MLWB). Furthermore, available records for total litter weight at weaning (TLWW) and mean of litter weight at weaning (MLWW) were 2918. Inbreeding depression was estimated as the linear regression of performance on the individual inbreeding coefficient of kids and dams using the most appropriate animal model based on Akaike’s information criterion. Furthermore, inbreeding depressions for LSB and LSW were estimated using threshold and Poisson models. Regression coefficients of LSB, LSW, TLWB, TLWW, MLWB and MLWW on inbreeding coefficient of kids were –0.035, –0.019, –0.077 kg, –0.782 kg, –0.009 kg and –0.332 kg, respectively. Furthermore, regression coefficients of LSB, LSW, TLWB, TLWW, MLWB and MLWW on inbreeding coefficient of dams were 0.064, –0.013, 0.241 kg, 0.638 kg, 0.028 kg and –1.783 kg, respectively. The obtained results from this study showed that inbreeding depression is controlled by an appropriate mating system policy.

Effects of age and nutritional status at mating on the reproductive and productive traits in Suffolk sheep kept under permanent outdoor management system

This study examined the variability of reproductive and productive traits in Suffolk sheep (a commercial flock, n = 316 ewes) with regard to the dams’ age or the nutritional status of sheep at mating under a year-round outdoor management. Data were collected across a 3-year monitoring period (totally 655 observations). The fixed effects of dam’s age (dams grouped as: 2, 3, 4, 5, 6 years and older), ewe’s live weight (LW; ewes grouped as: < 72 kg; 72–83 kg; > 83 kg), and backfat thickness at mating (BT; ewes grouped as: < 7.9 mm; 7.9–10.5 mm; > 10.5 mm) were evaluated. The dam’s age influenced reproductive and productive traits such that 2- and 6-year and older ewes reached the lowest values. Ewes with LW > 83 kg had significantly higher lambing rate (11.8%) compared to those with LW < 72 kg. The group of ewes with LW < 72 kg gave birth to a significantly lower number of live lambs in litter (–8.9%) in comparison with LW < 83 kg group. An increase (9.9%; P < 0.01) of total litter weight at birth or an increase (12.5%; P < 0.05) of total litter weight at 100 days of age were detected in LW > 83 kg group compared to LW < 72 kg group. BT > 10.5 mm ewes had by 8.9% lower lambing rate (P < 0.05), by 6.8% lower litter size (P < 0.05), by 14.5% lower number of live lambs in litter (P < 0.01), and by 8.6% lower total litter weight at birth compared to BT < 7.9 mm ewes. A significantly lower total litter weight at 100 days of age (–10.8%) and a significantly lower total litter gain from birth to 100 days of age (–11.5%) were detected in BT > 10.5 mm ewes in comparison to BT 7.9–10.5 mm ewes.

The potential interaction between ewe body condition score and nutrition during very late pregnancy and lactation on the performance of twin-bearing ewes and their lambs.

ObjectiveThe present study aimed to determine the impact of ewe body condition score (BCS) (over a range of 2.0 to 3.0) and nutritional treatments (consisting of differing herbage masses) during very late pregnancy and lactation and their potential interaction on the performance of twin-bearing ewes and their lambs to weaning.MethodsOn day 142 of pregnancy, twin-bearing ewes with a BCS of 2.0, 2.5, or 3.0 were allocated to a “Moderate’ or ‘Unrestricted’ nutritional treatment until day 95 of lactation (weaning). The nutritional treatments aimed to achieve average herbage masses of 1,200 to 1,300 kg dry matter (DM)/ha (Moderate) and 1,500 to 1,800 kg DM/ha (Unrestricted).ResultsThere were no three-way interactions between ewe BCS group, nutritional treatment and time for any ewe or lamb parameter. The nutritional treatments had no effect (p>0.05) on lamb birth or weaning weight. Lambs born to Moderate ewes had greater survival and total litter weight at weaning (p<0.05). Regardless of BCS group, Unrestricted treatment ewes had greater body condition and back-fat depth at weaning than Moderate treatment ewes (p<0.05). Ewes of BCS 2.0 group reared lighter lambs to weaning (p<0.05) and tended to have a lower total litter weight (p = 0.06) than BCS 3.0 group ewes.ConclusionThis study suggests farmers should aim to have all ewes with a BCS of 2.5 or 3 in late pregnancy for optimal lamb weaning performance. Furthermore, there is no benefit to lamb production of offering ewes pasture masses >1,200 kg DM/ha during very late pregnancy and lactation.

