Litter Weight At Birth Research Articles

Erythropoietin receptor gene polymorphism in Indian pig lines

A restriction fragment length polymorphism (RFLP) based genotyping test was developed to assess a C/T polymorphism in the regulatory region of erythropoietin receptor (EPOR) gene of pigs. Homozygous CC animals were absent in all the genetic groups studied, whereas the locus appeared fixed with T alleles in indigenous animals. The association of allelic variants with traits like litter size at birth (LSB), litter size at weaning (LSW), litter weight at birth (LWB) and litter weight at weaning (LWW) were explored in Indian Large White Yorkshire (LWY), Duroc, Indigenous Ankamali and F1 crosses between LWY boars and Ankamali sows (CB). All the populations under study had very high frequency of T alleles, with desi group being fixed with T allele. Genotypes of EPOR gene were not associated with any of the litter traits. The allele frequencies remained under HWE except in desi group.

Environmental effects on productive and reproductive performance of Pelibuey ewes in Southeastern México

ABSTRACTThe objective of this study was to determine the effect of some environmental factors on reproductive and productive performance traits and to estimate their repeatability in Pelibuey ewes in Yucatan, Mexico. Information of 956 Pelibuey ewes lambing from 2007 to 2013 in three farms were used (n = 2215 lambing). The assessed traits were age at first lambing (AFL), lambing interval (LI), litter size at birth (LSB), litter size at weaning (LSW), litter weight at birth (LWB) and litter weight at weaning adjusted to 60 days (LWWA). Mixed models were used to determine the effects of farm, lambing season or birth, year of lambing or birth and parity number on above traits. Repeatability were calculated using the between and within ewe components of variance. Overall means and standard deviations for AFL, LI, LSB, LWB, LSW and LWWA were 526.7 ± 107.1d, 259.4 ± 70.3d, 1.5 ± 0.6, 4.3 ± 1.6 kg, 1.4 ± 0.7 and 19.1 ± 10.1 kg, respectively. Repeatability for LI, LSB, LSW, LWB and LWWA were 0.06 ± 0.20, 0.12 ± 0.04, 0.00 ± 0.04, 0.13 ± 0.04 and 0.01 ± 0.04, respectively. AFL was not affected by any of the environmental factors. However, the other traits were influenced (p < .05) by farm, lambing year, lambing season, parity and LSB (for LI and LSW). In conclusion, productive and reproductive performance traits of Pelibuey ewes were influenced by environmental factors, and repeatability were lows. To improve the performance of Pelibuey ewes adjustments to management schemes should be made as well as to base the selection on more than one productive and reproductive indicator.

Analysis of Reproductive Traits of Broiler Rabbits Reared in Sub-temperate Climate of Kodai Hills, Tamil Nadu, India.

Aim:The present study was carried out at Institute Rabbit Farm of Southern Regional Research Centre, Mannavanur, Kodaikanal, Tamil Nadu, India having sub-temperate climate with winter temperature during night hours going below 0°C with an objective of finding the influence of different factors such as breed, year, season and parity on different reproductive traits of broiler rabbits in order to come out with the best strategies for improving the productivity.Materials and Methods:A total of 1793 records (946 White Giant and 847 Soviet Chinchilla) for weight at mating (WM), weight at kindling (WK), gestation length (GL), litter size at birth (LSB) and litter size at weaning (LSW), litter weight at birth (LWB), and litter weight at weaning (LWW) were collected in the period between 2000 and 2009 and the data was analyzed using general linear model option of SAS 9.2.Results:The overall mean GL, WM, WK, LSB, LSW, LWB, and LWW were 31.68±0.04 days, 3.65±0.01 kg, 3.84±0.01 kg, 6.91±0.08, 5.49±0.09, 387.62±4.07 g, and 4.66±0.07 kg, respectively. The breed has significantly influenced GL, WK, LSW, LWB, and LWW. The LSB, LSW, LWB, and LWW were 7.05±0.11, 5.76±0.13, 399.55±5.88 g, and 4.87±0.10 kg, respectively in White Giant and corresponding values for Soviet Chinchilla were 6.78±0.11, 5.22±0.12, 375.91±5.64 g, and 4.46±0.09 kg, respectively. The year of kindling had significantly affected all the reproductive traits under study and is varying over different years. The parity significantly influenced the WM, WK, and LWW. The LWW increased from first (4.16±0.21 kg) to second parity (4.86±0.19 kg) and remained in the same range from third parity onward. WM was significantly higher in spring season (3.72±0.02) than the animals in rainy (3.59±0.02) and winter season (3.65±0.02). Better reproductive performance in terms of higher LSB, LSW, LWB, and LWW as observed in the present study might be due to conducive environmental conditions prevailing in the region.Conclusion:The significant effects of the non-genetic factors like year of kindling on all reproductive traits, season, and parity on some of the traits in rabbit breeds are indications that any future production enhancement strategy must take into consideration the environment by providing additional care, feed supplementation and better shelter management to the rabbits, so that the full genetic potential can be realized.

