Breeding goats for meat production: 2. Crossbreeding and formation of composite population

This review, the second in the series on breeding goats for meat production, examines the role of crossbreeding and composite population in improving economically important traits necessary for commercial production of meat goats. In general, the crossbreeding of indigenous goats or established breeds with one or more breeds (Alpine, Beetal, Boer, Jamunapari, Nubian and Saanen) that have demonstrated genetic merit in the performance traits of economical importance rely on specific cross and back cross to achieve increased productivity. Concurrently, the combining of desirable morphological characteristics and production performance of two or more breeds in composite populations has had considerable success in other livestock and poultry species, invigorating interest in the breeding of meat goats for commercial production. There have been a number of studies, world-wide, on evaluation of indigenous goats or established breeds and their crosses, including crossbreds derived from exotic breeds that are summarized. Furthermore, the Boer breed developed in South Africa has considerable potential for rapid and permanent improvement of meat production from goats, and studies on the Boer-sired crossbred offspring are highlighted.     

Impacts of production conditions on goat milk vitamin,carotenoid contents and colour indices

The content, composition and variation of vitamin compounds in goat milk have been little studied. An experimental design was based on 28 commercial farms, selected considering the main feeding system (based on main forage and especially pasture access), goat breed (Alpine vs Saanen) and reproductive management (seasonal reproduction), in the main French goat milk production area. Each farm received two visits (spring and autumn) that included a survey on milk production conditions and bulk milk sampling. Milk vitamins (A, E, B₂, B₆, B₉, B₁₂) and carotenoid concentrations plus colour indices were evaluated. A stepwise approach determined the variables of milk production conditions that significantly altered milk indicators. The main forage in the diet was the major factor altering goat milk vitamin and carotenoid concentrations and colour indices. Bulk milk from goats eating fresh grass as forage was richer in α-tocopherol (+64%), pyridoxal (+35%) and total vitamin B₆ (+31%), and b* index (characterising milk yellowness in the CIELAB colour space) was also higher (+12%) than in milk from goats eating conserved forages. In milk from goats eating fresh grass, concentrations of pyridoxamine, lutein and total carotenoids were higher than in milk of goats fed corn silage (+24, +118 and +101%, respectively), and retinol and α-tocopherol concentrations were higher than in milk of goats fed partially dehydrated grass (+45 and +55%). Vitamin B₂ concentration was higher in milk of goats eating fresh grass than in milk of goats fed hay or corn silage as forage (+10%). However, bulk milk when goats had access to fresh grass was significantly poorer in vitamin B₁₂ than when fed corn silage (?46%) and in γ-tocopherol (?31%) than when fed conserved forage. Alpine goats produced milk with higher vitamin B₂ and folate concentrations than Saanen goats (+18 and +14%, respectively). Additionally, the milk colour index that discriminates milks based on their yellow pigment contents was 7% higher in milk from Alpine than Saanen herds, but milk from Saanen goats was richer in lutein (+46%). Goat milks were richer in vitamins B₂ and B₁₂ and folates, but poorer in vitamin B₆ in autumn than in spring (+12, +133, +15 and ?13%, respectively). This work highlights that goat milk vitamin and carotenoid concentrations and colour indices vary mainly according to the main forage of the diet and secondly according to the breed and season.     

Effect of the rearing system on financial returns from Murciano-Granadina breed goats