Genetic Parameters and Genetic Trends for Reproductive Traits of Santa Ines Sheep Kept in Extensive Environments in Brazil

Studying the Santa Ines sheep breed is important, as it is the most prevalent breed in Brazil and can adapt to many environments. This study included data were collected over a period of 12 years from 33 flocks in 10 Brazilian States. The estimation of variance components, genetic parameters and breeding values were obtained by DFREML method, using lineal mixed model in single-trait analysis. Traits of age at first lambing (AFL), lambing interval (LI), survivability (SU), litter size at birth (LSB), litter size at weaned (LSW),total litter weight at birth (TLWB) and total litter weight at weaning (TLWW) were assessed. The significance of the fixed effects to be included in the model was performed using statistic program R. The effects of breeder and lambing year were significant (P<0.001). A remarkable phenotypic and permanent environmental variability were found in all traits. Direct heritability estimates were 0.13, 0.04, 0.01, 0.12, 0.03, 0.16 and 0.18 for AFL, LI, SU, LSB, LSW, TLWB and TLWW, respectively. The estimated fractions of variance due to the permanent environmental effects in any traits were high magnitude (0.79 to 0.97). The annual genetic gain has a slightly negative trend in all of them except for AFL and SU. Results indicate that change in environmental conditions of flock in addition to the direct selection for TLWB and TLWW, can be used as selection criteria for improving the productivity of this sheep.

Genetic Analysis of Basic and Composite Reproduction Traits in Guilan Sheep

Abstract The objective of the present study was to estimate genetic parameters for reproductive traits in Guilan sheep. Data were comprised of 14,534 records of lambs from 136 sires and 2,021 dams which were collected during 1994 to 2011 by the Agriculture Organization of Guilan Province in the north of Iran. The basic reproductive traits were litter size at birth (LSB), litter size at weaning (LSW), litter mean weight per lamb born (LMWLB), and litter mean weight per lamb weaned (LMWLW). The composite reproductive traits were total litter weight at birth per ewe lambing (TLWB) and total litter weight at weaning per ewe lambing (TLWW). The general linear model procedure of SAS was used for determining the fixed effects which had significant effect on the traits under study. The flock-year-season of lambing had significant effect on studied traits (P&lt;0.01). The genetic parameters were estimated with repeatability animal model using restricted maximum likelihood (REML) procedure of the Wombat program. Direct heritability estimates were 0.00, 0.00, 0.01, 0.01, and 0.03 for LSB, LSW, LMWLW, TLWB, and TLWW, respectively, and corresponding repeatabilities were 0.2, 0.00006, 0.01, 0.972 and 0.034, respectively. Genetic correlation estimates between traits ranged from -0.99 for LSB-LSW to 0.99 for LMWLW-TLWW. Phenotypic correlations ranged from -0.09 for LSB-TLWB to 0.98 for LMWLW-TLWW and environmental correlations ranged from -0.03 for LSW-TLWW to 0.98 for LMWLW-TLWW. The results showed that strong positive genetic correlations of LMWLB and LMWLW with other traits may improve meat production efficiency in Guilan sheep. The low estimates of heritability and repeatability obtained for ewe productivity traits indicate that selection based on the ewe’s own performance may result in slow genetic improvement.

Genetic relationships between boar feed efficiency and sow piglet production, body condition score, and stayability in Norwegian Landrace pigs.