Analysis of performances in white giant rabbits reared in sub-temperate climate of Kodai hills, Tamil Nadu

The present study was carried out at Institute Rabbit Farm of ICAR-Southern Regional Research Centre, Central Sheep and Wool Research Institute, Mannavanur, Kodaikanal, Tamil Nadu, India which is located at 2030 metre above mean sea level. The climatic conditions prevailing in the region is sub-temperate with winter temperature during night hours going below zero °C. The objective of investigation was to find out the influence of different factors such as year, season and parity on different litter traits and pre-weaning growth of White Giant rabbits in order to come out with the best strategies for improving the productivity of these rabbits. A total of 946 records for litter size at birth (LSB) and weaning (LSW), litter weight at birth (LWB) and weaning (LWW) were collected in the period between 2000 to 2009 and the data was analyzed using General Linear Model option of SAS 9.2. The overall LSB, LSW, LWB and LWW were 7.067±0.11, 5.788±0.13, 400.00±5.99g and 4.877±0.10 kg, respectively. All the litter traits varied significantly year-wise, however, they were not varying significantly parity-wise except LWW which increased progressively from first parity (4.364 ± 0.32 kg) to fifth parity (5.612 ± 0.27 kg). The season of kindling did not have significant role in affecting different litter traits and the values were comparable. The year, season and sex had significantly (P>0.01) influenced both weaning weight at six weeks and pre-weaning ADG. The growth was better in male animals as evident from higher body weight at six week age and average daily gain (853.090 ± 3.49 g and 19.123 ± 0.08 g/day vs. 820.493 ± 3.53 g and 18.347 ± 0.08 g/day). Rabbits born during winter months gained more weight (876.055 ± 4.86 g and 19.670 ± 0.12 g/day) while performance of rabbits born during spring and rainy season were comparable. The significant effects of the non-genetic factors like year of kindling on all litter traits, individual weight at weaning and pre-weaning ADG, season and parity on some of the traits are indications that any future breed development strategy must take into consideration the environment by providing additional care, feed supplementation and better shelter management to the rabbits so that the full genetic potential can be realized.

Heat stress, divergent nutrition level, and late pregnancy in hair sheep: effects upon cotyledon development and litter weight at birth.

