Dam Line Research Articles

Reproductive performance of one-year-old Pacific abalone (Haliotis discus hannai) and its crossbreeding effect on offspring growth and survival

The Pacific abalone (Haliotis discus hannai) is one of the most popular farming mollusks in China, where three- to four-year-old adults are used as broodstock for commercial seeding. However, no reports exist regarding the reproduction performance of one-year-old Pacific abalone and its potential use in commercial breeding. In this study, one line of one-year-old abalone (AO) and two lines of three-year-old abalone (BD and HD), which were selected for rapid growth for three or six generations, were adopted to establish three purebred groups (AO, BD and HD) and two crossbred groups (BDAO and HDAO). The performance of these five groups on embryonic development, growth and survival rate was evaluated. According to the results, the average yolk diameter of oocytes produced by one-year-old abalone was significantly smaller than that produced by three-year-old individuals. The fertilization rate of the AO group was significantly higher than those of the other four groups, while the metamorphosis rate was the opposite. During the first 40d, the average shell growth rate of the AO group was slower than those of the other four groups, while the average shell length of this group was greatest after 120d. The AO group also showed a significantly higher survival rate than those of other groups during the period from 38d to 160d post fertilization. No significant differences were found in the embryonic development parameters or shell growth rates between the purebred and crossbred groups that shared the same dam line. However, the survival rates of the crossbred groups were significantly higher than those of the purebred groups. These results suggest that one-year-old Pacific abalone could be used as broodstock for reproduction and that an accelerated breeding cycle may enhance commercial genetic improvement programs.

Parental sex effect of parthenogenesis on hatchability and sperm-egg penetration in mated Chinese Painted quail (Coturnix chinensis)

Selecting quail for an increased incidence of parthenogenesis also impacts egg weight and albumen pH as well as reduces hatchability and fertility due to decreased sperm-egg penetration (SEP). However, it is unknown which parental sex is responsible for these changes in quail selected for parthenogenesis. Therefore, the objective of this study was to determine which sex influences egg weight, albumen pH, hatchability, and SEP in birds selected for parthenogenesis. In this study, 2 lines of birds were used: 1 line that was selected for parthenogenesis and 1 line not selected for parthenogenesis (control). Treatments were as follows: control females w/control males, control females w/parthenogenetic line males, parthenogenetic line females w/control males, and parthenogenetic line females w/parthenogenetic line males. Fresh eggs were collected daily, labeled and analyzed for albumen pH and SEP or incubated at 37.5 °C for 20 d of incubation. Eggs were candled at 10 days of incubation (DOI) and eggs exhibiting little or no embryonic development were removed and broken open to determine hatching failure. This was repeated at 20 DOI for eggs that did not hatch. A dam main effect for egg set weight existed with parthenogenetic line dams exhibiting heavier eggs than control dams. The parthenogenetic line dams and sires exhibited lower albumen pH and hatch but a higher incidence of parthenogenesis than control line dams or sires. However, only a sire main effect existed for fertility and SEP. Sires from the parthenogenetic line yielded the highest infertility due to lower SEP. In conclusion, both the parthenogenetic line dams and sires contribute to reduced reproductive performance. However, it appears that the sire from the parthenogenetic line is responsible for lower fertility due to a reduction in SEP. Because the sire has a negative impact on overall fertility, it is possible that males selected for parthenogenesis have poorer semen quality resulting in fewer sperm traversing the oviduct or penetrating the perivitelline layer.

Effect of long term selection for juvenile body weight and egg production on semen quality in broiler breeder dam line

Effect of long term selection for juvenile body weight and egg production on semen quality in broiler breeder dam line

Evaluating Breed Complementarity and Sexed Semen with Maternal Use of Afrikaner Germplasm