In dairy goats, the kid rearing system can have critical importance in financial returns. Commonly used criteria for the choice of rearing system are not always clear due to the high number of factors involved. The aim of this study was to quantify all those factors to facilitate decision making. So, the effect of two different kid rearing systems, mixed rearing system (MRS) and artificial rearing system (ARS), on milk yield, milk composition and somatic cell count (SCC), milk yield loss at weaning for MRS, kid growth and costs of the different traits on the financial returns in Murciano-Granadina breed goats was studied. Twenty-four goats per group were used. In the MRS, goats reared only one kid, which had free access to goat milk 24 h a day and were weaned at week 6 of lactation, whereas kids in the ARS were separated from their mothers at kidding, colostrum and artificially reared. In both systems, dams were machine-milked once a day throughout lactation and the records took place weekly. Potential milk yield was estimated according to the oxytocin method up to week 12 of lactation, and was similar for both rearing systems, although a 12.3% drop in potential milk yield at weaning was observed for MRS. During the first 6 weeks of lactation, marketable milk was lower for dams in MRS compared to those in ARS (72.1 v. 113.0 l), but similar for the rest of the experiment (101.5 v. 99.4 l, respectively). Marketable milk composition and SCC throughout the 12 weeks of lactation were unaffected by the rearing system. Artificial rearing system entailed an increment in production cost of 22.2€ per kid compared to the rearing by MRS. A similar economic return per goat and kid was obtained from ARS and MRS in this experiment, although, due to one herd’s prolificacy of 1.8, the actual results would be 16.2€ per goat in favour of MRS. The real interest of this experiment may be the possibility of extrapolation to different flocks with diverse levels of milk production, prolificacy and prices and costs for incomes and outputs, to estimate the production system that increases returns. In conclusion, the results showed an increase in the cost of €22.2 per kid bred in the ARS, compared to the MRS, and a final return of 16.2€ per goat in favour of the mixed system.     

Ultrasonic biparietal diameter of second trimester Pygmy goat fetuses

Four does pregnant with seven Pygmy goat fetuses were scanned transabdominally from Day 36 to Day 102 of gestation using a real-time ultrasound 5 MHz linear-array scanhead. Fetal biparietal diameter (BPD) was measured on symmetrical frozen images using internal electronic calipers. The relationship between gestational age (GA) in days and BPD in millimeters in Pygmy goat fetuses is expressed as: [GA = 23.2 + 2.08 BPD]. This equation can assign GA to Pygmy goat fetuses of unknown conception dates and allow confinement of does near kidding for induced or observed parturition. Mean kid birthweight was 2.0 + 0.45 kg SEM. These observations are consistent with relationships which have been determined for Toggenburg, Nubian and Angora goat fetuses.     

Genetic diversity analyses reveal first insights into breed‐specific selection signatures within Swiss goat breeds

We used genotype data from the caprine 50k Illumina BeadChip for the assessment of genetic diversity within and between 10 local Swiss goat breeds. Three different cluster methods allowed the goat samples to be assigned to the respective breed groups, whilst the samples of Nera Verzasca and Tessin Grey goats could not be differentiated from each other. The results of the different genetic diversity measures show that Appenzell, Toggenburg, Valais and Booted goats should be prioritized in future conservation activities. Furthermore, we examined runs of homozygosity (ROH) and compared genomic inbreeding coefficients based on ROH (F_ROH) with pedigree‐based inbreeding coefficients (F_PED). The linear relationship between F_ROH and F_PED was confirmed for goats by including samples from the three main breeds (Saanen, Chamois and Toggenburg goats). F_ROH appears to be a suitable measure for describing levels of inbreeding in goat breeds with missing pedigree information. Finally, we derived selection signatures between the breeds. We report a total of 384 putative selection signals. The 25 most significant windows contained genes known for traits such as: coat color variation (MITF, KIT, ASIP), growth (IGF2, IGF2R, HRAS, FGFR3) and milk composition (PITX2). Several other putative genes involved in the formation of populations, which might have been selected for adaptation to the alpine environment, are highlighted. The results provide a contemporary background for the management of genetic diversity in local Swiss goat breeds.     

