Maryline Kouba

Comparative study of in vitro lipogenesis in various adipose tissues in the growing domestic pig (Sus domesticus).

Activities of acetyl-CoA-carboxylase, malic enzyme and glucose-6-phosphate-dehydrogenase were measured in seven different anatomical sites in the growing pig (20-120 kg weight). The three enzyme activities increased up to 40-60 kg weight and then decreased, malic enzyme becoming the main producer of NADPH, irrespective of the adipose tissue. Subcutaneous adipose tissue of the neck area was much thicker and exhibited much lower lipogenic enzyme activities than backfat. Subcutaneous adipose tissue is heterogeneous in the pig with some areas exhibiting very low lipogenesis and high lipid deposition importing triglycerides from other areas with high lipogenesis. However, these conclusions based on the measurement of enzyme activity potentials need to be confirmed with measurements of actual activities.

Quantification of muscle, subcutaneous fat and intermuscular fat in pig carcasses and cuts by magnetic resonance imaging

The aim of this study was to determine the suitability of magnetic resonance imaging (MRI) to predict tissue composition of pig carcasses and cuts. Twenty-four pig carcasses were cut into the four primary cuts that were analyzed with a low field MRI imager before a total dissection. Images were then processed to identify and quantify pixels representing muscle, subcutaneous fat and intermuscular fat fractions. MRI provided a good prediction of muscle content in cuts and carcasses, with R(2) ranging from 0.970 to 0.997. The prediction was slightly less accurate for total fat (0.951⩽R(2)⩽0.986) or subcutaneous fat (0.918⩽R(2)⩽0.994). Finally, the prediction of intermuscular fat content in considering intermuscular fat classified pixels was acceptable only for the belly (R(2)=0.837).

Effect of a linseed diet on lipid composition, lipid peroxidation and consumer evaluation of French fresh and cooked pork meats.

Twenty castrated pigs [(Large-White×Landrace)×(Pietrain)] (52.9±5.1kg initial body weight) were fed a control or a linseed diet containing 4.2% of extruded linseed. Animals were slaughtered at 106.6±3.7kg live weight. There was no effect of diet on pig performance. Feeding the linseed diet increased the contents of n-3 polyunsaturated fatty acids (PUFA) in chops (raw and cooked), chitterlings sausages, country style pâté, garlic sausages, liver pâté, and smoked belly. However, docosahexaenoic acid (DHA) level was not affected by the linseed diet. The linseed diet produced a robust decrease in the n-6/n-3 and linoleic acid (LA)/α-linolenic acid (ALA) ratios (<4). Feeding pigs with a high n-3 PUFA diet led to a decrease in the oxidative stability of chops, in contrast to smoked bellies for which thiobarbituric acid-reactive substances (TBARS) values were not affected by the diet. However, there was no deleterious effect on consumer overall appreciation of the meat.

Effect of a high linoleic acid diet on lipogenic enzyme activities and on the composition of the lipid fraction of fat and lean tissues in the pig

The aim of this study was to examine the influence of a high linoleic acid diet on lipogenic enzyme activities in pig tissues and on the dietetic quality of these tissues (subcutaneous adipose tissue, Semimembranosus and Diaphragma muscles). Pigs were fed diet M containing 4% of maize oil or diet T containing 4% of tallow from 40 to 100 kg live weight. We did not observe any differences in growth or slaughter performances that could be attributed to diet. Lipogenic enzyme activities were higher in the adipose tissue of pigs fed diet M. However, diet had no effect on lipogenesis in the muscles. The lipid, linoleic acid, and cholesterol contents were higher in the adipose tissue of pigs fed diet M whereas the oleic acid concentration of the adipose tissue was lower. No significant increase in the lipid content of either muscle was however observed in pigs fed diet M. The linoleic acid and cholesterol contents were higher in both muscles of pigs fed diet M than in muscles of pigs fed diet T.

Consequences of divergent selection for residual feed intake in pigs on muscle energy metabolism and meat quality

Selection to decrease Residual Feed Intake (RFI) is a relevant way to improve feed efficiency in growing pigs. However, RFI criterion is correlated with body composition and muscle characteristics. Present study evaluated adaptive responses to divergent selection on RFI on muscle metabolism and homeostasis through AMP-activated protein kinase pathway. Consequences on technological and sensory meat quality were also analyzed in two lines of Large White pigs after six generations of divergent selection on RFI. RFI(-) pigs (n=60) exhibited similar growth rate but lower feed intake and conversion ratio, and were leaner than RFI(+) pigs (n=57). Despite higher glycogen content, metabolic enzyme capacities involved in glycolytic, fatty acid oxidation pathway and energy balance were reduced in the Longissimus muscle of the RFI(-) pigs. Reduced muscle homeostasis in the RFI(-) line influenced post-mortem metabolism and impaired technological quality traits of loin and ham but had only slight effects on meat eating quality.

Influence of a high ambient temperature on stearoyl-CoA-desaturase activity in the growing pig.