The effect of two divergent nutritional levels during late pregnancy upon some physiological variables and the number (NC) and diameter (DC) of placental cotyledons along with litter weight at birth (LWB) on heat-stressed (42-45°C) hair ewes was evaluated. Multiparous Katahdin x Pelibuey ewes (n = 24) at the onset of the 3/3 of pregnancy were randomly assigned to two treatments (n = 12): (1) non-nutritionally restricted (NNR) ewes, with free access to wheat straw plus 500g/day of concentrate, and (2) nutritionally restricted (NR) ewes, receiving only wheat straw ad libitum. On days 100, 115, 130, and 145 of gestation, the body weight (BW), body condition score (BCS), rectal temperature (RT), respiration rate (RR) were registered in the afternoon (15:00) while the temperature-humidity index (THI) was calculated. At lambing, NC, DC, and LWB were also registered. Analyses considered a completely random design (CRD)-ANOVA with repeated measures across time, considering to litter size (LS) as covariable to reduce any possible influence of LS upon the response variables along experimental diets. BW and BCS were higher in NNR ewes at days 115, 130, and 145. Despite RT similarities (P < 0.05) between treatments, RR was greater (P < 0.01) in the NNR ewes, particularly towards the end of the experimental period. The observed THI averages confirmed severe heat stress conditions on ewes all day round across the experimental period, yet, NC, DC, and LWB favored (P < 0.05) to the NNR ewes. Despite that NNR ewes faced a significant heat stress based on the observed THI values, they consumed a diet with an increased energy-protein density, suggesting that the increased RR in the NNR group was exerted as a compensatory thermoregulation mechanism. Nutritional supplementation in hair ewes besides to an increase the energy body reserves (BW and BCS) also improved both the number and size of cotyledons, while generated an increased litter weight at birth.

Grupo genético e ordem de parto no desempenho produtivo e reprodutivo de matrizes suínas

&lt;p&gt;O objetivo com este trabalho foi avaliar o efeito de grupo genético (GGen) e de ordem de parto (OrdP) de 400 matrizes suínas sobre características produtivas e reprodutivas. Utilizou-se três GGen (GGen1, GGen2 e GGen3) e duas OrdP (OrdP1 e OrdP2). As variáveis dependentes avaliadas foram peso médio da leitegada ao nascimento (PMNasc), peso médio da leitegada ao desmame (PMDesm), tamanho da leitegada ao nascimento (TNasc), tamanho da leitegada ao desmame (TDesm), duração da lactação (DL), número de partos/fêmea/ano (P/F/A), número de leitões desmamados/fêmea/ano (D/F/A), ganho de peso diário do leitão (GPD), ganho de peso diário da leitegada (GPDLeit), intervalo desmame-cio (IDC), média de dias não produtivos (MDNP) e número de serviços por concepção (NSPC). A interação entre GGene OrdPfoi significativa para PMDesm, DL, P/F/A, GPD, IDC e MDNP. Para as demais variáveis (PMNasc, TNasc, TDesm e D/F/A) não ocorreu interação nem efeito de GGen e OrdP. Houve efeito do GGen independente da OrdP nas variáveis GPDLeit e do NSPC. O GGen 3 foi considerado superior, uma vez que este apresentou melhor desempenho em relação aos demais na maioria das características avaliadas. Não foi possível determinar a melhor OrdP, pois esta variou em função dos GGen e das variáveis dependentes.&lt;/p&gt;

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.

Genetic parameters for growth and reproductive traits of Morada Nova sheep kept by smallholder in semi-arid Brazil

The objective of the present study was to estimate genetic parameters for growth and reproductive traits of Morada Nova sheep reared by smallholder farmers in the semi-arid northeastern region of Brazil. Data from 11 participating flocks, between 2007 and 2011, were used for the estimation of (co)variance components and genetic parameters for birth weight (BW), weight at weaning adjusted for 112 days of age (WW), average daily weight gain from birth to weaning (ADG), days to lambing (DL), lambing interval (LI), total litter weight at birth (LWB), total litter weight at weaning (LWW) and the ratio between total litter weight at birth and weaning and metabolic weight of the dam (LWB/MW and LWW/MW, respectively). The direct heritabilities obtained by one-trait analysis were 0.19, 0.14, 0.11, 0.13, 0.0, 0.44, 0.19, 0.41, 0.15, respectively for BW, WW, ADG, DL, LI, LWB, LWW, LWB/MW and LWW/MW. The direct heritabilities for BW and WW obtained by two-trait analysis were similar to those estimated by one-trait analysis. However, the direct heritabilities for LWB, LWW and LWW/MW obtained by two-trait analysis were higher than those estimated by one-trait analysis. The genetic correlation between BW and WW were 0.75 and between LWB, LWW and LWW/MW were 0.8, 0.9 and 1.0, respectively. In conclusion, except for LI, there is genetic variability that can be explored by direct and indirect selection to obtain genetic gains in the flocks participating in the Nucleus of Participatory Breeding of Morada Nova Sheep.

