Isabelle Louveau

Influence of age and genotype on endocrine parameters and growth performance: a comparative study in Wild boars, Meishan and Large White boars

Endocrine parameter and growth performance were monitored in chronically cannulated male Meishan (MS; n=11), Large White (LW; n=12) and European wild boars (WB; n=11) between 20 and 52 weeks of age. Food intake was recorded daily and body weight was determined weekly. Metabolic hormones were measured in daily blood samples (IGF-I, gonadal hormones, cortisol) or 12 h window samplings (GH, insulin). LW boars revealed a significantly higher growth performance than the other genotypes (LS mean±S.E.M., gain (g/day); LW: 1101±32; WB: 233±44; MS: 332±50; food/gain: LW: 4.61±0.21; WB: 6.53±0.34; MS: 5.31±0.37). Endocrine differences between genotypes were significant for IGF-I (LW: 228±1.25; WB: 280±1.87; MS: 117±1.28 ng/ml), cortisol (LW: 26.1±0.59; WB: 65.0±0.78; MS: 55.6±0.57 ng/ml) testosterone (LW: 3.12±0.11; WB: 3.27±0.16; MS: 6.02±0.11 ng/ml) and estradiol (LW: 179.7±4.0; WB: 151.7±5.8; MS: 470.1±4.3 pg/ml). Insulin levels were highest in LW (17.5±0.79 μU/ml) and differed significantly from those in MS (10.1±0.59 μU/ml). Thus, it is concluded, that the growth potential of LW is mainly due to low levels of cortisol, whereas the intermediate performance of MS is explained by high levels of anticatabolic androgens, which counteract cortisol but also limit food intake.

Comparative effect of orally administered sodium butyrate before or after weaning on growth and several indices of gastrointestinal biology of piglets

Sodium butyrate (SB) provided orally favours body growth and maturation of the gastrointestinal tract (GIT) in milk-fed pigs. In weaned pigs, conflicting results have been obtained. Therefore, we hypothesised that the effects of SB (3 g/kg DM intake) depend on the period (before v. after weaning) of its oral administration. From the age of 5 d, thirty-two pigs, blocked in quadruplicates within litters, were assigned to one of four treatments: no SB (control), SB before (for 24 d), or after (for 11-12 d) weaning and SB before and after weaning (for 35-36 d). Growth performance, feed intake and various end-point indices of GIT anatomy and physiology were investigated at slaughter. The pigs supplemented with SB before weaning grew faster after weaning than the controls (P < 0.05). The feed intake was higher in pigs supplemented with SB before or after weaning (P < 0.05). SB provided before weaning improved post-weaning faecal digestibility (P < 0.05) while SB after weaning decreased ileal and faecal digestibilities (P < 0.05). Gastric digesta retention was higher when SB was provided before weaning (P < 0.05). Post-weaning administration of SB decreased the activity of three pancreatic enzymes and five intestinal enzymes (P < 0.05). IL-18 gene expression tended to be lower in the mid-jejunum in SB-supplemented pigs. The small-intestinal mucosa was thinner and jejunal villous height lower in all SB groups (P < 0.05). In conclusion, the pre-weaning SB supplementation was the most efficient to stimulate body growth and feed intake after weaning, by reducing gastric emptying and intestinal mucosa weight and by increasing feed digestibility.

Regional differences in porcine adipocytes isolated from skeletal muscle and adipose tissues as identified by a proteomic approach