Fertility of fresh and frozen-thawed goat semen during the nonbreeding season

A total of 4109 does of a local Greek breed (Capra prisca) were synchronized with intravaginal MPA-sponges and PMSG, and 24 bucks of Alpine (n = 8), Saanen (n = 8) and Damascus (n = 8) breeds were used for studying the fertility of nonfrozen and frozen-thawed semen during the nonbreeding season (June to August). Artificial insemination (AI) was performed once (50 to 55 h after sponge withdrawal) or twice (36 and 60 h after sponge withdrawals with fresh semen (collected during the nonbreeding season, stored at 16 degrees C and inseminated within 6 h) or frozen semen (prepared from the same bucks during the preceding breeding season). The induction of estrus was successful, varying between 91.0 and 95.0%. The form of semen (fresh or frozen-thawed used for inseminating the synchronized does affected their fertility: the overall kidding rate with fresh semen (65.5%) was higher (P < 0.05) than that with frozen-thawed semen (53.4%). The fertility level was also affected by the number of inseminations performed: the overall kidding rate was significantly higher (P < 0.001) in the does inseminated twice with fresh or frozen-thawed semen (70.4 and 59. 1%, respectively) than in those inseminated only once (48.9 and 44.9%, respectively). Finally, the breed of the buck used for preparing the fresh or the frozen-thawed semen affected the fertility level of the does. The kidding rate was higher in does inseminated with fresh semen prepared from bucks of the Damascus breed than from bucks of Saanen or Alpine breed. However, when frozen-thawed semen was used the kidding rate was lower in does inseminated with semen prepared from bucks of the Damascus breed than from bucks of the Alpine or Saanen breed. It is concluded that the fresh semen of Alpine, Saanen and Damascus breed bucks, born and raised under the climate conditions prevailing in Greece (34 degrees to 41 degrees N), can be used successfully during the nonbreeding season (June to August) for inseminating does.     

Seroprevalence of Neospora caninum in dairy goats from Bahia, Brazil

Sera from 384 dairy goats in nine herds from Bahia State, Brazil, were assayed for Neospora caninum antibodies using an indirect immunofluorescent antibody test (IFAT). Animals were selected and divided in groups by age and breed. Antibodies against N. caninum were found in 15% (58/384) of goats. Serum titers ranged from 1:100 to 1:3200. There was no significant difference between the age groups. Seroprevalence was higher in Alpine breed (24%) than in Saanen (14%) and Nubian (3%) breeds. The 58 N. caninum-positive sera were also tested for Toxoplasma gondii and 71% of the samples reacted solely to N. caninum. These results indicate that N. caninum infection is common in goat herds in Bahia.     

Ear mites from domestic goats in Florida

Ear canals of 284 domestic goats from Florida were examined via swabbing for the presence of ear mites; 57% were infested withPsoroptes cuniculi. Raillietia caprae was recovered from 2 goats in one herd. Breeds examined were Nubian, Alpine, Saanen, Toggenburg, La Mancha, Spanish/ Woods and Pygmy. Goats with dependent ear types were infested more commonly than those with erect ears; no goats with vestigial ears were found to harbor mites. Goats less than 1 year old had a significantly higher mite prevalence than did goats over 1 year of age. Gross lesions were noted in the ear canals of only three individuals.This paper was previously accepted for publication in the journal Goat and Sheep Research prior to that journal's demise.     

Pseudopregnancy and aseasonal breeding in dairy goats: genetic basis of fertility and impact on lifetime productivity