Both feed efficiency and sow production are economically important traits in pig breeding. One challenge in a maternal line such as Norwegian Landrace is to breed for highly feed efficient fattening pigs and, at the same time, produce sows with high daily feed intake to maintain their BCS in multiple parities. The aim of this study was to estimate genetic correlations among novel feed efficiency measurements on Norwegian Landrace boars and piglet production, stayability, and body condition in Norwegian Landrace sows. The feed efficiency measurements were lean meat and fat efficiency. These measurements were calculated using an extended residual feed intake model where total feed intake in the test period was the response variable and fat (kg) and lean meat (kg) on the carcass were included as both fixed and random regressions. The random regression coefficients that resulted from this model were breeding values, which represented the amount of feed used to produce an extra kilogram of lean meat and fat. The sow traits were stayability of the sow from first to second parity, BCS at weaning, litter weight at 3 wk, and total number of piglets born. All traits were recorded on first parity purebred Norwegian Landrace and analyzed using multivariate animal models. All genetic correlations between fat efficiency and sow traits were low. Significant genetic correlations were found only between fat efficiency and stayability (0.21 ± 0.11) and between fat efficiency and total litter weight at 3 wk (0.21 ± 0.10). The results indicate that selection for efficient deposition of fat could give poor stayability and lower litter weight at 3 wk in first parity sows. The genetic correlations between lean meat efficiency and sow traits were not significantly different from 0 and signified no genetic relationships between these traits. Selection for efficient deposition of lean meat should not affect the sow traits and is, therefore, beneficial.

Hritabilities and genetic and phenotypic correlations of litter uniformity and litter size in Large White sows

Litter uniformity, which is usually represented by within-litter weight coefficient of variation at birth (CVB), could influence litter performance of sows and the profitability of pig enterprises. The objective of this study was to characterize CVB and its effect on other reproductive traits in Large White sows. Genetic parameters and genetic correlation of the reproductive traits, including CVB, within-litter weight coefficient of variation at three weeks (CVT), total number born (TNB), number born alive (NBA), number born dead (NBD), gestation length (GL), piglet mortality at birth (M0), piglet mortality at three weeks (M3), total litter weight at birth (TLW0), and total litter weight at three weeks (TLW3) were estimated for 2 032 Large White litters. The effects of parity and classified litter size on CVB, CVT, TNB, NBA, NBD, GL, M0, M3, TLW0, and TLW3 were also estimated. The heritabilities of these reproductive traits ranged from 0.06 to 0.17, with the lowest heritability for CVB and the highest heritability for TLW0. Phenotypic and genetic correlations between these reproductive traits were low to highly positive and negative (ranging from −0.03 to 0.93, and −0.53 to 0.93, respectively). The genetic correlations between TNB and CVB, and between M0 and CVB were 0.32 and 0.29, respectively. In addition, CVB was significantly influenced by parity and litter size class (P<0.05). All the results suggest that piglet uniformity should be maintained in pig production practices and pig breeding programs.

Correlated genetic trends for production and welfare traits in a mouse population divergently selected for birth weight environmental variability

The objective of this work was to study the changes that, selecting for environmental variability of birth weight (BW), could bring to other interesting traits in livestock such as: survivability at weaning (SW), litter size (LS) and weaning weight (WW), their variability assessed from standard deviations of LS, standard deviation of WW (SDWW) and also the total litter weight at birth (TLBW) and total litter weight at weaning. Data were registered after eight generations of a divergent selection experiment for BW environmental variability in mice. Genetic parameters and phenotypic and genetic evolution were assessed using linear homoscedastic and heteroscedastic models in which the traits were attributed to the female, except BW and WW that were in some models also attributed to the pup. Genetic correlation between the trait and variability levels was −0.81 for LS and −0.33 for WW. Clear divergent phenotypic trends were observed between lines for LS, WW and SDWW. Although animals were heavier in the high line, TLBW and at weaning was greater in the low line. Despite the negative genetic correlation that was obtained, SDWW was also higher in the high line. Heritabilities were 0.21 and 0.06, respectively, for LS and SW. Both phenotypic and genetic trends showed clear superiority of the low line over the high line for these traits, but inferior for WW. Heteroscedastic model performed similar to the homoscedastic model when there was enough information. Considering LS and survival, the low line was preferred from a welfare point of view, but its superiority from the productivity perspective was not clear. Robustness seemed higher as shown by a low variation and having a benefit to the animal welfare, but this still remains unclear. It was concluded that low variation benefits the welfare of animals.