The content and distribution of body lipids are of special interest for production efficiency and meat quality in the farm animal industry. Triglycerides represent the most variable fraction of tissue lipids, and are mainly stored in adipocytes. Although several studies have reported regional differences in the expression of genes and their products in adipocytes from various species, the characteristics of i.m. adipocytes remain poorly described. To evaluate adipocyte features according to muscle and other fat locations, adipocyte proteins were isolated from trapezius skeletal muscle, and intermuscular, s.c., or perirenal adipose tissues from 6 female pigs (80 d of age). Protein extracts were labeled and analyzed by 2-dimensional, fluorescent, differential gel electrophoresis. The comparisons revealed that 149 spots were always differentially expressed (P < 0.05, ratio exceeding |2|-fold difference) between i.m. adipocytes and the fat cells derived from the 3 other adipose locations. The proteins that were downregulated in i.m. fat cells belonged to various metabolic pathways, such as lipogenesis (cytosolic malate dehydrogenase and isocitrate dehydrogenase, P < 0.01), glycolysis (enolases and aldolase, P </= 0.01), lipolysis (perilipin, P < 0.01), fatty acid oxidation (long-chain fatty-acyl CoA dehydrogenase, P < 0.01), and energy transfer (catalase, voltage-dependent anion channel 1, and electron-transfer flavoprotein, P < 0.05). In contrast, both prohibitin-1 and cell division cycle 42 homolog, with possible roles in cell growth, were up-regulated (P < 0.05) in i.m. adipocytes compared with other fat cells. Fewer differences were observed when adipocytes isolated from s.c., perirenal, and intermuscular fat tissues were compared, with a maximum of 17 spots differing significantly in abundance between perirenal and s.c. adipose tissues. The findings that proteins involved in both anabolic and energy-yielding catabolic pathways are downregulated in i.m. adipocytes compared with s.c., visceral, or intermuscular adipocytes, suggest that the metabolic activity of i.m. adipocytes is low. Thus, triggering adipogenesis rather than cell metabolism per se might be a valuable strategy to control lipid deposition in pig skeletal muscles.

How Muscle Structure and Composition Influence Meat and Flesh Quality.

Skeletal muscle consists of several tissues, such as muscle fibers and connective and adipose tissues. This review aims to describe the features of these various muscle components and their relationships with the technological, nutritional, and sensory properties of meat/flesh from different livestock and fish species. Thus, the contractile and metabolic types, size and number of muscle fibers, the content, composition and distribution of the connective tissue, and the content and lipid composition of intramuscular fat play a role in the determination of meat/flesh appearance, color, tenderness, juiciness, flavor, and technological value. Interestingly, the biochemical and structural characteristics of muscle fibers, intramuscular connective tissue, and intramuscular fat appear to play independent role, which suggests that the properties of these various muscle components can be independently modulated by genetics or environmental factors to achieve production efficiency and improve meat/flesh quality.

Metabolic changes and tissue responses to selection on residual feed intake in growing pigs.

Previous selection experiments using residual feed intake (RFI) to select pigs with a high feed efficiency have reported that a low RFI was associated with a reduced body fat content and a greater muscle glycogen content. In the current study, growing Large White female piglets from 2 lines divergently selected for RFI were used to determine the changes in energy and protein metabolisms in key tissues and their cross talks in response to selection. Pigs of low RFI (RFI(-); n = 26) or high RFI (RFI(+); n = 36) selection lines were offered free access to feed during postweaning and growing periods. Pigs of each line were then slaughtered at 19 kg (n = 8 per line) or 115 kg BW (n = 14 to 18 per line). A third group of pigs of the RFI(+) line was offered feed at the same level per metabolic BW (BW0.60) as RFI- pigs (group RFI+R, n = 14). Regardless of the growth period considered, G:F was less in RFI(+) pigs than in RFI(-) pigs. At 19 kg BW, RFI(+) and RFI(-) pigs had a similar body composition and tissue lipid content. The fractional rate of protein synthesis and proteasome activity were decreased (P < 0.090) in the livers of RFI(+) pigs compared with RFI(-) pigs whereas activities of energy catabolic enzymes did not differ in the liver and LM samples. Plasma insulin was conversely greater (P = 0.049) in RFI(+) pigs at this stage. At 115 kg BW, enzyme activities of protein catabolism in the liver and in the LM did not differ (P > 0.10) between RFI(+) pigs and RFI(-) pigs. Both lactate dehydrogenase activity participating in glucose metabolism and hydroxylacylCoA dehydrogenase activity involved in fatty acid oxidation were greater (P < 0.05) in the liver and LM of RFI(+) pigs compared with RFI(-) pigs. In the liver, contrary to the LM, those differences in enzyme activities were directly associated with selection on RFI regardless of ADFI. Increased backfat depth and content and greater lipid content and adipocyte hypertrophy (P < 0.05) in subcutaneous adipose tissue were reported in RFI(+) pigs compared with RFI(-) pigs at 115 kg BW without marked changes in key lipogenic enzyme activities; these changes were directly associated with ADFI. In conclusion, the present study shows an increase of catabolic pathway activities in the liver and muscle of RFI(+) pigs at market weight that is likely to generate more ATP compared with RFI(-) pigs.