Livestock production impacts food security of developing countries, especially where efficiency of production is compromised by environmental stressors. In South Africa, breeding with indigenous Afrikaner cattle that are genetically well adapted to subtropical environments is considered an essential strategy for sustainable beef production. Today, there is a potential for farmers to participate in commercial systems that join adapted Afrikaner germplasm, used in a specialized maternal role, with exotic terminal sires to optimize production. The objective of this study was to assess productivity of five simulated production systems: 1) straightbred Afrikaner mated naturally, 2) a straight-bred Afrikaner cow herd with two sections; one section to produce replacement females and the other to cross with Charolais terminal sires, both using natural mating, 3) similar to 2, but applying sexed semen to produce replacement females, 4) similar to 2, but using a multi-breed composite dam line with a breed combination of 50% Afrikaner, 25% Hereford and 25% Simmental, and 5) similar to 4, but again applying sexed semen to produce replacement females. Parameter estimates needed to compare these systems were extracted from the scientific literature. Relative to straightbred Afrikaner dams, the simulated composite dams were more fit producing 7.8% more calves and their progeny performance was improved by reducing feed intake (-24.4%) and increasing meat production (+11.7%). The potential benefit of allocating more cows to the terminal sire was insufficient to offset the reduction in pregnancy rate that results with the use of sexed semen. Thus, system 4 had the greatest productivity (+23.1%) while requiring 22.8% less feed for finishing the progeny to be harvested relative to the purebred Afrikaner system. The combination of increased productivity and reduced feed requirement made use of a Charolais terminal sire in conjunction with multi-breed composite females bred by natural service the most efficient system among those studied.

Estimation of genetic parameters of various economic traits in a synthetic broiler dam line

A study to estimate heritability, genetic and phenotypic correlations for growth and egg production traits was carried out with the data pertaining to1624 broiler dam line maintained at Poultry Breeding Farm of Department of Animal Genetics and Breeding, LUVAS, Hisar. Traits recorded during the study were body weights at 6, 20 and 40 weeks, age at first egg, egg weight, egg number, egg mass, clutch, pause size up to 40 weeks of age, percent fertility of selected pullets, percent hatchability on total egg set basis and percent hatchability on fertile egg set basis. As per results, the pooled least squares means of BW6, BW20 BW40 AFE, EN40 EW40, EM40 CS, PS, PF, TES and FES 832.81±4.80 g, 2314.24±23.33 g, 2912.49±30.31 g, 147.89±0.77 days, 79.37±0.64, 53.18±0.21’g, 4220.67±35.74 g, 2.74±0.05 eggs, 1.97±0.08 days, 81.04±0.60 %, 59.65±0.76 % and 72.86±0.64 % respectively. Results pointed out that the effect of hatch within generation was significant (P<0.01) on the BW20, BW40, AFE, EW40, EN40, EM40, CS, PS, PF, TES and FES. The heritability of growth traits, production traits and reproduction traits ranged from 0.14±0.06 to 0.23±0.08, 0.22±0.08 to 0.32±0.11 and 0.15±0.29±0.07 respectively. Low to moderate estimates of heritability for growth and production traits and moderate estimates of heritability for reproduction traits indicated that these traits can be improved through family selection.

Detection of genomic signatures of recent selection in commercial broiler chickens.

BackgroundIdentification of the genomic signatures of recent selection may help uncover causal polymorphisms controlling traits relevant to recent decades of selective breeding in livestock. In this study, we aimed at detecting signatures of recent selection in commercial broiler chickens using genotype information from single nucleotide polymorphisms (SNPs). A total of 565 chickens from five commercial purebred lines, including three broiler sire (male) lines and two broiler dam (female) lines, were genotyped using the 60K SNP Illumina iSelect chicken array. To detect genomic signatures of recent selection, we applied two methods based on population comparison, cross-population extended haplotype homozygosity (XP-EHH) and cross-population composite likelihood ratio (XP-CLR), and further analyzed the results to find genomic regions under recent selection in multiple purebred lines.ResultsA total of 321 candidate selection regions spanning approximately 1.45 % of the chicken genome in each line were detected by consensus of results of both XP-EHH and XP-CLR methods. To minimize false discovery due to genetic drift, only 42 of the candidate selection regions that were shared by 2 or more purebred lines were considered as high-confidence selection regions in the study. Of these 42 regions, 20 were 50 kb or less while 4 regions were larger than 0.5 Mb. In total, 91 genes could be found in the 42 regions, among which 19 regions contained only 1 or 2 genes, and 9 regions were located at gene deserts.ConclusionsOur results provide a genome-wide scan of recent selection signatures in five purebred lines of commercial broiler chickens. We found several candidate genes for recent selection in multiple lines, such as SOX6 (Sex Determining Region Y-Box 6) and cTR (Thyroid hormone receptor beta). These genes may have been under recent selection due to their essential roles in growth, development and reproduction in chickens. Furthermore, our results suggest that in some candidate regions, the same or opposite alleles have been under recent selection in multiple lines. Most of the candidate genes in the selection regions are novel, and as such they should be of great interest for future research into the genetic architecture of traits relevant to modern broiler breeding.Electronic supplementary materialThe online version of this article (doi:10.1186/s12863-016-0430-1) contains supplementary material, which is available to authorized users.