Reproductive performance of different breeds of broiler rabbits under sub-temperate climatic conditions

This study was conducted to assess the effect of breed, season, age and weight of doe at mating on reproductive performance of 4 broiler rabbit breeds, Grey Giant, White Giant, Soviet Chinchilla, and New Zealand White, reared under standard management practices in sub-temperate climatic conditions of India. They were first mated at 6 to 7 mo of age, whereupon an extensive breeding system (re-mating after weaning) was followed. Weaning was done 42 d after kindling. The data from the records on reproduction consisting of 503 matings and 377 kindlings were analysed. The parameters considered were fertility rate, litter size at birth (LSB), litter weight at birth (LWB), litter size at weaning (LSW), litter weight at weaning (LWW), doe weight at mating (DWM), gestation length and sex ratio. Among 4 breeds, the LSB, LWB and LSW were higher in Grey Giant followed by White Giant, Soviet Chinchilla and New Zealand White. The LSB and LSW in Grey Giant breed differed significantly (P<0.05) from Soviet Chinchilla and New Zealand White. Season had significant (P<0.05) effect on LSW with higher values during spring (5.68±0.24), followed by summer (5.29±0.30), winter (5.13±0.25) and autumn (4.17±0.49). The body weight of doe at service significantly influenced fertility. The fertility increased as body weight increased. The age of the doe at mating had a significant effect on LSW, with higher values for does more than 2 yr and less than 1 yr old compared to 1- to 2-yr old does. The parity did not affect any of the parameters studied. It is concluded that the factors studied affect the reproductive performance of rabbit does. Grey Giant breed showed the highest litter size at birth and weaning, and the highest litter size and weight at weaning was in spring.

Estimation of genetic parameters and genetic gains for reproductive traits and body weight of D’man ewes

The current study consisted of genetic analysis for reproductive performance and body weight using from 2003 to 2863 records of 1018 D’man ewes born from 136 sires and 468 dams. Data were collected from 1988 till 2009 in the Errachidia Experimental Station (ESE) of the Institut National de la Recherche Agronomique. Conception rate (CR), litter size at birth (LSB), litter size at weaning (LSW), litter weight at birth (LWB), litter weight at weaning (LWW), gestation length (GL) and ewe's body weight (EBW) averaged 94.4%, 2.38 lambs, 2.03 lambs, 6.23kg, 39.6kg, 149.9 days and 44.8kg, respectively. The analysis of variance showed that LWB and EBW were influenced by age of ewe, parity and period of lambing. Also, period of lambing had significant effects on all studied traits. However, age of the ewe did not affect LSB and LWW. Genetic parameters and genetic trends for reproductive traits and EBW, estimated through REML and BLUP procedures using a repeatability animal model including additive genetic and permanent environment effects, in addition to fixed effects, resulted in heritability estimates of 0.09, 0.11, 0.10, 0.10, 0, 0.22 and 0.44 and repeatability estimates of 0.19, 0.13, 0.16, 0.10, 0, 0.26 and 0.62 for LSB, LSW, LWB, LWW, CR, GL and EBW, respectively. Genetic correlations among traits ranged from −0.21 and 0.93 and phenotypic correlations varied from −0.07 to 0.82. Estimated annual genetic progress was very small; 0.0009 lambs for LSB and −0.0078kg for EBW. The study concluded that the actual genetic parameter estimates could be used in a breeding program to improve the productivity of D’man ewes and to make significant genetic progress.