Prenatal exposure to maternal low or high protein diets induces modest changes in the adipose tissue proteome of newborn piglets.

The possibility that maternal diets during gestation could affect growth and tissue development of offspring and program their later phenotype is an emerging challenge in pig production. The objective of the current study was to investigate the effects of contrasted protein levels in diets of pregnant sows on the proteomic features of subcutaneous adipose tissue (SCAT) of the offspring at birth and its possible persistence later in age. Sows were fed control (Con), low (LP), or high protein (HP) diets throughout gestation. A subset of piglets was killed at 1 d of age for SCAT sampling. The remaining piglets were cross-fostered to nonexperimental sows during lactation. They were fed standard diets during postweaning and fattening periods until 186 d of age. Modifications in SCAT protein abundance shortly after birth were investigated by 2-dimensional gel electrophoresis followed by mass spectrometry. A total of 65 spots were found differentially expressed (P <or= 0.10) in SCAT of 1-d-old experimental piglets vs. Con piglets. Proteins with a greater abundance in LP piglets compared with Con piglets were involved in pathways related to glucose and fatty acid metabolisms, lipid transport, and regulation of apoptosis. Upregulation of 5 proteins representative of these biological pathways in LP group vs. Con group were further validated (P < 0.05) by Western blot analyses. Furthermore, the specific activity of the key lipogenic enzyme fatty acid synthase was found greater (P = 0.06) in SCAT of 1-d-old LP piglets than in Con piglets. The main changes evidenced in SCAT of HP piglets compared with Con animals at 1 d of age rather concerned proteins putatively involved in AA metabolism or in protein turnover. Adipose tissue contents in some proteins that had displayed a greater (P <or= 0.10) abundance in experimental pigs compared with Con at d 1 (e.g., transaldolase, annexin II, and apolipoprotein A4) were, however, similar (P > 0.10) in the 3 groups at d 186 of age. Enolase 1 has less abundance (P < 0.05) in LP pigs compared with Con pigs at this stage. In conclusion, the proteomics tool has allowed the identification of early changes in various molecular pathways of SCAT in response to the levels of maternal protein supply during gestation.

Effect of feed restriction on hormones, performance, carcass traits, and meat quality in immunocastrated pigs.

The aim of this study was to assess the effect of feed restriction applied to immunocastrated pigs in the period after the second vaccination (V2) against GnRH on hormonal status, performance, carcass traits, and meat quality. Immunocastrated pigs (IC) were compared with entire males (EM) and surgical castrates fed ad libitum. Pigs (Large White × Landrace) × Pietrain were either left entire or surgically castrated within 1 wk after birth (SC, n = 22). At 83 d of age, the entire males were further allotted to treatment groups (individual housing) of ad libitum fed EM (n = 24), ad libitum fed IC (IC-L, n = 21), or restrictively fed IC (IC-R, n = 21). At that time, the first vaccination (V1) was applied to IC-L and IC-R pigs. One week after V2 (age 130 d), feed restriction (≈ 80% of the ad libitum feed intake of SC pigs) was applied to IC-R pigs. The experiment ended 5 wk after V2, when pigs were 165 d old. Immunocastration successfully reduced boar taint compounds and size of reproductive organs. At 130 d, serum leptin concentrations were similar in all groups, whereas IGF-I concentration was less in SC (P ≤ 0.002) than in the other groups. Three weeks after V2, leptin concentrations of both IC groups were in between EM (least) and SC (greatest). The reverse was observed for IGF-I. Feed restriction had no effect on leptin or IGF-I concentrations in IC pigs. In the period V1 to V2, performance differed mainly between EM and SC, whereas both IC groups had feed intake and feed conversion ratio similar to EM and intermediate daily BW gain, not differing from either EM or SC. After V2, IC-L pigs increased their feed intake to the concentrations of SC, with faster growth compared with the other 3 groups (P < 0.05) and fatter carcasses compared with EM pigs (P = 0.007). Similar performance and carcass leanness were observed for IC-R and EM pigs. During preslaughter handling more carcass lesions were noted in EM and IC-R than in IC-L or SC pigs (P < 0.002). Neither immunocastration nor feed restriction had any effect on meat quality, but EM had greater drip loss, less intramuscular fat, and decreased tenderness than SC pigs. In conclusion, restricting feed intake can increase production efficiency but also aggressiveness of IC pigs.