Inter- and intra-genetic diversity in the Polish Konik horse: implications for the conservation program

The main objective of the study was to determine the genetic diversity in the Polish Konik (PK) population in the context of a currently conducted conservation program. A total of 94 horses of 16 PK dam lines currently distinguished by breeders were considered. Pedigree analyses were carried out for the whole population of PK registered in the studbook. Basic molecular parameters were estimated. The average group linkage clustering method was used based on the Euclidean similarity measurements between the lines. The allele frequency of 17 microsatellites was used to determine Euclidean distances. Inbreeding coefficients were extracted from the additive relationship matrix. Moreover, some pedigree parameters were estimated. The observed heterozygosity ranged from 0.48 to 0.76. The expected heterozygosity estimated for the dam lines was higher. PIC values were higher than 0.6 in all the lines. Fis ranged from –0.19 to 0.28, whereas Fit and Fst varied between 0.12 and 0.41 and 0.12 and 0.29, respectively. Minor dissimilarity distances existed for some dam lines. The inbreeding level was 9.3%. The average number of discrete generation equivalents reached 6.85. The majority of the dam lines are not genetically differentiated. Hence, a revision of the breeding strategy seems to be necessary.

After genome-wide association studies: Gene networks elucidating candidate genes divergences for number of teats across two pig populations1

Number of teats (NT) is an important trait affecting both piglet's welfare and the production level of pig farms. Biologically, embryonic mammary gland development requires the coordination of many signaling pathways necessary for the proper development of teats. Several QTL for NT have been identified; however, further analysis is still lacking. Therefore, gene networks derived from genomewide association study (GWAS) results can be used to examine shared pathways and functions of putative candidate genes. Besides, such analyses may also be helpful to understand the genetic diversity between populations for the same trait or traits. In this study, we identified significant SNP for Landrace-based (line C) and Large White-based (line D) dam lines. Besides, gene-transcription factor (TF) networks were constructed aiming to obtain the most likely candidate genes for NT in each line followed by a comparative analysis between both lines to access similarities or dissimilarities at the marker and gene level. We identified 24 and 19 significant SNP (Bayes factor ≥ 100) for lines C and D, respectively. Only 1 significant SNP overlapped both lines. Network analysis illustrated gene interactions consistent with known mammal's breast biology and captured known TF. We observed different sets of putative candidate genes for NT in each line evaluated that may have common effects on the phenotype. Based on these results, we demonstrated the importance of post-GWAS analyses increasing the biological understanding of relevant genes for a complex trait. Moreover, we believe that this genomic diversity across lines should be taken into account, considering breed-specific reference populations for genomic selection.

Genetic analysis of growth traits in the progeny of rabbit does from a diallel cross

An experiment was carried out to estimate the genetic group effects and the crossbreeding genetic parameters of growth traits [body weight (BW), average daily gain (ADG), feed intake (FI) and feed conversion ratio (FCR)] in rabbits during fattening between 28 and 63 d. The rabbits were the progeny of does coming from a full diallel cross between 4 maternal lines (A, V, H and LP) mated to bucks of the paternal line R. On thousand fifty five rabbits were controlled and the traits were recorded weekly, with the cage as the experimental unit for FI and FCR (283 cages). The genetic group (V line) was present in all farms in order to connect records among them and to be used as reference group. Crossbreeding parameters were estimated according to the Dickerson model. Regarding dam effects between pure lines for BW at weaning, A line was the heaviest and showed significant differences with LP and V lines (61 and 30 g, respectively). Upon completion of the fattening period, the differences in favour of A line for BW at weaning were compensated. Throughout the fattening period, no significant differences were observed between the lines as dam lines. At the end of the fattening period, no significant differences were observed between the crossbred groups. Regarding the reciprocal effects, the most relevant results were the significances for FCR in favour of H as sire line. For all traits, the confidence intervals at 95% of all contrast and effects were large. The estimates of maternal heterosis were, in general, negative, which could be a consequence of the positive heterosis for litter size. The AH cross showed significant maternal heterosis for BW at 43 d (–53 g), ADG between 28 and 42 d (–3.5 g/d), FI between 28 and 63 d (–7 g/d) and FCR between 42 and 63 d (–0.15). The combination of direct and maternal effects of the V line was the worst for all growth traits, showing significant differences with the LP line for most of them, for instance 0.13 worse FCR between 28 and 63 d. Grand-maternal effects were less important than direct-maternal.