Genetic parameter estimates for growth and reproductive traits in Lori sheep

Lori sheep is one of the well adapted and relatively heavy breeds in mountainous regions of Iran, primarily reared for mutton production. The current study was conducted to estimate the (co) variance components and genetic parameters by restricted maximum likelihood method using six univariate models for growth and four univariate models for reproductive traits. Data and pedigree information were collected at Agricultural Organization of Lorestan province, west of Iran from 2001 to 2012. Studied growth traits were birth weight (BW), weaning weight (WW), 6-month weight (6MW), average daily gain from birth to weaning (ADG0–3), average daily gain from birth to 6-month (ADG0–6), average daily gain from weaning to 6-month (ADG3–6), and corresponding Kleiber ratio (KR0–3, KR0–6, KR3–6). Reproductive traits were litter size at birth (LSB), litter size at weaning (LSW), litter mean weight per lambing (LMWL), litter mean weight per lamb weaned (LMWLW), total litter weight at birth (TLWB) and total litter weight at weaning (TLWW). Moreover, multivariate analyses were performed to estimate covariance between traits. Direct heritability estimates (h2a) for growth traits ranged from 0.000 (ADG0–3 and KR0–3) to 0.156 (6MW). Maternal heritability (h2m) decreased from 0.110 at birth to 0.022 at 6-month weight. The ratio of maternal permanent environmental variance to phenotypic variance (pe2) persisted into the post-weaning growth period and it was 0.115, 0.080, 0.087 and 0.081, for BW, ADG0–6, KR0–3 and KR0–6, respectively. Estimates of h2a for reproductive traits were significant for LSB, LSW, LMWL and LMWLW being 0.175, 0.213, 0.088 and 0.034, respectively, while TLWB and TLWW were more affected by the permanent environmental effects of ewes. Service sire effects (S2) were significant for LMWL. Genetic correlations between growth traits ranged from −0.425 (BW-KR0–3) to 1.000 (6MW-ADG0–3, 6MW-KR0–3, ADG0–3–ADG3–ADG3–6-KR0–3 and KR0–3–KR0–6), and phenotypic correlations ranged from −0.341 (ADG0–3–KR3−6) to 0.990 (6MW–ADG0−6). Genetic correlations between reproductive traits were higher than phenotypic ones, and ranged from −0.986 (LSB-LMWLW) to 0.999 (LMWLW-TLWB).

Estimation of genetic parameters for reproductive traits in Mehraban sheep

Genetic parameters for basic and composite reproductive traits in Mehraban sheep were estimated. Data included 10 257 records on reproductive performances of 5813 lambs from 69 sires and 603 dams which were collected from 1994 to 2011 in the Mehraban breeding station in Hamedan province, western Iran. Studied traits were litter size at birth (LSB), litter size at weaning (LSW), litter mean weight per lamb born (LMWLB), litter mean weight per lamb weaned (LMWLW), total litter weight at birth (TLWB), and total litter weight at weaning (TLWW). Test of significance to include fixed effects in the statistical model was performed using the GLM procedure of SAS. Genetic parameters were estimated with univariate and bivariate repeatability animal models using WOMBAT program. Direct heritability estimates were 0.16, 0.14, 0.03, 0.16, 0.06, and 0.18 for LSB, LSW, LMWLB, LMWLW, TLWB, and TLWW, respectively, and corresponding repeatabilities were 0.02, 0.01, 0.73, 0.41, 0.27, and 0.03. The estimate for animal-dependent permanent environmental variance ranged from 0.01 ± 0.04 for LMWLW to 0.23 ± 0.04 for LSB. Genetic correlation estimates between traits ranged from −0.98 for LSB–LMWLW to 0.99 for LSB–TLWB. Phenotypic and environmental correlations were generally lower than genetic correlations. Phenotypic correlations ranged from −0.50 for LSB–LMWLB to 0.85 for LMWLW–TLWW. Environmental correlations ranged from −0.45 for LSB–LMWLB to 0.87 for LMWLW–TLWW. The results suggested that indirect selection based on TLWW could improve the reproductive performance in Mehraban ewes more effectively than if based on the other traits.

