Body development in sows, feed intake and maternal capacity. Part 1: performance, pre-breeding and lactation feed intake traits of primiparous sows

Abstract

This study examined the genetic and phenotypic associations between finisher performance, pre-breeding body condition of the gilt, subsequent lactation feed intake and survival of the primiparous sow to farrow in the second parity. Complete data were available on ,2200 sows, along with additional cohort and historical performance data. Genetic variation was observed for average lactation feed intake (heritability: 0.18 6 0.04), with a significant proportion of observed variation in average intake attributable to variation in lactation length. Weight and body condition (fatness) at finishing were very highly correlated genetically (0.89 6 0.03 and 0.90 6 0.02) and moderately correlated phenotypically (0.58 6 0.01 and 0.58 6 0.01) with weight and body condition before mating. Estimates of genetic (r g ) and phenotypic (r p ) correlations between feed intake recorded at finishing and average lactation feed intake (LADI) were moderate (r g 5 0.26 6 0.16 and 0.42 6 0.22) and low (r p 5 0.07 6 0.02 and 0.08 6 0.03), with r g dependent on the models and data subsets used for lactation intake. Non-unity genetic correlations imply that different genetic control mechanisms regulate feed intake during growth and lactation. Moderate genetic correlations between lactation feed intake with live weight (TWT) or growth rate (TADG) recorded at selection and live weight before mating (0.42 6 0.11, 0.42 6 0.11 and 0.37 6 0.15) were considerably higher than the corresponding phenotypic correlations for LADI with TADG or 29WT (0.09 6 0.02 and 0.08 6 0.02). Correlations between fatness at selection (TFAT) or mating (29FT) and LADI were negative but not significantly different from 0. Overall, these data suggest that there is exploitable genetic variation for feed intake during lactation, and that selection is possible if lactation feed intakes are recorded. However, genetic correlations suggest that early growth seems to be related to lactation feed intake capacity. There was generally no strong evidence that selection for lean growth potential in dam lines will substantially diminish sow lactation intake capacity as a correlated response.

Body development in sows, feed intake and maternal capacity. Part 2: gilt body condition before and after lactation, reproductive performance and correlations with lactation feed intake

“…Data for sows that were transferred between units, where farrowing has subsequently been confirmed, were included in this study, in contrast to earlier studies Bunter, 2009). The sow's LADI or LADINS (LADI with shortened lactations removed) (kg/day) was similar to that defined in Lewis and Bunter (2011), the first paper of this series.…”

“…Parameters presented in this study show that factors associated with the current farrowing and lactation event are much more informative in predicting survival to the next parity than previous records (e.g. performance as a finisher, see Lewis and Bunter, 2011), perhaps because of the extremely variable nature of transition characteristics between the two time points. It seems likely that the events surrounding farrowing and lactation have more direct ramifications on survival within the herd, but are not entirely independent of the underlying genetic potential that influences the development of phenotypic characteristics of sows later in life.…”

“…Data characteristics, solutions for systematic effects and heritability estimates for LADI, LADINS and longevity traits were discussed in the previous paper (Lewis and Bunter, 2011), and are not discussed again here.…”

“…Data preparation and analysis Data preparation and preliminary investigations were performed using SAS (SAS, 1999) and described as per Lewis and Bunter (2011). Approximate F-tests were used to assess the significance of systematic effects and/or their interactions.…”

“…Currently published studies suggest that genetic correlations between intake during lactation and sow longevity are more ambiguous than phenotypic results. For example, the results of the study conducted by Lewis and Bunter (2011), Bergsma et al (2008) and Bunter et al (2009) show low genetic correlations between lactation feed intake and longevity. It is possible that considering lactation feed intake in combination with aspects of sow body condition and health will be more informative.…”