Herve Lagant

Detection of quantitative trait loci for growth and fatness in pigs.

A quantitative trait locus (QTL) analysis of growth and fatness data from a three-generation experimental cross between Meishan (MS) and Large White (LW) pig breeds is presented. Six boars and 23 F1 sows, the progeny of six LW boars and six MS sows, produced 530 F2 males and 573 F2 females. Nine growth traits, i.e. body weight at birth and at 3, 10, 13, 17 and 22 weeks of age, average daily gain from birth to 3 weeks, from 3 to 10 weeks and from 10 to 22 weeks of age, as well as backfat thickness at 13, 17 and 22 weeks of age and at 40 and 60 kg live weight were analysed. Animals were typed for a total of 137 markers covering the entire porcine genome. Analyses were performed using two interval mapping methods: a line-cross (LC) regression method where founder lines were assumed to be fixed for different QTL alleles and a half-/full-sib (HFS) maximum likelihood method where allele substitution effects were estimated within each half-/full-sib family. Both methods revealed highly significant gene effects for growth on chromosomes 1, 4 and 7 and for backfat thickness on chromosomes 1, 4, 5, 7 and X, and significant gene effects on chromosome 6 for growth and backfat thickness. Suggestive QTLs were also revealed by both methods on chromosomes 2 and 3 for growth and 2 for backfat thickness. Significant gene effects were detected for growth on chromosomes 11, 13, 14, 16 and 18 and for backfat thickness on chromosome 8, 10, 13 and 14. LW alleles were associated with high growth rate and low backfat thickness, except for those of chromosome 7 and to a lesser extent early-growth alleles on chromosomes 1 and 2 and backfat thickness alleles on chromosome 6.

Correlated responses in sow appetite, residual feed intake, body composition, and reproduction after divergent selection for residual feed intake in the growing pig

Residual feed intake (RFI) has been explored as an alternative selection criterion to feed conversion ratio to capture the fraction of feed intake not explained by expected production and maintenance requirements. Selection experiments have found that low RFI in the growing pig is genetically correlated with reduced fatness and feed intake. Selection for feed conversion ratio also reduces sow appetite and fatness, which, together with increased prolificacy, has been seen as a hindrance for sow lifetime performance. The aims of our study were to derive equations for sow RFI during lactation (SRFI) and to evaluate the effect of selection for RFI during growth on sow traits during lactation. Data were obtained on 2 divergent lines selected for 7 generations for low and high RFI during growth in purebred Large Whites. The RFI was measured on candidates for selection (1,065 pigs), and sow performance data were available for 480 sows having from 1 to 3 parities (1,071 parities). Traits measured were sow daily feed intake (SDFI); sow BW and body composition before farrowing and at weaning (28.4 ± 1.7d); number of piglets born total, born alive, and surviving at weaning; and litter weight, average piglet BW, and within-litter SD of piglet BW at birth, 21 d of age (when creep feeding was available), and weaning. Sow RFI was defined as the difference between observed SDFI and SDFI predicted for sow maintenance and production. Daily production requirements were quantified by litter size and daily litter BW gain as well as daily changes in sow body reserves. The SRFI represented 24% of the phenotypic variability of SDFI. Heritability estimates for RFI and SRFI were both 0.14. The genetic correlation between RFI and SRFI was 0.29 ± 0.23. Genetic correlations of RFI with sow traits were low to moderate, consistent with responses to selection; selection for low RFI during growth reduced SDFI and increased number of piglets and litter growth, but also increased mobilization of body reserves. No effect on rebreeding performance was found. Metabolic changes previously observed during growth in response to selection might explain part of the better efficiency of the low-RFI sows, decreasing basal metabolism and favoring rapid allocation of resources to lactation. We propose to consider SRFI as an alternative to SDFI to select for efficient sows with reduced input demands during lactation.

