Yves Beckers

Efficiency of a Lactobacillus plantarum-xylanase combination on growth performances, microflora populations, and nutrient digestibilities of broilers infected with Salmonella Typhimurium

Three experiments were performed to assess the ability of a Lactobacillus plantarum probiotic combined with a xylanase to reduce the effects of Salmonella Typhimurium infection in broiler chickens from 1 to 30 or 42 d of age. Chicks were challenged at 3 d of age with 10(8) or 10(5) cfu Salmonella Typhimurium/chick. Four diets were studied: a wheat-based diet (C+) supplemented with 0.1 g/kg of xylanase (E) or 10(6) cfu/g of L. plantarum (P), or both (PE). Uninfected chicks fed the C diet were used as negative control (C-). Six or 8 chicks were housed per cage with 9 cages/treatment. Growth performance and feed conversion ratio (FCR) were recorded weekly. In experiment 1, bacterial enumeration in ceca was achieved using the fluorescent in situ hybridization technique. Salmonella enumeration was realized in excreta by microbiological cultures (experiments 2 and 3). Nutrient digestibilities and AME(n) were determined in experiment 3 from d 35 to 39. Infection with Salmonella Typhimurium led to a significant decrease in the daily weight gain (DWG) by 23.6 to 32.8%, whereas FCR was increased by 1.0 to 19.7%. Chickens fed the PE diet showed significantly improved performance in comparison with C+ birds (DWG: +12.5% in experiment 1; FCR: -2.1 to 8.6%), and in comparison with the P and E treatments (DWG: +6.3 to 8.3% in experiment 1; FCR: -2.7 to 6.4%). In experiment 3, the FCR was significantly improved by 3% with the PE diet in comparison with C- chickens. The PE combination tended to restore a microflora similar to that of uninfected broilers, whereas the P and E diets had less of an effect on the profile of bacterial communities. At slaughter age, Salmonella contamination was reduced by 2.00 and 1.85 log colony-forming units for the E and PE treatment, respectively. The PE diet significantly reduced the crude fat digestibility by 9.2%, in comparison with the C+ chickens. These results suggest that the combination between L. plantarum and a xylanase as feed additive could be effective for reduction of the detrimental effect after Salmonella Typhimurium infection of broilers.

Effects of level of intake and of available volatile fatty acids on the absorptive capacity of sheep rumen

The objective of this experiment was to determine t he respective effects of level of intake and of the amount of volatile fatty acids (VFAs) present in the rumen on VFA ruminal absorption. In a factorial design, six ewes received a hay diet either at 126 or at 73% of ener gy maintenance requirements. Their capacity of abso rption of VFAs was evaluated by the method of temporarily isolated rumens, in which the rumen was filled with so lutions containing high or low amounts of VFAs. Rate of absorption (amount of VFAs absorbed per hour) was significantly higher, by 32% on average, in sheep f ed the high intake than in sheep fed at low intake. The proportion of initial VFAs absorbed did not depend on the concentration of VFAs introduced in the rume n, so that the amount of VFAs absorbed varied as the conc entration of VFAs introduced in the rumen. The decr ease in intake resulted in a decrease by 32% in the rate of absorption of total VFAs. No interaction between concentration of VFAs and previous intake was obser ved. This suggests that the capacity of the rumen t o absorb VFAs is reduced at low intake even if low amounts o f VFAs are available.

Intestinal digestibility of rumen undegraded N of concentrates measured by the mobile nylon bag technique

Two experiments were carried out on sheep to measure the effects of some factors of the mobile nylon bag (MNB) technique on the intestinal digestibility (DgI) of rumen undegraded N of meat and bone meal (MBM), soybean meal (SBM) and wheat bran (WB). The pore size of the nylon cloth (10 and 42.5 μm) influenced (P 0.05). Increasing incubation times in the rumen decreased (P < 0.05) DgI of undegraded feed N. The total tract digestibility (rumen plus intestines) was independent of incubation time in the rumen for MBM and SBM, excepted for SBM incubated 4 or 8 h in the rumen when bags were collected in the ileum. Previous ruminal incubation of WB for 4, 8, 16 and 24 h increased (P < 0.05) the amount of N digested in the total tract in comparison with unincubated WB and WB incubated for only 2 h. In the second experiment, residues obtained from the incubation of the feeds in the rumen (0, 2, 4, 8, 16, 24 and 48 h) were mixed in different proportions in order to obtain the true fraction of the undegraded feed in the rumen. This method was based on the DM degradability of the concentrate feeds and the outflow rate constant of feeds from the rumen, supposed equal to 6% h−1. Bags containing feeds mixed according to this method were incubated in a solution of pepsin-HCl for 0, 1, 2 and 3 h to simulate abomasal digestion and the DgI of N was measured afterwards with the MNB technique. Increasing action of pepsin led to higher digestibilities of N at this stage (P < 0.05) but decreased the digestibility of N in the intestines excepted for MBM incubated in pepsin-HCl for 3 h and in any case for SBM. However, the omission of the incubation in pepsin had little influence on the amount of N postruminally digested.