English

The aims of the study were to investigate the fixed effects which are considered to influence ewe productivity and to estimate the genetic parameters for ewe productivity traits of Lohi sheep. Genetic parameters were estimated by restricted maximum likelihood (REML) procedure using the GENSTAT program. The effects of year and age of ewe were significant for fertility, litter size at birth (LSB), litter size at weaning (LSW), litter weight at birth (LWB) and litter weight at weaning (LWW). The least squares means of fertility, LSB, LSW, LWB and LWW were 0.904, 1.422, 1.358, 6.689 kg and 41.577 kg, respectively. The means of total number of lambs born (TLB), total number of lambs weaned (TLW), total birth weight of lambs (TWB) and total weight of lambs weaned (TWW) per ewe over four lambing opportunities were 5.48, 5.25, 25.61 kg and 162.47 kg, respectively. Estimates of heritability for fertility, LSB, LSW, LWB and LWW were 0.0250, 0.0533, 0.0430, 0.0462 and 0.0255, respectively; and estimates of repeatability for these traits were 0.1242, 0.0787, 0.0772, 0.0882 and 0.0715, respectively. The low estimates of heritability and repeatability obtained in the current study for ewe productivity traits indicate that selection based on the ewe's own performance may result in slow genetic improvement. Key words: Genetic parameter, litter size, ewe productivity.

Estimation of Heritability and Repeatability for Pre-Weaning and Post Weaning Litter Weights of Unselected Domestic Rabbits in South Eastern Nigeria

Data from one hundred and seventy eight (178) kittens generated from 21 does mated to 7 stud bucks resulting in 34 kindling were used to estimate the heritability due to sire and repeatability for birth, weaning and post weaning litter weight traits of unselected non-descript rabbits reared in FUTO teaching and research farm. Traits such as litter weight at birth (LWB), at weaning i.e. 21d (LWW), 42d (LW42), 56d (LW56) were studied. A repeatability single trait animal model was used to analyze the data Estimates of Sire heritability for LWB, LWW, LW42 and LW56 were 0.34±0.41, 0.79±0.632, 0.91±1.20 and 0.62±0.542 while repeatability estimate were 0.034±0.243, -0.130±0.197, 0.003±0.236 and 0.008±0.238 respectively. These estimates indicate a moderate to high heritability while the repeatability indicates generally low estimates. This implies that selection of this non-descript population of rabbits for LWW, LW42 and LW56 could be efficient in improving these traits in the population, while the repeatability of these traits being very low, suggests that the likelihood to repeat these records is low.

Genetic parameter estimates for growth traits and prolificacy in Raeini Cashmere goats

The main objectives of this study were to estimate genetic and phenotypic parameters for growth traits and prolificacy in the Raeini Cashmere goat. Traits included, birth weight (BWT), weaning weight (WWT), 6-month weight (6WT), 9-month weight (9WT), 12-month weight (12WT), average daily gain from birth to weaning (ADG1), average daily gain from weaning to 6WT (ADG2), average daily gain from 6WT to 12WT (ADG3), survival rate (SR), litter size at birth (LSB) and litter size at weaning (LSW) and total litter weight at birth (LWB). Data were collected over a period of 28 years (1982-2009) at the experimental breeding station of Raeini goat, southeast of Iran. Genetic parameters were estimated with univariate models using restricted maximum likelihood (REML) procedures. In addition to an animal model, sire and threshold models, using a logit link function, were used for analyses of SR. Age of dam, birth of type, sex and of kidding had significant influence (p < 0.05 or 0.01) all the traits. Direct heritability estimates were low for prolificacy traits (0.04 ± 0.01 for LSB, 0.09 ± 0.02 for LSW, 0.16 ± 0.02 for LWB and 0.05 ± 0.02 for SR) and average daily gain (0.12 ± 0.03 for ADG1, 0.08 ± 0.02 for ADG2, and 0.07 ± 0.03 for ADG3) to moderate for production traits (0.22 ± 0.02 for BWT, 0.25 ± 0.02 for WWT, 0.29 ± 0.04 for 6WT, 0.30 ± 0.02 for 9WT, 0.32 ± 0.05 for 12WT). The estimates for the maternal additive genetic variance ratios were lower than direct heritability for BWT (0.17 ± 0.03) and WWT (0.07 ± 0.02).