Impact of intrauterine growth retardation and early protein intake on growth, adipose tissue, and the insulin-like growth factor system in piglets.

Small birth weight and excess of early protein intake are suspected to enhance later adiposity. The present study was undertaken to determine the impact of diets differing in protein content on short-term growth, adipose tissue development, and the insulin-like growth factor (IGF) system in piglets. Normal (NW) and small (SW) birth weight piglets were fed milk-replacers formulated to provide an adequate (AP) or a high protein (HP) supply between 7 and 28 d of age. The fractional growth rate was higher (p < 0.01) in SW than in NW piglets. At 7 d of age, the lower (p < 0.05) weight of perirenal adipose tissue relative to body mass in SW than in NW piglets did not involve significant changes in plasma IGF-I, leptin, or insulin-like growth factor binding protein levels, but involved differences (p < 0.05) in the expression of IGF-I and leptin in adipose tissue. Growth rates did not differ between AP and HP piglets. At 28 d of age, HP piglets had lower (p < 0.001) relative perirenal adipose tissue weight but did not differ clearly from AP piglets with regard to the IGF system. It remains to be determined whether piglets fed such a high protein intake will stay subsequently with a low adiposity.

A computed tomography scan application to evaluate adiposity in a minipig model of human obesity

The aim of the present study was to describe and validate a computed tomography (CT) method to analyse adiposity distribution in Göttingen minipigs. Adiposity was evaluated in two groups of minipigs. In group 1 (n 8), measurements were performed before and after the induction of obesity. In group 2 (n 7), animals were fed rations designed to obtain heterogeneous adiposity before analyses. CT acquisitions were associated with anatomical, ultrasonography and body chemical measurements. Our CT method was based on acquisition of a single slice at a fixed anatomical landmark, calculation of individual X-ray density ranges for CT values and delineation of the three main adipose compartments (subcutaneous adipose tissue, SAT; retroperitoneal adipose tissue, RAT; and visceral adipose tissue, VAT). Our validation measures showed that the CT-scan method was accurate, sensitive and reliable. The CT data were found to be correlated with body weight, abdominal perimeter, ultrasonography, anatomical measurements and body chemical composition (from r 0.84 to 0.93, P < 0.001 for all), with a pitfall concerning the precise estimation of VAT. With increased body weight, the amount of adipose tissue increased and the relative proportion of SAT increased, whereas the relative proportion of RAT and VAT decreased (P < 0.001 for all). Adiposity measured by CT, and especially SAT, was found to be negatively correlated with insulin sensitivity (r 0.54, P < 0.05). In conclusion, a precise evaluation of the adipose compartments in minipigs was done by CT. Therefore, the use of Göttingen minipigs is relevant to further investigate the relationship between the different adipose tissues and obesity.

Growth and development of adipose tissue and gut and related endocrine status during early growth in the pig: impact of low birth weight

With genetic selection, the increase in litter size has led to higher variation in within-litter birth weights in pigs. This has been associated with a reduction in mean birth weights and a rise in the proportion of piglets weighing less than 1 kg at birth. Low birth weight pigs exhibit lower postnatal growth rates and feed efficiency, which may be explained by an inadequate digestion and/or nutrient use as a consequence of prenatal undernutrition. It is now documented that there is a relationship between birth weight and subsequent pattern of growth and development of tissues and organs. During the neonatal period, the rapid somatic growth is accompanied by tremendous anatomical, physiological and chemical composition changes. The present review focuses primarily on the influence of low birth weight on adipose tissue and the gastrointestinal tract growth and development during the suckling period. The importance of the somatotropic axis, insulin, thyroid hormones, glucocorticoids, epidermal growth factor and leptin in the regulation of these developmental processes is also considered.