Phenotypic and genetic relationships between growth and feed intake curves and feed efficiency and amino acid requirements in the growing pig

Abstract

Improvement of feed efficiency in pigs has been achieved essentially by increasing lean growth rate, which resulted in lower feed intake (FI). The objective was to evaluate the impact of strategies for improving feed efficiency on the dynamics of FI and growth in growing pigs to revisit nutrient recommendations and strategies for feed efficiency improvement. In 2010, three BWs, at 35 ± 2, 63 ± 9 and 107 ± 7 kg, and daily FI during this period were recorded in three French test stations on 379 Large White and 327 French Landrace from maternal pig populations and 215 Large White from a sire population. Individual growth and FI model parameters were obtained with the InraPorc ® software and individual nutrient requirements were computed. The model parameters were explored according to feed efficiency as measured by residual feed intake (RFI) or feed conversion ratio (FCR). Animals were separated in groups of better feed efficiency (RFI − or FCR − ), medium feed efficiency and poor feed efficiency. Second, genetic relationships between feed efficiency and model parameters were estimated. Despite similar average daily gains (ADG) during the test for all RFI groups, RFI − pigs had a lower initial growth rate and a higher final growth rate compared with other pigs. The same initial growth rate was found for all FCR groups, but FCR − pigs had significantly higher final growth rates than other pigs, resulting in significantly different ADG. Dynamic of FI also differed between RFI or FCR groups. The calculated digestible lysine requirements, expressed in g/MJ net energy (NE), showed the same trends for RFI or FCR groups: the average requirements for the 25% most efficient animals were 13% higher than that of the 25% least efficient animals during the whole test, reaching 0.90 to 0.95 g/MJ NE at the beginning of the test, which is slightly greater than usual feed recommendations for growing pigs. Model parameters were moderately heritable (0.30 ± 0.13 to 0.56 ± 0.13), except for the precocity of growth (0.06 ± 0.08). The parameter representing the quantity of feed at 50 kg BW showed a relatively high genetic correlation with RFI (0.49 ± 0.14), and average protein deposition between 35 and 110 kg had the highest correlation with FCR (−0.76 ± 0.08). Thus, growth and FI dynamics may be envisaged as breeding tools to improve feed efficiency. Furthermore, improvement of feed efficiency should be envisaged jointly with new feeding strategies.Keywords: growth curve, pig, residual feed intake, amino acid requirements, feed efficiency Implications Improving feed efficiency in growing pigs by increasing lean growth rate has resulted in a decreased feed intake (FI). It also impacted the dynamics of FI and growth. Amino acid requirements larger than usual feed recommendations were estimated at the beginning of the growing period for the most efficient animals. In addition, parameters from growth and FI models showed good genetic properties with respect to FI and efficiency. Feeding strategies need to be adjusted to cover the requireme...

Finishing pigs that are divergent in feed efficiency show small differences in intestinal functionality and structure

“…Correspondingly in the present study, pigs selected for low and high RFI had higher ADFI and RFI values from low to high RFI across locations in the present study. Differences in pigs’ age, type of diets, management, selection strategies for RFI and breeds used may help explain discrepancies observed when the results from previous studies are compared, as these studies were limited to one batch of pigs or to a single rearing location [2–5,12,13]. In order to enhance the current knowledge about the RFI-related variation in the size, structure and functionality of the GIT in pigs, we therefore designed pig trials across three geographical locations to mirror each other as closely as possible.…”

“…Moreover, the mucosal integrity is important to consider with respect to translocation of intestinal antigens, thereby triggering energetically costly immune responses and affecting growth efficiency [5,7]. Previous findings for RFI-related differences in GIT size, innate immune response and digestive efficiency in pigs were equivocal [2–5, 12,13]. Some studies reported an enhanced ileal digestibility of energy and expression of SGLT1 and GLUT2 in the jejunum of growing pigs [3,14], whereas other did not find RFI-related differences for digestive efficiency [2,12].…”

“…To date, most research regarding the impact of the gastrointestinal tract ( GIT ) on variation in RFI has been conducted under controlled conditions in one environment [2–4,13], whereby differences in environment, pig age, diet type and selection strategies for RFI used in the different studies may explain the controversial findings [15]. Therefore, we hypothesized that if the size, structure and functionality of the GIT play a role in variation of the RFI in pigs, similar RFI-relationships should be found in low and high RFI pigs which were raised under similar conditions in several environments.…”

Proteomic analysis indicates that mitochondrial energy metabolism in skeletal muscle tissue is negatively correlated with feed efficiency in pigs

“…FE is a complex economic trait that is known to be correlated with many biological factors. In pigs, the growth rate and skeletal muscle content have been reported to be positively related to the FE trait56 Further, the fat content and physical activity have been found to be negatively related to the FE trait78.…”

Sélection pour la consommation alimentaire moyenne journalière résiduelle chez le porc : impacts sur les caractères et défis pour la filière

“…Le paramètre représentant la CMJ à 50 kg de poids vif a été identifié comme un prédicteur précoce possible de la CMJR : il est héritable (h² = 0,41) et a une corrélation génétique de 0,61 avec la CMJR. Des différences de cinétiques ont aussi été rapportées dans les lignées divergentes américaines, en particulier pendant la phase tardive de croissance (Cai et al , 2012, et dans les lignées commerciales françaises (Saintilan et al 2015). Ainsi, la sélection pour la CMJR modifie les dynamiques d'ingestion des porcs, ainsi que leurs besoins nutritionnels au cours de la période d'engraissement.…”