Genetic and phenotypic parameter estimates for reproduction traits in indigenous Arsi-Bale goats

The study was conducted to evaluate reproductive performances and estimate genetic parameters for reproduction traits in Arsi-Bale goats. A total of 792 kidding records collected from 2001 to 2007 were used. Parity of dam, year, season and type of kidding were investigated as fixed effects by PROC GLM of SAS. Derivative-Free Restricted Maximum Likelihood (DFREML) method was used to estimate genetic parameters by fitting four animal models. Parity of dam and year of kidding influenced (P < 0.05) all the traits. The overall means for age at first kidding (AFK), kidding interval (KI), litter size at birth (LSB), litter size at weaning (LSW), litter weight at birth (LWB), litter weight at weaning (LWW), abortion and dystocia were 574.9 ± 8.3 days, 280.0 ± 13.7 days, 1.6 ± 0.03, 1.37 ± 0.03, 3.7 ± 0.08 kg, 9.11 ± 0.38 kg, 3.8% and 0.13%, respectively. The estimates of direct additive heritability for the traits, except for abortion and dystocia, under the best model (direct animal for AFK and repeatability model for other traits) were 0.245 ± 0.19, 0.060 ± 0.08, 0.074 ± 0.05, 0.006 ± 0.05, 0.125 ± 0.05, 0.053 ± 0.07, respectively, while the corresponding permanent environmental effects were 0.00 ± 0.00, 0.07 ± 0.07, 0.08 ± 0.05, 0.172 ± 0.06, 0.03 ± 0.04 and 0.07 ± 0.05, respectively. Repeatability estimates for KI, LSB, LSW, LWB and LWW were 0.13, 0.15, 0.18, 0.16 and 0.12, respectively. Genetic correlations between reproductive traits vary from medium to high. Arsi-Bale goats have good reproductive performance with low incidence of reproductive disorder. Except for AFK, other traits have low estimates of heritabilities with high genetic correlation among the traits. Repeated measures of the traits are needed before deciding to keep or cull the animal.

Genetic (co)variance components for ratio of lamb weight to ewe metabolic weight as an indicator of ewe efficiency

Data from a multibreed commercial flock located at Mid-West of Brazil, supported by Programa de Melhoramento Genético de Caprinos e Ovinos de Corte (GENECOC), were used to estimate genetic parameters of traits related to ewe productivity by Average Information Restricted Maximum Likelihood method applied to an animal model. The analyzed traits were litter weight at birth (LWB) and at weaning (LWW), ewe weight at weaning (EW) and ewe production efficiency, estimated by WEE=LWW/EW0.75. The heritabilities were 0.26±0.05, 0.32±0.06, 0.37±0.03 and 0.10±0.02 for LWB, LWW, EW and WEE, respectively. Significant effects for direct heterosis were observed for LWW and EW. Recombination losses were important for EW and WEE. Genetic correlations of LWB with LWW, EW and WEE were 0.68, 0.37 and 0.15, respectively; of LWW with EW and WEE were 0.30 and 0.34, respectively; and between EW and WEE was −0.25. Even though it is a low heritability trait, WEE can be indicated as a selection criteria for improving the ewe productivity without increasing the mature weight of animals due to its genetic correlations with LWW and other traits.

