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The special topics of the workshop focused on leptin mechanism in ruminant and poultry. One of the essential roles of this hormone is to inform the organism about the level of fat reserves. The leptin gene is expressed in ruminants and poultry adipose tissues. Recent results on variations in plasma leptin and/or levels of leptin mRNA in adipose tissues show positive effects of body fatness and feeding level, and an inhibitory beta-adrenergic effect in cattle. In other respects, in vitro leptin production is stimulated by glucocorticoids and insulin, whose effects are inhibited by growth hormone. Progress in knowledge about leptin will allow to better understand and control the adaptations of energy metabolism and reproductive activity of ruminants to seasonal variations in day length and food supply, as well as variations in carcass fatness of growing animal.

Evaluation of the genetic diversity for six genes in forty animals of the Portuguese indigenous sheep breed (Ovis aries) ""Churra da Terra Quente"" was done. A non-radioactive method to allow single-strand conformation polymorphism (SSCP) detection was optimised, starting from genomic DNA and PCR amplification of seven fragments: exon 1 of the alpha-lactalbumin gene; exons 10 and 11 of the alpha s1-casein gene; exon 7 of the beta-casein gene; exon 4 of the kappa-casein gene; exons 4 and 5 of the growth hormone gene and exon 6 of the growth hormone receptor gene. Polymorphisms were detected in five of the seven PCR products. Only kappa-casein and growth hormone receptor were monomorphic. Alpha-lactalbumin and alpha s1-casein exons showed three conformational patterns, beta-casein and growth hormone exon 4 showed two electrophoretic patterns and growth hormone exon 5 showed five conformational patterns. These data provide evidence that ""Churra da Terra Quente"" has a high genetic variability, which opens interesting prospects for future selection programs and also for preservation strategies. Also, our data show that PCR-SSCP is an appropriate tool for evaluating genetic variability.

Rapid authentification of certified chicken meat: distinguishing slow and fast growing chicken strains using near infrared reflectance spectroscopy. Chicken meat market is characterized by numerous quality marks in Belgium and in Europe: ""Label de Qualite Wallon"" in Belgium, ""Label Rouge"" in France, Labels for geographical origin, organic agriculture, ... The authors have already tested, Near Infrared Reflectance Spectroscopy (NIRS) to authenticate slow growing chicken meats. Their study was extended on a larger set and takes account of special labelling according to European regulation 91/1538/CEE. Our results show that the technique could be integrated in an analytical system of surveillance of slow-growing chicken meat products with quality mark.

Thyroid hormone (TH) receptors preferentially bind 3.5,3'-triiodothyronine (T3). Therefore the metabolism of thyroxine (T4) secreted by the thyroid gland in peripheral tissues, resulting in the production and degradation of receptor-active T3, plays a major role in thyroid function. The most important metabolic pathway for THs is deiodination. Another important pathway is sulfation, which is a reversible pathway that has been shown to interact with TH deiodination efficiency. The enzymes catalysing TH deiodination consist of three types. Type 1 deiodinase (D1) catalyses both outer ring (ORD) and inner ring deiodinalion (IRD). Type II deiodinase (D2) only catalyses ORD while type III (D3) only catalyses IRD. The three chicken deiodinase cDNAs have been cloned recently. These enzymes all belong to the family of selenoproteins. Ontogenetic studies show that the availability of deiodinases is regulated in a tissue specific and developmental stage dependent way. Characteristic for the chicken is the presence of very high levels off, inactivating D3 enzyme in the embryonic liver. Hepatic D3 is subject to acute regulation in a number of situations. Both growth hormone and glucocorticoid injection rapidly decrease hepatic D3 levels, hereby increasing plasma T3 without affecting hepatic D1 levels. The inhibition of D3 seems to be regulated mainly at the level of D3 gene transcription. The effect of growth hormone on D3 expression persists throughout life, while glucocorticoids start to inhibit hepatic D1 expression in posthatch chickens. Food restriction in growing chickens increases hepatic D3 levels. This contributes to the decrease in plasma T3 necessary to reduce energy loss. Refeeding restores hepatic D3 and plasma T3 to control levels within a few hours. It can be concluded that the tissue and time dependent regulation of the balance between TH activating and inactivating enzymes plays an essential role in the control of local T3 availability and hence in TH activity.