Genome-wide association study reveals regions associated with gestation length in two pig populations.

Reproduction traits, such as gestation length (GLE), play an important role in dam line breeding in pigs. The objective of our study was to identify single nucleotide polymorphisms (SNPs) that are associated with GLE in two pig populations. Genotypes and deregressed breeding values were available for 2081 Dutch Landrace-based (DL) and 2301 Large White-based (LW) pigs. We identified two QTL regions for GLE, one in each population. For DL, three associated SNPs were detected in one QTL region spanning 0.52Mbp on Sus scrofa chromosome (SSC) 2. For LW, four associated SNPs were detected in one region of 0.14Mbp on SSC5. The region on SSC2 contains the heparin-binding EGF-like growth factor (HBEGF) gene, which promotes embryo implantation and has been described to be involved in embryo survival throughout gestation. The associated SNP can be used for marker-assisted selection in the studied populations, and further studies of the HBEGF gene are warranted to investigate its role in GLE.

Exploring transcriptomic diversity in muscle revealed that cellular signaling pathways mainly differentiate five Western porcine breeds.

BackgroundAmong transcriptomic studies, those comparing species or populations can increase our understanding of the impact of the evolutionary forces on the differentiation of populations. A particular situation is the one of short evolution time with breeds of a domesticated species that underwent strong selective pressures. In this study, the gene expression diversity across five pig breeds has been explored in muscle. Samples came from: 24 Duroc, 33 Landrace, 41 Large White dam line, 10 Large White sire line and 39 Piétrain. From these animals, 147 muscle samples obtained at slaughter were analyzed using the porcine Agilent 44 K v1 microarray.ResultsA total of 12,358 genes were identified as expressed in muscle after normalization and 1,703 genes were declared differential for at least one breed (FDR < 0.001). The functional analysis highlighted that gene expression diversity is mainly linked to cellular signaling pathways such as the PI3K (phosphoinositide 3-kinase) pathway. The PI3K pathway is known to be involved in the control of development of the skeletal muscle mass by affecting extracellular matrix - receptor interactions, regulation of actin cytoskeleton pathways and some metabolic functions. This study also highlighted 228 spots (171 unique genes) that differentiate the breeds from each other. A common subgroup of 15 genes selected by three statistical methods was able to differentiate Duroc, Large White and Piétrain breeds.ConclusionsThis study on transcriptomic differentiation across Western pig breeds highlighted a global picture: mainly signaling pathways were affected. This result is consistent with the selection objective of increasing muscle mass. These transcriptional changes may indicate selection pressure or simply breed differences which may be driven by human selection. Further work aiming at comparing genetic and transcriptomic diversities would further increase our understanding of the consequences of human impact on livestock species.Electronic supplementary materialThe online version of this article (doi:10.1186/s12864-015-2259-9) contains supplementary material, which is available to authorized users.

Evidence for Sire, Dam, and Family Influence on Operant Learning in Horses

To evaluate potential sire and dam effects on learning performance in horses, 102 ponies ranging in age from 47 days to 17 years received a single standard positive reinforcement–based operant “target training” session in their home environment. These animals were from a semi-feral herd of known parentage that had had standard minimal previous handling. Based on quantitative measures of latency to reach criterion and rate of correct responses, subjects were ranked into five levels of learning efficiency. Learning efficiency levels of various sire lines (sires and their offspring), dam lines (dams and their offspring), and sire/dam lines (mating pairs and their full sibling offspring) were compared. Learning efficiency level differed significantly among certain sire lines, dam lines, and sire/dam lines (P < .05, median test). Learning efficiency level also tended to differ among age groups as well as between males and females. Frustration/avoidance response frequency during training was negatively associated with learning efficiency and differed among sire and dam lines. Frustration/avoidance response frequency during training also differed significantly among age groups but not among males and females. These data provide evidence of sire, dam, and sire/dam effects on learning performance in horses in simple operant tasks analogous to those inherent in the training of domestic horses.