Polymorphism in exon 3 of follicle stimulating hormone beta ( FSHB) subunit gene and its association with litter traits and superovulation in the goat

The polymorphism in follicle stimulating hormone beta ( FSHB) subunit gene was detected by PCR-SSCP and PCR-RFLP methods in 780 does from four goat breeds including Boer, Matou, Black and Boer–Matou crossbred (BM). The associations of FSHB genotypes with litter size (LS), litter weight at birth (LWB) and gestation length (GL) as well as superovulation performances were analyzed in relatively lower-prolific Boer and higher-prolific Matou breeds. A 1514 bp linear DNA sequence of goat FSHB gene covering the complete 3 exons was cloned by four pairs of primer. A new mutation (A2645G, GenBank Accession no: S64745) locating in exon 3 causing an amino acid change from glutamine (Gln) to arginine (Arg) at residue 115 was identified, which resulted in three genotypes named AA, AB and BB. The three genotypes were detected in the four studied goat breeds. The higher-prolific Matou breed had the highest frequency of genotype AA. Association analysis showed that Boer and Matou does with AA genotype have the largest LS both in average and in parities from first to fourth ( P < 0.05). Furthermore, Boer does with AA genotype had the heaviest LWB compared to other two genotypes ( P < 0.05). Matou does with AA genotype have more numbers of ova harvested, large follicles and corpus lutea on ovaries after superovulation than those with BB genotype ( P < 0.05). Therefore, these results suggest that the FSHB gene is a candidate gene that affects reproduction traits in goats.

Reproductive efficiency of female German Angora Rabbits under Indian sub-temperate climatic conditions.

The influence of season, parity, age and weight of doe at service on the reproductive efficiency of female German Angora rabbits has been studied. Nulliparous German Angora rabbits of 4 - 5 months of age were imported from Germany in August, 1997 and reared under standard management practices. They subjected to an extensive breeding system (re-mating after weaning). The kits were weaned 42 days after kindling. The data from the reproduction records of 149 does, consisting of 398 matings and 238 kindlings during a period of five years, (1998 to 2002) were analyzed. The parameters considered were fertility rate, litter size at birth (LSB), litter weight at birth (LWB), litter size at weaning (LSW), gestation length and sex ratio. The overall fertility percentage, LSB, LWB (g), LSW (g), gestation length (d) and sex ratio percentage were 61.18, 4.89, 253.88, 4.44, 31.95 and 53.94, respectively. The season of the year had a significant (P#0.05) effect on LSB, LWB, LSW and gestation length, with higher values of LSB, LWB and LSW in spring. The fertility rate was significantly higher (P#0.05) for the females of 1 to 2 years of age. Spring appears to be the most favorable season for efficient reproduction of German Angora rabbits under the sub-temperate climatic conditions found in India.

Genetic and phenotypic parameter estimates for reproduction traits in the Boer dam

Variance components and further phenotypic and genetic parameters for reproduction traits including litter size at birth (LSB) and at weaning (LSW), gestation period (GP) and litter weight at birth (LWB) were estimated by use of the MTGSAM procedure fitting two-trait animal model ( y = X b + Z a a + Z P P + e ) in Boer dams. The calculations were based on 1205 parities of 435 Boer dams at Boer Goat Breeding Station in Yidu, China, during 2002–2007. Influencing factors such as parity and age of dam, kidding year and season, litter size at birth, sex of kids and some significant interactions were investigated as the fixed effects by PROC GLM (SAS8.1). The results showed that kidding year, parity and age of dam significantly influenced all the reproduction traits. Kidding season only affected the traits of GP and LWB. Litter size at birth had significant effect on LWB. The mean values of LSB, LSW, LWB and GP were 1.76 ± 0.67, 1.62 ± 0.62, 6.54 ± 2.51 kg and 151.7 ± 4.43 days. The estimates of direct additive heritability for above traits were 0.12 ± 0.01, 0.10 ± 0.01, 0.14 ± 0.02 and 0.09 ± 0.01, respectively. The estimates of all the correlations among LSB, LSW and LWB were higher than 0.52, and the genetic correlations were the highest among all the correlations. The estimates of genetic correlations between GP and other traits were medium (0.33–0.48) and lower than the permanent environmental correlations (0.60–0.72). In conclusion, compared with other goat breeds, the Boer goat has good characteristic in prolificacy. The gestation period is not significantly different in dams with increase of litter size, which is similar to the multiple birth species such as pig. However, the heritability estimates for all these reproduction traits obtained in the Boer dams are lower than 0.14; both LSB and LWB are traits with the highest heritability among 4 reproduction traits estimated. High genetic and permanent environmental correlations indicate that these traits were mainly attributable to different genetic effects or influenced by the permanent environmental effect for the different parity.