Lactoferrin (Lf) is an iron-binding protein found in high concentrations in mammary secretions but synthesized by many tissues. Bovine mammary tissue secretes microg/ml mass of Lf in milk, but during involution and prepartum periods, 20-80 mg per ml concentrations may be observed. While a number of functions have been ascribed to lactoterrin, only the antimicrobial and lymphocyte interactions have compelling experimental evidence of support. We report a new finding that lactoferrin binds to insulin-like growth factor binding protein-3 (IGFBP-3) and not to other mammary secreted IGFBPs (IGFBP-2, -4. and -5). Furthermore, bovine Lf(bLf) is found associated with membranes of mammary cells. We demonstrate that bovine Lf competes with IGF for binding to IGFBP-3 with ED50 competition of 3 microg per ml and displacement of 1 mg per ml to monomeric bLf. The tetrameric form that is favored by high concentrations of Lf and calcium, does not appear to bind IGFBP-3. Both IGFBP-3 and Lf have nuclear localization sequences that are reported to he key components of nuclear localization of proteins. We demonstrate that extracellular IGFBP-3 binds to membrane Lf and that Lf is the key to the entry of IGFBP-3 to mammary cellular nucleus. Additionally, we have shown that the internalization of Lf requires the presence of retinoids that also induces both IGFBP-3 and Lf synthesis in primary cultures of bovine mammary epithelial cells. We hypothesize a new role for Lf in the regulation and integration into the IGF System.

Diversification and inter-species integration in rural livestock system in Burkina Faso. The purpose of this study was to determine the level of existing relation between several animal species bred in extensive livestock systems. Data were collected about breeding importance of cattle, sheep, goat and fowl in four villages of the central region of Burkina Faso (Namanegma, Villy-Moukouan, Luili-Nobere and Yambasse). These villages are located in the Soudano-Sahelian agroclimatic zone. Partial correlation and bivariate ordinary least square methods are computed. The results show that livestock practices are related to diversification and species integration strategies of rural households. That is, many households (16.64/) breed four species together, while 6.14/ of households possess one species. Three and two species breeders account for 14.95 and 14.36/ of households respectively. Poultry represents a driving activity in extensive livestock system. From a social welfare standpoint, fowl activity accounts for 49.42/ of households employment. Cattle breeding is the highest stage in this system and represents a kind ofsocioeconomic prestige for the breeder. The four types of livestock are correlated at different levels. Thus, high correlation degrees are noted between poultry and goat (p > 0.50). On the other hand, there is a weak relation between the remote livestock levels (e.g. poultry and cattle, p < 0.50). These results suggest that incentive policies for livestock must take into account breeders strategies. To promote poultry production can create track down effect on the entire livestock system.

Nine male goats and nine castrated lambs were randomly divided into three groups of six animals to receive one of three experimental diets in a digestion trial. Diet S, provided chopped sorghum straw (SS), 28/ concentrate (C) and 10/ Dolichos lablab hay (D). Diet Su1 provided SS containing 2/ urea, 24/ C and 12/ D, and diet Sue1 provided SS treated to contain 2/ urea and ensiled for 28 days, plus 25/ C and 14/ D. Twenty four lambs were randomly divided into three groups of eight animals to receive one of three diets in a 56-day growth trial; diet S2 provided SS plus 60/ C; diet Su2 provided SS containing 2/ urea plus 60/ C, and diet Sue2 provided SS treated to contain 2/ urea and ensiled for 28 days, plus 60/ C. The digestion trial showed higher (P