Ad libitum Pasture Feeding in Late Pregnancy Does Not Improve the Performance of Twin-bearing Ewes and Their Lambs.

The present study evaluated the effect of controlled ryegrass-white clover herbage availability from day 128 until day 142 of pregnancy in comparison to unrestricted availability, on the performance of twin-bearing ewes of varying body condition score (BCS; 2.0, 2.5, or 3.0) and their lambs. It was hypothesised that under conditions of controlled herbage availability, the performance of lambs born to ewes with a greater BCS would be greater than those born to ewes with a lower BCS. During the period that the nutritional regimens were imposed, the pre- and post-grazing herbage masses of the Control regimen (1,070±69 and 801±30 kg dry matter [DM]/ha) were lower than the ad libitum regimen (1,784±69 and 1,333±33 kg DM/ha; p<0.05). The average herbage masses during lactation were 1,410±31 kg DM/ha. Nutritional regimen had no effect on ewe live weight, BCS and back fat depth or on lamb live weight, indices of colostrum uptake, maximal heat production, total litter weight weaned or survival to weaning (p>0.05). The difference in ewe BCSs and back fats observed among body condition groups was maintained throughout pregnancy (p<0.05). At weaning, ewes from the BCS2.0 group had lower BCS and live weight (2.4±0.2, 74.3±2.6 kg) than both the BCS2.5 (2.6±0.2, 78.6±2.4 kg) and BCS3.0 ewes (2.7±0.2, 79.0±2.6 kg; p<0.05), which did not differ (p>0.05). Ewe BCS group had no effect on lamb live weight at birth or weaning or on maximal heat production (p>0.05). Serum gamma glutamyl transferase concentrations of lambs born to BCS3.0 ewes were higher within 36 hours of birth than lambs born to BCS2.0 ewes and BCS2.5 ewes (51.8±1.9 vs 46.5±1.9 and 45.6±1.9 IU/mL, respectively [p<0.05]). There was, however, no effect of ewe body condition on lamb plasma glucose concentration (p>0.05). Lamb survival was the only lamb parameter that showed an interaction between ewe nutritional regimen and ewe BCS whereby survival of lambs born to BCS2.5 and BCS3.0 ewes differed but only within the Control nutritional regimen ewes (p<0.05). These results indicate farmers can provide twin-bearing ewes with pre- and post-grazing ryegrass-white clover herbage covers of approximately 1,100 and 800 kg DM/ha in late pregnancy, provided that herbage covers are 1400 in lactation, without affecting lamb performance to weaning. The present results also indicate that under these grazing conditions, there is little difference in ewe performance within the BCS range of 2.0 to 3.0 and therefore they do not need to be managed separately.

Inbreeding effects on reproductive traits in Iranian Guilan sheep.

The objective of the present study was to evaluate the effects of inbreeding on reproductive traits in Guilan sheep. Traits included were litter size at birth (LSB), litter size at weaning (LSW), litter mean weight per lamb born (LMWLB), litter mean weight per lamb weaned (LMWLW), total litter weight at birth (TLWB), and total litter weight at weaning (TLWW). Data and pedigree information used in this study were collected during 1994 to 2011 by the Agriculture Organization of Guilan Province in the north of Iran. Data were comprised of 14,534 records of lambs from 136 sires and 2021 dams. All the animals were grouped into three classes according to the inbreeding coefficients (F) obtained by their pedigree: the first class included non-inbred animals (F = 0%), and the second and third classes included inbred animals (0 < F ≤ 5% and F > 5%, respectively). The regression coefficients of LSB, LSW, LMWLB, LMWLW, TLWB, and TLWW on lamb inbreeding for a change of 1% in inbreeding were estimated to be 0.035 ± 0.0038 (P < 0.001), -0.029 ± 0.0077 (P < 0.05), -0.333 ± 0.009 (P < 0.001), -2.21 ± 0.071 (P < 0.001), -0.254 ± 0.013 (P < 0.001), and -1.95 ± 0.093 (P < 0.001), respectively. Effect of inbreeding on reproductive traits in Guilan sheep was very pronounced in the flock. The utilization of a program for planned mating system, in the present flock, suggested keeping the level of inbreeding under control and avoiding appearance of its detrimental effects.