Genetic parameters for growth, reproductive and maternal traits in a multibreed meat sheep population

The genetic parameters for growth, reproductive and maternal traits in a multibreed meat sheep population were estimated by applying the Average Information Restricted Maximum Likelihood method to an animal model. Data from a flock supported by the Programa de Melhoramento Genético de Caprinos e Ovinos de Corte (GENECOC) were used. The traits studied included birth weight (BW), weaning weight (WW), slaughter weight (SW), yearling weight (YW), weight gain from birth to weaning (GBW), weight gain from weaning to slaughter (GWS), weight gain from weaning to yearling (GWY), age at first lambing (AFL), lambing interval (LI), gestation length (GL), lambing date (LD - number of days between the start of breeding season and lambing), litter weight at birth (LWB) and litter weight at weaning (LWW). The direct heritabilities were 0.35, 0.81, 0.65, 0.49, 0.20, 0.15 and 0.39 for BW, WW, SW, YW, GBW, GWS and GWY, respectively, and 0.04, 0.06, 0.10, 0.05, 0.15 and 0.11 for AFL, LI, GL, LD, LWB and LWW, respectively. Positive genetic correlations were observed among body weights. In contrast, there was a negative genetic correlation between GBW and GWS (-0.49) and GBW and GWY (-0.56). Positive genetic correlations were observed between AFL and LI, LI and GL, and LWB and LWW. These results indicate a strong maternal influence in this herd and the presence of sufficient genetic variation to allow mass selection for growth traits. Additive effects were of little importance for reproductive traits, and other strategies are necessary to improve the performance of these animals.

Crossbreeding effects for litter and lactation traits in a Saudi project to develop new lines of rabbits suitable for hot climates

A five-years crossing scheme involving the Spanish V line (V) and Saudi Gabali (S) rabbits was practiced to produce 14 genetic groups: V, S, 1/2V1/2S, 1/2S1/2V, 3/4V1/4S, 3/4S1/4V, (1/2V1/2S) 2, (1/2S1/2V) 2, (3/4V1/4S) 2, (3/4S1/4V) 2, ((3/4V1/4S) 2) 2, ((3/4S1/4V) 2) 2, Saudi 2 (a new synthetic line) and Saudi 3 (another new synthetic line). A total of 3496 litters from 1022 dams were used to evaluate litter size at birth (LSB) and weaning (LSW), litter weight at birth (LWB), litter weight at 21 d (LW21) and litter weight at weaning (LWW), pre-weaning litter mortality (PLM), milk yield at lactation intervals of 0–7 d (MY07), 0–21 d (MY021), 0–28 d (TMY) and milk conversion ratio as g of litter gain per g of milk suckled during 21 d of lactation (MCR021). A generalized least squares procedure was used to estimate additive and heterotic effects (direct, maternal, and grand-maternal). The comparison among V, S, Saudi 2 and Saudi 3 showed a complementarity between V and S. Line V was superior for LSB, LSW, LWB, PLM, MY07, MY021 and TMY, while line S was superior for the other traits (LW21, LWW and MCR021). Saudi 2 and Saudi 3 had the means equal to or higher than the founder lines (V or S) for all traits. Saudi 2 showed better values in litter size and pre-weaning litter mortality compared to Saudi 3 with no significant differences for the other traits. Concerning crossbreeding parameters, direct additive effects were significant for all traits, ranging between 12.3% and 31.8% relative to the average of the means of V and S. All estimates for direct heterosis except LWB and MCR021 were significant and ranged from 5.3% to 27.5%. No estimates for maternal additive effects and grand-maternal additive and heterotic effects were significant. Only estimates for maternal heterotic effects of LSB and LSW were significant (8.6% and 10.6%, respectively).