Sex without sex chromosomes: genetic architecture of multiple loci independently segregating to determine sex ratios in the copepod Tigriopus californicus.

Sex-determining systems are remarkably diverse and may evolve rapidly. Polygenic sex-determination systems are predicted to be transient and evolutionarily unstable, yet examples have been reported across a range of taxa. Here, we provide the first direct evidence of polygenic sex determination in Tigriopus californicus, a harpacticoid copepod with no heteromorphic sex chromosomes. Using genetically distinct inbred lines selected for male- and female-biased clutches, we generated a genetic map with 39 SNPs across 12 chromosomes. Quantitative trait locus mapping of sex ratio phenotype (the proportion of male offspring produced by an F2 female) in four F2 families revealed six independently segregating quantitative trait loci on five separate chromosomes, explaining 19% of the variation in sex ratios. The sex ratio phenotype varied among loci across chromosomes in both direction and magnitude, with the strongest phenotypic effects on chromosome 10 moderated to some degree by loci on four other chromosomes. For a given locus, sex ratio phenotype varied in magnitude for individuals derived from different dam lines. These data, together with the environmental factors known to contribute to sex determination, characterize the underlying complexity and potential lability of sex determination, and confirm the polygenic architecture of sex determination in T. californicus.

Accuracy of genome-enabled prediction exploring purebred and crossbred pig populations.

Pig breeding companies keep relatively small populations of pure sire and dam lines that are selected to improve the performance of crossbred animals. This design of the pig breeding industry presents challenges to the implementation of genomic selection, which requires large data sets to obtain highly accurate genomic breeding values. The objective of this study was to evaluate the impact of different reference sets (across population and multipopulation) on the accuracy of genomic breeding values in 3 purebred pig populations and to assess the potential of using crossbreed performance in genomic prediction. Data consisted of phenotypes and genotypes on animals from 3 purebred populations (sire line [SL] 1, = 1,146; SL2, = 682; and SL3, = 1,264) and 3 crossbred pig populations (Terminal cross [TER] 1, = 183; TER2, = 106; and TER3, = 177). Animals were genotyped using the Illumina Porcine SNP60 Beadchip. For each purebred population, within-, across-, and multipopulation predictions were considered. In addition, data from the paternal purebred populations were used as a reference set to predict the performance of crossbred animals. Backfat thickness phenotypes were precorrected for fixed effects and subsequently included in the genomic BLUP model. A genomic relationship matrix that accounted for the differences in allele frequencies between lines was implemented. Accuracies of genomic EBV obtained within the 3 different sire lines varied considerably. For within-population prediction, SL1 showed higher values (0.80) than SL2 (0.61) and SL3 (0.67). Multipopulation predictions had accuracies similar to within-population accuracies for the validation in SL1. For SL2 and SL3, the accuracies of multipopulation prediction were similar to the within-population prediction when the reference set was composed by 900 animals (600 of the target line plus 300 of another line). For across-population predictions, the accuracy was mostly close to zero. The accuracies of predicting crossbreed performance were similar for the 3 different crossbred populations (ranging from 0.25 to 0.29). In summary, the differences in accuracy of the within-population scenarios may be due to line divergences in heritability and genetic architecture of the trait. Within- and multipopulation predictions yield similar accuracies. Across-population prediction accuracy was negligible. The moderate accuracy of prediction of crossbreed performance appears to be a result of the relationship between the crossbreed and its parental lines.

A pedigree-based analysis of mitochondrial DNA diversity in a dog population on the example of German Hovawarts

Abstract. The purpose of the article is to illustrate the use of pedigree analysis to evaluate mtDNA diversity in a selected population of pedigree dogs, to describe the paths of mtDNA inheritance and to estimate the spread of potential pedigree errors or mutations that occurred in different generations of ancestors. Hovawart, old German breed, was used as an example. The number and frequencies of mtDNA haplotypes were calculated based on numbers of dam lines and their representatives. The scale of potential errors in calculations that can result from pedigree errors or from new mutations in ancestors from the 5th or 10th ancestral generation was evaluated. The analysis included 368 breeding bitches from four German kennel organizations. The bitches represented three dam lines, with the Ho1, Ho2 and HoU mtDNA haplotypes. Significant differences in the frequency of the haplotypes in the population, from 0.27 to 73.37 %, and among kennel organizations and regions of the country were recorded. Considerable differences in the scale of potential errors in calculations arising from mtDNA mutations or pedigree errors were noted between 0.27 and 28.69 %, depending on the number of representatives of the subline in which the error appeared and the generation taken into account in the simulations. The study revealed an interesting paradox: although the differences between the haplotypes are the result of events (mutations) from thousands of years ago, the number and the frequencies of the haplotypes in the population are the result of the modern history of the population and current breeding policy.