Genetic parameters and genetic gains for reproductive traits of Arabi sheep

The current study reports, for the first time, the genetic parameters and genetic, phenotypic and environmental correlations and trends of reproductive traits in Arabi sheep. Data were collected at Animal Science Research Station of Khuzestan Ramin Agricultural and Natural Resources University (ASRSKRANRU), south-west of Iran from 2001 to 2008. Litter size at birth (LSB), litter size at weaning (LSW), litter mean weight per lamb born (LMWLB), litter mean weight per lamb weaned (LMWLW), total litter weight at birth (TLWB) and total litter weight at weaning (TLWW) averaged 1.11 lambs, 1.01 lambs, 3.83 kg, 19.43 kg, 4.16 kg and 20.12 kg, respectively. Genetic parameters and correlations were estimated with univariate and bivariate models using restricted maximum likelihood, breeding values of animals were estimated with best linear unbiased prediction (BLUP) and genetic- and phenotypic trends by regression of ewes? average breeding values and phenotypic least square means on year of birth respectively. Random effects were fitted by additive direct genetic effects and permanent environment related to the ewe as well as service sire effects, in addition to fixed effects of ewe age at lambing and lambing year. Heritability estimates of 0.05, 0.02, 0.13, 0.12, 0.04, and 0.06, and repeatability estimates of 0.08, 0.06, 0.17, 0.16, 0.14 and 0.21 for the six traits, respectively. Genetic correlations between traits varied from ?0.82 to 0.94. Phenotypic correlations were lower, ranging from ?0.33 to 0.52. Estimated annual genetic progress was very low; ?0.003 lambs for LSW and 15 g for TLWW. Annual phenotypic trend was only significant for LSW being 0.007 lambs. The study concluded that indirect selection based on total litter weight at weaning could be efficient for the traits studied.

Effects of dietary enrichment with a marine oil-based n-3 LCPUFA supplement in sows with predicted birth weight phenotypes on birth litter quality and growth performance to weaning

The effects of a marine oil-based n-3 long-chain polyunsaturated fatty acid (mLCPUFA) supplement fed to the sow from weaning, through the rebreeding period, during gestation and until end of lactation on litter characteristics from birth until weaning were studied in sows with known litter birth weight phenotypes. It was hypothesized that low birth weight (LBW) litters would benefit more from mLCPUFA supplementation than high birth weight litters. A total of 163 sows (mean parity=4.9±0.9) were rebred after weaning. Sows were pair-matched by parity and litter average birth weight of the previous three litters. Within pairs, sows were allocated to be fed either standard corn/soyabean meal-based gestation and lactation diets (CON), or the same diets enriched with 0.5% of the mLCPUFA supplement at the expense of corn. Each litter between 9 and 16 total pigs born was classified as LBW or medium/high average birth weight (MHBW) litter and there was a significant correlation (P<0.001) between litter average birth weight of the current and previous litters within sows (r=0.49). Sow serum was harvested at day 113 of gestation for determination of immunoglobulin G (IgG) concentrations. The number of pigs born total and alive were lower (P=0.01) in mLCPUFA than CON sows, whereas the number of stillborn and mummified pigs were similar between treatments. Number of stillborns (trend) and mummies (P<0.01) were higher in LBW than MHBW litters. Tissue weights and brain : tissue weight ratios were similar between treatments, but LBW litters had decreased tissue weights and increased brain : tissue weight ratios compared with MHBW litters. Placental weight was lower (P=0.01) in LBW than MHBW litters, but was not different between treatments. Average and total litter weight at day 1 was similar between treatments. mLCPUFA increased weaning weight (P=0.08) and average daily gain (P<0.05) in MHBW litters, but not in LBW litters. Pre-weaning mortality was similar between treatments, but was higher (P<0.01) in LBW than MHBW litters. IgG concentration in sow serum was similar between treatments and litter birth weight categories. In conclusion, litter birth weight phenotype was repeatable within sows and LBW litters showed the benchmarks of intra-uterine growth retardation (lower placental weight and brain sparing effects). As maternal mLCPUFA supplementation decreased litter size overall, only improved litter growth rate until weaning in MHBW litters, and did not affect pre-weaning mortality, maternal mLCPUFA supplementation was not an effective strategy in our study for mitigating negative effects of a LBW litter phenotype.