Until recently, the main selection focus in UK dairy goats has been on milk yield. To develop a selection index suitably weighted for a variety of traits, it is important to understand the genetic relationships between production, health and fertility traits. This study focussed on three aspects of reproduction that are of interest to goat breeders. (1) Out of season (OOS) kidding ability: goats are highly seasonal breeders so achieving consistent, year-round dairy production presents a challenge. It may be possible to select for extended or shifted breeding cycles, however, there are no published studies on the genetic basis of seasonal kidding ability, and a genetic correlation with milk production in dairy goats; (2) age at first kidding (AFK): a reduced AFK offers the opportunity for more rapid genetic improvement, as well as reducing the amount of time and resources required to raise the animals to producing age; (3) pseudopregnancy (PPG): as it is difficult to diagnose pregnancy within 30 days of mating, high herd levels of PPG could add a significant delay in breeding replacement animals, or commencing a new lactation. Using records from 9546 goats, the objective of this study was to investigate the genetic relationships between the reproductive traits described above, and the production traits 520-day milk yield (MY520), lifetime milk yield (MYLife) and lifetime number of days in milk (DIMLife). The ‘out of season’ phenotype was defined as week of kidding relative to the 4 weeks of the year where the highest average number of births occur. Incidences of PPG that occurred during the first lactation were used as cases, while goats with none were assigned as controls. Relevant fixed and random effects were fitted in the models. In line with other reproduction traits, heritability estimates were low ranging from 0.08 to 0.11. A negative genetic correlation was found between AFK and MY520 (−0.22±0.10), whereas a positive genetic correlation was found between PPG and DIMLife (0.58±0.11). Pseudopregnancy and OOS were positively genetically correlated (0.36±0.15). All other genetic correlations were very low. The results of this study indicate that selection for the reproductive traits analysed is feasible, without adversely affecting MYLife.     

Breed differences in biparietal diameters of second trimester Toggenbubrg, Nubian and Angora goat fetuses

Seven purebred Toggenburg fetuses in four does, six purebred Nubian fetuses in four does, and eight Angora fetuses in six does were repeatedly measured using transabdominal real-time ultrasound with a 5 MH(z) linear-array transducer from 40 d to 100 d gestational age (GA) and their biparietal diameters (BPD) were determined. For Toggenburg goats the GA = 27.9 + 1.64 BPD; for Nubian goats the GA = 26.8 + 1.74 BPD; for Angora goats the GA = 28.6 + 1.77 BPD. The breed differences in GA for equal BPD are insignificant at the beginning of the second trimester but are +3 d for Nubian and +6 d for Angora fetuses by the end of the second trimester.     

Comparison of Boer, Kiko, and Spanish meat goat does for stayability and cumulative reproductive output in the humid subtropical southeastern United States

ABSTRACT: BACKGROUND: Longevity is the amount of time breeding females stay active in a herd by avoiding death or culling because of illness or reproductive failure. This is a trait of economic relevance in commercial small ruminant breeding herds as it affects lifetime reproductive output. The purpose of this study was to determine if breed of meat goat influences breeding doe survival rates and cumulative reproductive performance under semi-intensive management. RESULTS: Boer (n[THIN SPACE]=[THIN SPACE]132), Kiko (n[THIN SPACE]=[THIN SPACE]92) and Spanish (n[THIN SPACE]=[THIN SPACE]79) does were evaluated for longevity trends and cumulative kid production. The herd was managed on humid subtropical pasture. Does had the chance to complete 2 to 6 production years. Survival curves were analyzed for 2 culling methods. The actual culling practice removed does after two failures to wean a kid. An alternative culling protocol removed doe records after the first failure to wean a kid. Kid production traits analyzed across herd life were the total number of kids weaned and cumulative kid weight weaned to the 2-, 3-, and 5-year stayability endpoints. Most (82 %) doe exits were illness-related under the actual culling method. Reproductive failure represented 51 % of doe exits under the alternative culling protocol. Boer does had greater survival declines (P[THIN SPACE]<[THIN SPACE]0.01) from 2 to 6 years of herd life compared to Kiko and Spanish under both culling protocols. Boer does had lower stayability rates (P[THIN SPACE]<[THIN SPACE]0.01) at each year endpoint for both culling protocols. Under the alternative protocol, over 50 % of Boer does failed to complete 2 years, whereas over 50 % of Kiko and Spanish does successfully completed 4 years. Boer does had lower (P[THIN SPACE]<[THIN SPACE]0.01) total number of kids weaned and cumulative weight weaned through each stayability endpoint compared to Kiko and Spanish. CONCLUSION: Boer does had low stayability and cumulative kid production rates compared to Kiko and Spanish does. Poor health was the primary driver of does exiting the herd. Kiko and Spanish does did not differ for longevity and lifetime performance indicators.     