Optimizing selection with several constraints in poultry breeding.

Poultry breeding schemes permanently face the need to control the evolution of coancestry and some critical traits, while selecting for a main breeding objective. The main aims of this article are first to present an efficient selection algorithm adapted to this situation and then to measure how the severity of constraints impacted on the degree of loss for the main trait, compared to BLUP selection on the main trait, without any constraint. Broiler dam and sire line schemes were mimicked by simulation over 10 generations and selection was carried out on the main trait under constraints for coancestry and for another trait, antagonistic with the main trait. The selection algorithm was a special simulated annealing (adaptative simulated annealing (ASA)). It was found to be rapid and able to meet constraints very accurately. A constraint on the second trait was found to induce an impact similar to or even greater than the impact of the constraint on coancestry. The family structure of selected poultry populations made it easy to control the evolution of coancestry at a reasonable cost but was not as useful for reducing the cost of controlling evolution of the antagonistic traits. Multiple constraints impacted almost additively on the genetic gain for the main trait. Adding constraints for several traits would therefore be justified in real life breeding schemes, possibly after evaluating their impact through simulated annealing.

The inclusion of Duroc breed in maternal line affects pork quality and fatty acid profile

The aim of this study was to evaluate the effect of including different percentages of Duroc (D) breed in maternal line [Landrace (LR)×Large White (LW); LR×(LW×D); LR×D] and gender on meat quality and intramuscular (IMF) and subcutaneous (SCF) fatty acid composition. No significant differences were found among dam lines in ultimate pH, L* values and drip and cooking losses. There were higher percentages of saturated fatty acids in LR×D and LR×(LW×D) lines and higher percentages of polyunsaturated fatty acids in LR×LW line in IMF and SCF. Also, LR×D line produced pork with a lower Warner–Bratzler shear force values and higher IMF content and potential of lipid oxidation. Furthermore, the L*, a* and b* values and drip loss were greater in pork from entire males than females. The IMF and SCF of females were more monounsaturated and less polyunsaturated than those from entire males.

Genetic analysis of within-litter variation in piglets' birth weight using genomic or pedigree relationship matrices.

The objective of this study was to estimate the genetic variance for within-litter variation of birth weight (BW0) using genomic (GRM) or pedigree relationship matrices (PRM) and to compare the accuracy of estimated breeding values (EBV) for within-litter variation of BW0 using GRM and PRM. The BW0 and residual variance of BW0 were modeled by the double hierarchical generalized linear model using GRM or PRM. Data came from 2 dam lines: Landrace and Large White. After editing, the data set in Landrace consisted of 748 sows with 1,938 litters and 29,430 piglets and in Large White of 989 sows with 3,320 litters and 51,818 piglets. To construct GRM, 46,466 (Landrace) and 44,826 (Large White) single nucleotide polymorphisms were used, whereas to construct PRM, 5 generations of pedigree were used. The accuracy of EBV with GRM was estimated with 8-fold cross-validation and compared to PRM. Estimated variance components were highly similar for GRM and PRM. The maternal genetic variance in residual variance of BW0 in Landrace was 0.05 with GRM and 0.06 with PRM. In Large White these were 0.04 with GRM and 0.05 with PRM. The genetic coefficient of variation (GCV SDe) was about 0.10 in both dam lines. This indicates a change of 10% in residual SD of BW0 when achieving a genetic response of 1 genetic standard deviation. The genetic correlation between birth weight and its residual variance was about 0.6 in both dam lines. The accuracies of selection for within-litter variation of birth weight were 0.35 with GRM and 0.23 with PRM in Landrace and 0.29 with GRM and 0.34 with PRM in Large White. In this case, using GRM did not significantly increase accuracies of selection. Results, however, show good opportunities to select for reduced within-litter variation of BW0. Genomic selection can increase accuracy of selection when reference populations contain at least 2,000 sows.

