Effects of photoperiod and feeding level on adipose tissue and muscle lipoprotein lipase activity and mRNA level in dry non-pregnant sheep

Abstract

The aim of the present study was to investigate the effects of photoperiod and feeding level on lipid metabolism in ovine perirenal and subcutaneous adipose tissues (AT) and in skeletal and cardiac muscles. Twenty dry non-pregnant ovariectomised ewes were divided into two groups and subjected to either 8 h or 16 h light/d, and underfed at 22 % energy requirements for 7 d. Half of the ewes in each group were slaughtered and the remaining ewes were refed at 190 % energy requirements for 14 d, until slaughtering. Refeeding increased (2´6±4´3-fold) malic enzyme (ME), fatty acid synthase (FAS), glucose-6-phosphate dehydrogenase (G6PDH) and glycerol-3-phosphate dehydrogenase (G3PDH) activities in subcutaneous AT as well as lipoprotein lipase (LPL) activity in perirenal (3´5-fold) and subcutaneous (10-fold) AT and to a lesser extent (1´4-fold) in the skeletal longissimus thoracis and cardiac muscles. Moreover, variations of LPL mRNA level followed variations of LPL activity: refeeding increased perirenal AT-and cardiac muscle-mRNA levels (7´4-and 2-fold respectively). The main finding of this study is that, for a given level of food intake, long days (compared with short days) increased the LPL activity in the longissimus thoracis muscle and, in refed ewes, the activities of LPL and ME in subcutaneous AT. Furthermore, long days increased LPL mRNA level in cardiac muscle and perirenal AT. Thus, our results show that there are direct effects of photoperiod on sheep AT lipogenic potential, as well as on muscle LPL activity, which are not caused by changes in nutrient availability.

Seasonality of reproduction and production in farm fishes, birds and mammals

“…Chemineau, Malpaux, Brillard, Fostier (Auchtung et al, 2005). These effects cause a modulation of milk secretion at the mammary gland level, probably via pituitary hormones like prolactin and its associated receptors in the mammary tissue (Auchtung et al, 2005) but also via a general orientation of the metabolic routes under photoperiodic entrainment (Bocquier et al, 1998;Faulconnier et al, 2001;Chilliard and Bocquier, 2000;Chilliard et al, 2005). Photoperiod has also been shown to modify the general immune system in dairy cattle (Auchtung et al, 2004).…”

Traitements photopériodiques et reproduction chez les animaux d'élevage

“…Au contraire, des vaches soumises à des jours courts pendant leur période de tarissement, produisent plus de lait lors de la lactation suivante, lorsqu'elles sont maintenues ultérieurement sous photopériode normale (Auchtung et al 2005). Ces traitements produisent une modulation de la sécrétion lactée résultant probablement de celle de la sécrétion d'hormones comme la prolactine et/ou de la synthèse de ses récepteurs par les cellules acineuses mammaires (Auchtung et al 2005) ; une ré-orientation générale des voies métaboliques peut être également induite par l'entraînement photopériodique (Faulconnier et al 2001 ;Chilliard et al 2005).…”

Carcass traits of Nellore, F1 Simmental × Nellore and F1 Angus × Nellore steers fed at maintenance or ad libitum with two concentrate levels in the diet

“…Nonetheless, differences were observed (P<0.05) for LMA/100 kg of carcass where F 1 Simmental × Nellore animals presented greater values than F 1 Angus × Nellore cattle, which presented greater RFT values (P<0.05) ( Table 4). Feijó et al (1997), in a study with Simmental × Nellore cattle observed an increase of carcass length of crossbred animals. Vaz & Restle (2001) have found greater values of carcass length in crossbred animals, evidentiating the heterosis of the characteristic.…”

“…Differences in carcass yield between genetic types are commonly seen when the time of slaughter is determined by the evaluation of carcass finishing score (Euclides filho et al, 1997), as the some animals can presented the desired finishing score at heavier weights and consequently greater carcass yield. Thus, animals with lighter BW at maturity may present high carcass finishing score and consequently higher carcass yield.…”

“…Several genes related to structural proteins and enzymes have their expression reduced when the animal is submitted to a feedrestriction, as the energy is mostly used for maintenance of vital functions rather than tissue deposition. According to Faulconnie et al (2001), feed-restricted animals present a reduction of expression of the lipoprotein lipase, responsible for lipid deposition into the adipocytes. This is a possible explanation for the production of carcass with larger amount of muscles and lower amount of fat in feed-restricted animals.…”