The relationship of male-male mounting to mate choice and sexual performance in male dairy goats

Rearing of male farm animals in unisexual groups has been implicated as a factor contributing to the failure of many males to breed as adults. The present study examines the relationship of male-male mounting in yearling dairy goats to subsequent mate preferences and sexual performance.Twenty-four sexually inexperienced male dairy goats, representing the Alpine, LaMancha, Saanen and Toggenburg breeds, were observed for male-male mounting in their home enclosure and then tested for mate choice and sexual performance when exposed to male and female (estrous and diestrous) stimulus animals. Their sexual behavior was compared with 7 adult goats with previous breeding experience.In the mate choice-sexual performance tests, 4 sexually inexperienced goats (17%) were sexually inactive, 6 (25%) mounted both male and female stimulus animals and 14 (58%) mounted only the female stimuli. Mate choice and sexual performance of the 20 sexually active males was not related to the number of male-male mounts initiated or the number of different males mounted in their home enclosure. However, the goats that received the greatest number of mounts in their home pen tended to be bisexual (would mount both male and female stimulus animals) in the mate choice tests. Males that were sexually inactive in mate choice-sexual performance tests repeatedly mounted the same male during home pen observations. Except for ejaculation frequency, the sexual performance of the sexually naive and experienced goats was similar. Goats of the Saanen breed were favored recipients of mounts from other males. There was no relationship between the number of male-male mounts performed and received.It was hypothesized that the reproductive failure of many male farm animals reared in all-male groups may be more closely related to the formation of specific sexual attachments to other males rather than the frequency with which they exhibit homosexual behaviors.     

Production systems of Creole goat and their implications for a breeding programme

The Creole goat is a local meat breed well adapted to the tropical environment of Guadeloupe, a French island in the Caribbean. A survey of 47 goat farmers was conducted in May 2008 to describe the Guadeloupean goat farming systems. It was the preliminary step for the implementation of a breeding programme for Creole goats. Farmers had 31 does on average. A small number (4%) kept only Creole goats. Most of them (62%) had a mixed herd of Creole and crossbreds. One-third of them (34%) reared only crossbred goats. Farmers appreciate the rusticity and resistance of the Creole goat but consider its growth as too slow. The most desired traits for goat selection were conformation and growth for males (77% of the answers). These traits were also important for females (30% of the answers). Maternal qualities were also frequently cited (maternal behaviour 23%, reproduction 20% and milk production 17%). Disease resistance was not seen as an important trait (10% and 7% of the answers for bucks and does, respectively). A typology constituted of five groups of farmers was also created. Farmers of three groups were retained to participate at a selection programme. They kept Creole goats and have expressed a strong willingness to join a selection programme. The results of the survey suggest that a breeding programme should mostly focus on the Creole goat as a maternal breed. Real consideration should be given to disease resistance. The Creole goat has indeed a key role to play in the sustainability of local farming systems.     

Genetic polymorphism of αs1- and αs2-caseins in Hungarian Milking Goats

The aim of this study was to perform an initial characterization of milk quality and to determine genetic polymorphism at the CSN1S1 and CSN1S2 locus in two herds of local dairy goats (Hungarian Milking). The fat, protein and lactose level of milk samples in Hungarian Milking Goats were compared to other local goat breeds worldwide and it was concluded that the mean milk production of the Hungarian goats should be improved. The presence of the A, B, C + D, E, F and O alleles of CSN1S1 locus and A + B + C + E, D, F and O alleles of CSN1S2 locus were genotyped for by PCR-AS and PCR-RFLP methods in 103 goats. The strong B allele of CSN1S1 is more frequent in the local Hungarian Milking than in the imported Alpine and Saanen goats. The relatively high incidence of the O allele of CSN1S2 gene is also characteristic for the Hungarian Milking Goats and those special allele distribution patterns could be used to develop selection strategies to breed specialised lines of Hungarian local breeds.     