Desempeño reproductivo de cerdas primerizas suplementadas con riboflavina durante la gestación

Para evaluar los efectos en el tamaño de lechigada y la expresión del factor de crecimiento endotelial vascular (VEGF; por sus siglas en inglés) y de la uteroferrlna, cerdas primerizas cruzadas (n = 24) se suplementaron con 0 o 60 mg de riboflavina diariamente durante toda la gestación. El tamaño de la lechigada y el peso individual de las crías se determinó al nacer y al destete. Se colectaron muestras de placenta al momento del parto para determinar la expresión relativa del VEGF y de la uteroferrina. Las cerdas suplementadas y no suplementadas parieron 11.2 ± 0.6 y 8.2 ± 0.6 cerditos totales, respectivamente (P &lt; 0.004). Hubo diferencias análogas en el número de cerditos nacidos vivos de 10.5 ± 0.6 contra 8.1 ± 0.6 (P &lt; 0.01) y en el número total de cerditos destetados (9.41 ± 0.6 y 7.5 ± 0.6, P &lt; 0.05). Se encontró diferencia entre los tratamientos para el peso total de la lechigada al nacer pero no al destete. La expresión relativa del VEGF fue mayor (P &lt; 0.07) en la placenta de cerdas suplementadas con riboflavina que en las controles, pero los tratamientos no difirieron en la expresión relativa de la uteroferrina. Los resultados presentes indican que la suplementación con 60 mg diarios de riboflavina a cerdas primerizas durante la gestación puede incrementar el tamaño de la lechigada, quizás mediado por una mejor vascularización de la placenta y por consiguiente mejorando la supervivencia del embrión/feto.

Effect of combination vitamin E and single long-acting progesterone dose on enhancing pregnancy outcomes in the first two parities of young rabbit does

Vitamin E (Vit. E) is needed for young rabbits to prevent reproductive abnormalities, abortion and poor survivability of kits. Also, exogenous progesterone (P4) is needed for rabbits to enhance early embryonic development because of inadequate corpus luteum (CL) development at this age. Hence, the aim of this study was to investigate the effect of injecting Vit. E and the combination Vit. E+P4 in young does on live body weight (LBW) gain, gestation length (GL), numbers of services/conception (NS), conception rate (CR), abortion rate (AR), litter size (LS), kit weight (KW), total litter weight (TLW), mortality rate (MR) and progesterone (P4) concentration. The group treated with Vit. E+P4 had a greater LBW gain and lesser AR at first and second pregnancy. Treatments did not have significant impact on GL and LS in the first two parities. Treatments resulted in a significantly lesser MR and greater TLW at the second parity. The Vit. E+P4 treatment resulted in a significantly lesser NS at the first parity, while Vit. E alone resulted in a significant reduction in NS at the second parity. Vit. E+P4 had a positive effect on CR at the first parity compared with controls. Vit. E alone increased CR at the second parity compared with that of the control group. The mean P4 concentration from mating to mid-pregnancy at first parity was significantly greater in the Vit. E+P4 than Vit. E and control groups. In conclusion, treatment with Vit. E+P4 at the first parity may be economically applied on rabbit farms because this treatment resulted in a greater maintenance of the first pregnancy and improved reproductive performance at the second parity as compared with results from the Vit. E treated and control groups.