Neonatal mortality in piglets: genetics to improve behavioural vitality

Maternal abilities and piglet vitality were analyzed on 24 Meishan (MS) and 24 Large White (LW) gilts. Females were inseminated with a mixture of semen from both breeds. Three MS and 3 LW boars were used to constitute 3 duos formed by mixing of MS and LW semen in equal proportions. Farrowing events were studied over 5 successive batches. The proportion of purebred and crossbred piglets within the litter varied according to the duo used and the dam breed (p<0.01). The average within-litter percentage of purebred piglets in LW and MS sows was respectively 43% and 50% with use of duo 1, 64% and 23% with duo 2 and 69% and 81% with duo 3. Gestation was shorter in MS than in LW sows (111.6 vs 114.0 days; p<0.05) and litter size tended to be larger in LW than in MS sows (14.6 vs 12.8 total born piglets; p=0.08). Over the three first days of lactation, piglet probability of survival was similar between purebred and crossbred piglets born from LW sows (94.5% vs 95.0%) and higher in purebred than crossbred piglets born from MS sows (96.6% vs 98.7%, p<0.05). In LW sows, crossbred piglets were heavier at birth and more reactive in a novel environment than purebred piglets (1.29 vs 1.21 kg, p<0.10; reactivity score: 1.38 vs 1.03 respectively). In MS sows, purebred piglets had a lower birth weight than crossbred piglets but showed similar vitality (0.86 vs 1.08 kg, p<0.001; reactivity score: 1.00 vs 1.03). Birth process and piglet behavior in early lactation will be analyzed to estimate the interaction between dam breed and piglet genetic type (purebred vs crossbred) on the expression of maternal behavior and piglet vitality (udder activity and survival).Young horses normally live in small year-round stable groups including one stallion, their mothers, a few other mares, their siblings and unrelated peers. On the contrary, most of young domestic horses are generally maintained in same-age and same-sex groups from weaning until training. One has to consider that the absence of adult partners during ontogeny may be a source of behavioral disorders. In a first study, we focused on social conditions at weaning. While it is well known that presence of peers is of high importance to alleviate weaning stress, we investigated here the effects of the introduction of unrelated adult mares in groups of weanlings. Results showed that signs of stress were less pronounced and shorter in time in weanlings housed with adult mares than in weanlings kept in same-age groups (e.g. distress vocalizations: P<0.05; salivary cortisol: P<0.05). Besides, only foals deprived of adult presence exhibited increased aggressiveness towards peers (P<0.05) and abnormal behaviors (P<0.05). In conclusion, the presence of two unrelated adults in groups of weanlings not only alleviated weaning stress, but also favored positive social behavior and limited the emergence of abnormal behaviors. In a second study, we examined the impact of the temporary presence of adult horses on the behavior of 1- and 2-year-old horses. Results showed that young horses reared in homogeneous groups had a reduced behavioral repertoire, no real preferred partner and displayed many agonistic interactions compared to domestic horses reared under more natural conditions. Interestingly, after the introduction of adults, young horses expressed new behaviors (e.g. snapping, lying recumbent), preferential social associations emerged (P<0.05) and positive social behavior increased (P<0.05). Taken together, these results have important implications in terms of husbandry, indicating the importance of keeping young horses with adults.The aim of this work was to characterise the European consumer of pig meat (within ALCASDE project). A total of 822 respondents participated in a survey that was carried out Germany (DE n=132), Spain (ES n=133), France (FR n=139), Italy (IT n=140), Netherlands (NL n=132) and United Kingdom (UK n=146). All of them were selected for consuming pork > 1 time/month and stratified by age and gender, within each country profile. Respondents answered socio-demographic questions and frequency of consumption of different pork products, the most common purchasing place for fresh pork meat, if they were responsible for buying fresh pork at home, if they were responsible for cooking at home, and if they usually eat the pork with the fat. Data was analysed with FREQ procedure of SAS software. In general, over ninety percent of consumers ate fresh pork > 2 times/week (DE 96.2 %; ES 95.5 %; IT 92.9 %; NL 93.9 %; UK 97.3 %) except for FR (34.8 %). The most consumed product was the sausage in DE, dry cured ham in ES and IT; cooked ham in FR, mince meat in NL and sliced bacon in UK. In all the countries, the supermarket was the most common purchasing place of fresh pork with the exception of NL, where it was the traditional market. In general, the percentage of respondents responsible for buying fresh pork in their household was 91.0 %. In all countries, women were more responsible for buying fresh pork than men, and they were mostly between 41-60 years old. Ninety-one percent of respondents were partially responsible for cooking at home. Women were more responsible for cooking at home than men. France was an exception, where 49.6 % women and 50.4 % men cooked at home. Considering all respondents, 44.5 % ate the pork with the fat in all the countries (35.4 % of women and 54.6 % of men). The study showed differences among countries regarding respondents’ traits.