An experiment was conducted to determine the influence of a high ambient temperature on the stearoyl-CoA-desaturase activity and fatty acid composition of backfat, leaf fat, Longissimus dorsi muscle and liver, in the growing pig. Eighteen Large White X Landrace castrated pigs (20 kg body weight) were divided into three groups: I (31 degrees C, ad libitum), II (20 degrees C, pair-fed on the 31 degrees C group) and III (20 degrees C, ad libitum) until 35 kg body weight. At 20 degrees C, the level of feed intake had no effect on stearoyl-CoA-desaturase activity, whatever the tissue (groups II and III). At similar levels of feeding, (groups I and II), the stearoyl-CoA-desaturase activity was lower at 31 degrees C (P < 0.001) than at 20 degrees C, regardless of the tissue, with the exception of the hepatic stearoyl-CoA-desaturase activity, which was similar in all three groups. This reduction of the stearoyl-CoA-desaturase activity at 31 degrees C could be related to a decrease in the monounsaturated fatty acid percentage in all the tissues, in hot conditions. The present results show that changes in fatty acid composition caused by environmental temperature, in the pig, may be attributed at least in part to an alteration in the stearoyl-CoA-desaturase activity.

A review of the factors influencing the development of intermuscular adipose tissue in the growing pig

Compared with subcutaneous or abdominal fat depots of pig carcasses, intermuscular fat displays a number of original properties. It cannot be easily removed from fresh or processed meat delivered to consumers and has therefore an influence on consumer acceptability of pork. Particular compositional characteristics of intermuscular fat include low lipid content and small size of adipocytes. How age (or body weight), gender, castration, environmental temperature, feeding restriction, diet composition, as well as genetic factors affect intermuscular fat development and composition are surveyed in this review paper. Up to now, few studies have specifically dealt with the intermuscular compartment of body fat while very abundant information is available on the subcutaneous one. As a general rule, any factor, either genetic or non-genetic, which causes a decrease of whole carcass fat deposition generates a higher relative importance of the intermuscular fraction of total fat as well as an increased degree of unsaturation of constituent fatty acids.

Effect of dietary fats on hepatic lipid metabolism in the growing turkey

The influence of dietary fatty acids on hepatic capacity of lipid synthesis and secretion was investigated in 7-week-old male turkeys. They were fed 10% of either lard (rich in saturated and monounsaturated fatty acids) or linseed oil (rich in polyunsaturated fatty acids, especially 18:3n-3). Fattening was identical with both diets (0.15-0.20% of abdominal adipose tissue), but the proportion of muscle Pectoralis major was lower with linseed oil (6.6 vs. 7.4%). Specific activities of lipogenic enzymes (ME, G6PDH, ACX, and Delta9-desaturase) were not influenced by the diet, however, FAS activity was lower with linseed oil (14.3 vs. 25.4 nM NADPH fixed/min). Fasting concentrations of lipoproteins synthesized and secreted by the liver, VLDL and HDL, were also lower with linseed oil, as well as plasma concentrations of phospholipids and cholesteryl esters. However, when VLDL catabolism was inhibited by injection of an antiserum against LPL, VLDL concentration was identical in both groups (100-120 mg/l), whereas that of phospholipids and cholesteryl esters, that are transported by HDL mainly, remained lower with linseed oil. Thus, in the growing turkeys, and contrary to mammals and the chicken, feeding n-3 polyunsaturated fatty acids did not decrease hepatic triglyceride synthesis and secretion, nor fattening. By contrast, in this species, n-3 polyunsaturated fatty acids appear to influence mostly HDL metabolism, with a negative impact on muscular growth.

Comparative study of in vitro lipogenesis in various adipose tissues in the growing meishan pig: Comparison with the large white pig (Sus domesticus)

Abstract Activities of acetyl-CoA-carboxylase, malic enzyme and glucose-6-phosphate-dehydrogenase were measured at six anatomical sites in Meishan pigs (20–100 kg weight). Results were compared with data previously obtained in our laboratory in Large White pigs. In Meishan pigs, the enzyme activities generally decreased with weight. Both malic enzyme and glucose-6-phosphate dehydrogenase activities were higher in Meishan pigs than in Large White. Glucose-6-phosphate-dehydrogenase was the main producer of NADPH in Meishan pigs. Acetyl-CoA-carboxylase activity in lighter Meishan animals (

Stearoyl-CoA desaturase activity in adipose tissues and liver of growing Large White and Meishan pigs.

Stearoyl-CoA desaturase activity was measured in adipose tissue (backfat and neckfat) and liver microsomes of Large White and Meishan pigs. Preliminary assays have shown that delta 9-desaturase activity cannot be measured on frozen tissues, because freezing involves a loss in activity of 40-50%. The specific activity of liver delta 9-desaturase was much lower than that of the adipose tissues in both breeds, indicating that the liver is not a major site of oleate synthesis in the pig. The hepatic delta 9-desaturase activity was higher in Meishan than in Large White pigs. However, delta 9-desaturase activity in the adipose tissue of Large White pigs was much higher than that of Meishan pigs, even though the percentage of oleate was slightly higher in the adipose tissues of the latter. This investigation has demonstrated that differences in fatty acid composition of adipose tissues between Large White and Meishan pigs cannot be attributed to differences in delta 9-desaturase activity at this stage of maturity. These results suggest that the higher oleate percentage in Meishan adipose tissues would result from a higher delta 9-desaturase activity at an earlier age.