Genetic correlations between gestation length, piglet survival and early growth

The objective of the study was to estimate genetic trends from 1977 to 1998 in the French Large White (LW) breed for stillbirth and associated traits measured at farrowing using frozen semen. Two groups of pigs (G77 and G98) were obtained by inseminating LW sows with semen from LW boars born either in 1977 or in 1998. A second generation was produced by inter se mating in each group. Farrowing was thoroughly supervised through both direct observations and video recording all long farrowing on a total of 137 first-and second-parity litters produced by sows from this second generation (68 G77 and 69 G98 litters, respectively). Measurements included birth time, weight and birth characteristics (including orientation, presence of cyanosis or oedema, membrane obstruction, umbilical cord length/content) of each piglet, as well as sow traits (weight and backfat thickness, farrowing duration, litter size and within-litter variation of weights at birth). The data were analysed using linear or generalised linear mixed models, according to the definition of the trait (continuous or binary data). The importance of several effects to piglet probability of stillbirth was then quantified by computing the reduction of variance associated with the addition of each effect in the model. Litter size did not significantly differ in first parity, but was higher in G98 second-parity sows: the differences for global (including pre partum dead piglets) and total numbers of piglets born per litter were 12.3 6 1.1 and 11.3 6 0.6, respectively. G98 sows also had a higher number of stillbirths in both parities (10.7 6 0.3 stillborn per litter). Piglets from G98 litters were heavier at birth (1130 6 40 g for birth weight adjusted for litter size), without any increase in within-litter heterogeneity of birth weight. No significant difference was detected between G77 and G88 groups for farrowing length and the distribution of time interval between piglet births. G98 stillborn piglets had longer and more often empty umbilical cords at birth. G98 piglets born alive also had more often umbilical nodes than G77 piglets. These characteristics were considered as indicators of increased farrowing difficulties and risk of hypoxia at birth in G98 pigs. Time of birth of each piglet, sow fatness at farrowing and time of first placenta expulsion were the main factors of variation of the piglet's probability of stillbirth.

Section: Discussioncontrasting

confidence: 98%

Estimation of genetic trends from 1977 to 1998 for farrowing characteristics in the French Large White breed using frozen semen

Canario

Rydhmer

Gogué³

et al. 2007

“…Heritabilities for NBT in literature have varied considerably, ranging from 0.05 to 0.24 (Serenius et al, 2003;Su et al, 2007;Rydhmer et al, 2008), with most values around 0.10. Moreover, heritabilities of 0.09 for NBA are in accordance with heritabilities for this trait in literature, which range from 0.05 to 0.16 (Rosendo et al, 2007b;Su et al, 2007;Ferná ndez et al, 2008).…”

Section: Reproduction Traitsmentioning

confidence: 99%

“…Several studies over the years looked at the survivability of piglets at birth and from birth till weaning and research has been carried out to determine the heritabilities of traits related to piglet survival (e.g. Rydhmer et al, 2008;Su et al, 2008). These heritabilities are generally low, but the genetic variation is large enough to provide improvement through breeding.…”

Section: Introductionmentioning

confidence: 99%

Estimation of genetic associations between reproduction and production traits based on a sire and dam line with common ancestry

Kapell

Ashworth

Walling

et al. 2009

Genetic parameters for survival, reproduction and production traits were estimated for a sire and dam line, originating from one Large White breed separated more than 25 years ago. The change in parameters due to different selection pressure on reproduction and production traits in both lines was also examined. Data collected between 1990 and 2007 were available for the analysis of reproduction traits in 4713 litters (sire line) and 14 836 litters (dam line) and for the production traits in 58 329 pigs (sire line) and 108 912 pigs (dam line). Genetic parameters were estimated using a Bayesian approach. Average phenotypic differences between lines were substantial with 1.5 more piglets born in the dam line and 1.7 mm less backfat thickness (BF) in the sire line. Based on a multiple trait analysis which included both reproduction and production traits, heritabilities for survival and litter size traits in the sire (or dam) line were estimated at 0.03 6 0.01 (0.06 6 0.01) for percentage of stillborn piglets (SB), 0.10 6 0.03 (0.11 6 0.01) for total number of piglets born (NBT) and 0.09 6 0.03 (0.09 6 0.01) for number of piglets born alive. Heritabilities for production traits were estimated at 0.29 6 0.01 (0.29 6 0.01) for average daily gain, 0.50 6 0.01 (0.42 6 0.01) for BF and 0.41 6 0.01 for muscle depth. Selection pressure on litter size in the dam line resulted in a slightly unfavourable correlation for SB-NBT (0.21 6 0.11), which was only marginally unfavourable in the sire line (0.06 6 0.24). Selection pressure on BF in the sire line may have resulted in the moderately undesirable correlation with SB (20.46 6 0.15), which was not significant in the dam line (20.08 6 0.06). Changing the base population in the dam line to animals born since the year 2000 indicated that selection pressure on different traits has altered the heritabilities and correlations of the traits within the line. The undesirable correlations between survival at birth and reproduction traits or production traits were low so that simultaneous improvement of all traits can be achieved. Heritabilities for survival at birth and reproduction traits were low, but genetic variation was substantial and extensive pedigree information can be used to improve the accuracy of breeding values, so that genetic improvement is expected to be efficient.

“…Criteria include litter weight and uniformity, colostrum and milk production, sow ability to mobilize body reserves, feed intake, scores of maternal behaviour or gestation length (e.g. Valros et al, 2003;Rydhmer et al, 2008;Hellbrü gge et al, 2008a and2008b). Attention should be paid to potential conflicts of resources between piglets and sows.…”

Section: Reproductive Sows and Suckling Pigletsmentioning

confidence: 99%

High physiological demands in intensively raised pigs: impact on health and welfare

Prunier

Heinonen

Quesnel

2010

102

Genetic selection and better control of the environment of the pigs have resulted in increased production levels concerning both reproduction and growth. Such high performances imply high physiological demands that may deteriorate health and welfare. The aims of this paper are to review the physiological challenges that pigs are facing, to identify possible consequences on health and welfare, to propose ways of detecting and correcting problems whenever possible. At weaning, piglets are submitted to abrupt changes in food supply, housing and social environment. Behavioural changes and efficient adaptations of the digestive tract are critical for their health and welfare. Physiological demands to support these adaptations and risks of failure are inversely related to the age of the pigs. During fattening, modern pigs have high daily weight gain especially of lean tissue as well as elevated feed conversion rate. These high growth performances are suspected to favour stress and disease susceptibility, undesirable behaviours as well as leg weakness, but further experimental data are necessary to validate these effects and find their origin. In reproductive females, high prolificacy generates elevated foetal demands for nutrients and space that are not fully met as shown by an increased number of light piglets having difficulties to adapt successfully to the neonatal life. During lactation, sows with high milk production have high nutrient requirements leading to intense catabolism that may affect their health, welfare and future reproductive abilities.