Novel polymorphisms of goat growth hormone and growth hormone receptor genes and their effects on growth traits

In this study, the polymorphisms of growth hormone (GH) gene 5' promoter region and intron 8, exons 4 and 10 of growth hormone receptor (GHR) gene were analyzed in Xinong Saanen goats (SG) and Boer goats (BG). Two alleles (A and B) and three genotypes (AA, AB and BB) were detected at P1 locus of GH gene, and two alleles (G and T) and two genotypes (GG and GT) were detected at P4 locus of GHR gene by PCR-SSCP analysis. In addition, two single nucleotide polymorphisms (SNPs)-A73C (P1 locus) and G114T (P4 locus), were identified by DNA sequencing. The frequencies of alleles A and B in the two goat breeds were 0.61-0.62, and 0.39-0.38, respectively, and the frequencies of alleles G and T in the two goat breeds were 0.82-0.86, and 0.18-0.14, respectively. The SNP loci were in Hardy-Weinberg disequilibrium in both goat breeds (P<0.05). Polymorphisms of GH and GHR genes were shown to be associated with growth traits in BG breed. AA and GG genotypes were associated with superior growth traits in 1-, 2- and 3-month old individuals. Hence, AA and GG genotypes are suggested to be a molecular marker for superior growth traits in BG breed.     

Genetic and environmental factors that influence production and quality of milk of Alpine and Saanen goats

Data from 1279 lactations of 783 Alpine and Saanen goats of the herd of our university in Minas Gerais, Brazil, were used to study environmental effects on and to estimate genetic parameters for milk production until 270 days of lactation (MP270) and for production and percentages of fat (PFAT and %FAT), protein (PPROT and %PROT), lactose (PLACT and %LACT), and total dry extract (PEXTR and %EXTR). Environmental effects were estimated by a statistical model that included contemporary group effect, type of kidding, genetic grouping, and kidding order. A multi-trait animal model with animal and permanent environment random effects was used to estimate genetic parameters and the significant environmental effects (fixed). Contemporary group influenced all traits; genetic grouping did not influence %LACT; type of kidding did not influence PFAT, %PROT or %LACT, and kidding order did not influence %FAT or %EXTR. Heritability and repeatability estimates were, respectively, 0.19 and 0.37 (MP270); 0.10 and 0.20 (PFAT); 0.12 and 0.24 (PPROT); 0.15 and 0.27 (PLACT); 0.13 and 0.24 (PEXTR); 0.21 and 0.34 (%FAT); 0.39 and 0.44 (%PROT); 0.17 and 0.29 (%LACT); 0.31 and 0.47 (%EXTR). Estimates of genetic correlations among MP270 and production of milk constituents were positive and high, but correlations between MP270 and %FAT, MP270 and %PROT, MP270 and %ESTR were moderate and negative. These heritability estimates show that satisfactory genetic gains can be obtained by selection, especially for milk constituents.     

Efficiency of utilization of high and low quality forage by three goat breeds

Alpine, Angora and Nubian kids, 6–8 months old and weighing 15–25 kg were grazed on high quality (wheat) or low quality pasture (dormant bermudagrass) for 54 d to evaluate breed differences and metabolic responses. Each kid on the bermudagrass pasture also received daily 200 g of a 24% CP supplement to stimulate intake.

Wheat pasture had an in vitro organic matter digestibility (IVOMD) of 78 vs. 35% for the Bermuda pasture. Goats gained 50 g/d on wheat pasture vs. 10 g/d on Bermuda pasture (P<0.02). Angora kids gained the least weight on Bermuda (−8 g/d; P<0.05) and most on wheat pasture (62 g/d; P<0.05). Mohair production was greater for Angora goats on wheat pasture compared to those on Bermuda pastures (9.9 vs. 6.2 g/100 cm²; P<0.05). Angora goats on Bermuda pastures had elevated levels of NEFA and plasma ammonia, and reduced levels of plasma urea N, consistent with catabolism of body tissue stores. Angora goats tended to have lower concentration of rumen VFA and ammonia. Angora goats appear to be more sensitive to inanition as compared to Alpine and Nubian goats. Presumably, their obligate nutrient requirements for hair production limits their ability to adapt, making them more vulnerable to nutritional stress.     