Calcium dependent or independent pathway for antibody response against sheep red blood cells in various indigenous and imported breeds of chicken

Birds (433), 7-week-old, of both sexes belonging to Indian native breeds including Aseel, Kadakanath, Naked Neck and Frizzle fowl along with the exotic breeds like Dahlem red, White Leghorn, Synthetic Dam Line (SDL) and Naked Neck broiler were utilized to test the complement response (expressed as CH50 unit/ml) to sheep erythrocytes determined by means of both calcium dependent pathway or classical pathway (CPW) and calcium independent pathway or alternate pathway (APW). The effect of genotype (breed), sex and their interactions on antibody response was also studied. The results revealed the presence of natural CPW and APW antibodies on day of immunization in all groups under study irrespective of sex. The natural APW response was highest in Aseel and lowest in broilers. The highest CPW responses were observed in Dahlem red and Aseel followed by Kadakanath, Naked Neck, White Leghorn, Frizzle, SDL broiler and NN broiler on day 5 p.i. Aseel had the highest level followed by Kadakanath, but Dahlem Red showed much regressed value on day 12 p.i. and also on day 19 p.i. In all the genetic lines peak response was observed on 5th day p.i. and declined thereafter. Aseel, which showed highest response on day 5 p.i. for APW response also had the highest value on day 12 p.i. and 19 p.i. and lowest response was observed in broilers. Males excelled the females for APW response at all days of measurements post immunization in all genetic groups except Dahlem Red and NN broiler on 12&lt;supth/sup&gt;, day p.i. Statistical analysis revealed significant variation in CPW and APW response among the various genetic groups and this remained consistent in all days of post immunization i.e. on day 0,5,12,19 p.i. Sex effects were not significant in any days of p.i. for C.P.W response. Sex effects were significant on days 12 and 19 p.i. only. However, interaction between breed and sex were significant on days 5, 12, and 19 p.i. for CPW and for APW, on days 0 and 19 p.i. It is concluded that the chicken populations utilized in this study differed widely with respect to their immunocompetence traits, on different days of post SRBC injection and observed higher antibody than young birds.

Sustainable crossbreeding systems of beef cattle in the era of climate change

Beef cattle are unique, because they not only suffer from climate change, but they also contribute to climate change through the emission of greenhouse gases (GHG). Mitigation and adaptation strategies are therefore needed. An effective way to reduce the carbon footprint from beef cattle would be to reduce the numbers and increase the production per animal, thereby improving their productivity. Sustainable crossbreeding systems can be an effective way to reduce GHG, as it has been shown to increase production. There are a wide range of different cattle breeds in South Africa which can be optimally utilized for effective and sustainable crossbreeding. This paper reports on the effects of crossbreeding on the kilogram calf weaned per Large Stock Unit (kgC/LSU) for 29 genotypes. These genotypes were formed by crossing Afrikaner (A) cows with Brahman (B), Charolais (C), Hereford (H) and Simmentaler (S) bulls and by back-crossing the F1 cows to the sire lines. A LSU is the equivalent of an ox of 450 kg with a daily weight gain of 500 g on grass pastures with a mean digestible energy (DE) content of 55% and a requirement of 75 MJ metabolizable energy (ME). Crossbreeding with A as dam line increased the kgC/LSU on average by 8 kg (+6%) - with the CA cross producing the most kgC/LSU (+8%) above that of the AA. The BA dam in crosses with C, H and S, increased kgC/LSU on average by 26 kg (+18%) above that of the AA dam, with the H x BA cross, producing the most kgC/LSU (+21%). The BA, CA, HA and SA F1 dam lines, back-crossed to the sire line breeds, increased kgC/LSU on average by 30 kg (21%), 21 kg (15%), 19kg (13%) and 26 kg (18%) above the that of the AA, respectively. The big differences between breeds in kgC/LSU provide the opportunity to facilitate effective crossbreeding that can be useful in the era of climate change. From this study it is clear that cow productivity can be increased by up to 21% through properly designed, sustainable crossbreeding systems, thereby reducing the carbon footprint of beef production.Keywords: Carbon footprint, cow productivity, kilogram calf, production systems