Association of IGF-I gene polymorphisms with milk yield and body size in Chinese dairy goats

The association of IGF-I gene polymorphisms with certain traits in 708 individuals of two Chinese dairy-goat breeds (Guanzhong and Xinong Saanen) was investigated. Polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP) and DNA sequencing methods were employed in screening for genetic variation. Two novel mutations were detected in the 5'-flanking region and in intron 4 of IGF-I gene, viz., g.1617 G > A and g.5752 G > C (accession D26119.2), respectively. The associations of the g.1617 G > A mutation with milk yield and the body size were not significant (p > 0.05). However, in the case of g.5752 G > C, Xinong Saanen dairy goats with the CG genotype presented longer bodies (p < 0.05). Chest circumference (p < 0.05) was larger in Guanzhong goats with the GG genotype. In Xinong Saanen dairy goats with the CC genotype, milk yields were significantly higher during the first and second lactations (p < 0.05). Hence, the g.5752 G > C mutation could facilitate association analysis and serve as a genetic marker for Chinese dairy-goat breeding and genetics.     

Characteristics and seasonal variations in the semen of Alpine, Saanen and Damascus goat bucks born and raised in Greece

Twenty-three purebred Alpine (n=8), Saanen (n=7) and Damascus (n=8) goat bucks raised at the Institute of Reproduction and Artificial Insemination in Thessaloniki, Greece (40 degrees 37 minutes N, 22 degrees 58 minutes E and altitude 32 m above sea level), were used to study the effect of photoperiod on semen production. Samples were collected with an artificial vagina and examined immediately after collection. In spite of the variation in nearly all semen characteristics studied among the 3 breeds of bucks, there was significant seasonal variation in both semen quantity (volume, concentration and total number of spermatozoa per ejaculate) and quality (percentage of motile spermatozoa, percentage of abnormal spermatozoa and rate of progressive motility). The best semen was produced during the breeding season (late summer and autumn). However, the magnitude of these seasonal effects was not sufficient to prevent bucks from being used for breeding throughout the year. Nevertheless, individual differences in the semen quantity and quality among bucks within a breed make individual evaluation of semen necessary to select the most fertile males for breeding.     

Genetic and non-genetic factors related to the success of artificial insemination in dairy goats

The objective of this study was to evaluate genetic and non-genetic factors influencing artificial insemination (AI) success in French dairy goats. Data analysis, on a total of 584 676 and 386 517 AI records for Alpine and Saanen breed, respectively, collected from 1992 to 2009, was conducted separately on each breed. We used a linear simple repeatability animal model which combined male and female random effect and environmental fixed effects. The most important environmental factor identified was the period within year effect due to the European heat wave of 2003. The estimated values of the annual fertility exhibited a negative trend of 1% loss of AI success per 10 years for Alpine breed only. The range of variation for the flock×within years random effect was 70% and 65% for Alpine and Saanen breeds. The negative effect on AI success of antibody production after repetitive hormonal treatment was confirmed. We observed an important positive relationship between fertility and protein yield expressed as quartile within flock×years of protein 250-day yield for female with lactation number over 1, while this trend was negative for primiparous females. We detected a negative effect of the duration of conservation of semen with a difference of about 4% of AI success between extreme values (2 to 8+ or 9+ years). Heritability estimates for male fertility were 0.0037 and 0.0043 for Alpine and Saanen breed respectively, while estimates for female fertility was 0.040 and 0.049. Repeatability estimates for males were 0.008 and 0.010 for Alpine and Saanen, respectively, and 0.097 and 0.102 for females. With such low values of heritability, selection can hardly affect fertility.