Effects of the nature of nitrogen supplementation on voluntary intake, rumen parameters and ruminal degradation of dry matter in sheep fed oat silage-based diets

The effects of nature of nitrogen supplementation on silage DM intake (SDMI), total DM intake (TDMI), rumen parameters and ruminal degradation of DM of silage and wheat straw were studied using four adult Noire de Thibar rams. Silage was made from predominantly oats harvested at milk stage and ensiled without preservative. The silage was offered ad libitum as the sole diet (OS) or supplemented with 450 g DM of iso-nitrogen (25.6 g/kg DM) and iso-energy (0.8 Unite Fourragere Lait: UFL/kg DM) concentrate containing soybean meal (SBM), urea (UR) or poultry litter (PL) as nitrogen supplements. SDMI (g/kg W 0.75 × day) and TDMI (g/kg W 0.75 × day) were affected ( P< 0.001) by the type of supplement and averaged 63.9, 60.1, 54.9, 51.1 and 63.9, 81.4, 74.8, 72.2 for OS, SBM, PL and UR diets, respectively. In comparison with other diets, SBM diet systematically decreased ( P< 0.05) the pH of the rumen after the morning feeding and reduced the rumen concentration of total VFA at 1 h after feeding. SBM diet decreased DM disappearance of the oat silage incubated in nylon bags for 72 h ( P< 0.05), but not of wheat straw. The three supplements increased the ammonia-N concentrations in the rumen for several hours after feeding in comparison with the OS diet. However, only the SBM diet kept this difference just before the next meal. It is concluded that despite its low nutritive value (0.62 UFL and 108 g crude protein/kg DM), the oat silage is well consumed by the local ruminants accustomed to use poor forages for a long time. In Tunisia, poultry litter may be used as a nitrogen source to supplement the oat silage for sheep.

Determination Of The Methionine Requirement Of Finishing Double-Muscled Belgian Blue Bulls With A Three-Step Method

Une methode en trois etapes a ete utilisee pour determiner le besoin en acides amines (AA) totaux et celui du premier AA limitant chez les taurillons Blanc Bleu Belge culards (BBBc) en periode de finition.Dans une premiere experience, trois taurillons BBBc (505 ′ 21 kg) ont recu une ration pauvre en proteines digestibles se composant de 25% de foin de prairie et de 75% de concentre. Lapport denergie nette etait satisfaisant pour maximiser le croit quotidien grâce a la perfusion continue de dextrose dans le duodenum. La digestibilite intestinale apparente des AA essentiels atteignait en moyenne 70.8% et variait de 61.3% pour lhistidine a 79.9% pour larginine. Dans une seconde experience, quatre taurillons BBBc (517 ′ 16 kg) ont recu la meme ration accompagnee dune perfusion duodenale de dextrose et de quatre doses de caseinate de Na (17, 33, 50 et 66% des AA digestibles dans lintestin grele fournis par la ration epreuve) selon un carre latin 4 x 4. La retention azotee pour la ration de base seule et les quatre complements de caseinate de Na a atteint respectivement 61, 64, 74, 75 et 78 g j - 1 . Un apport de 720 g j - 1 dAA digestibles a ete defini comme optimalisant lutilisation de lN pour la croissance des animaux. Sur base des concentrations plasmatiques, la methionine et la phenylalanine etaient probablement les AA limitants. Dans une troisieme experience, cinq taurillons BBBc (513 ′ 60 kg) nourris avec la ration epreuve, ont recu une perfusion duodenale de dextrose et dAA equivalente a la dose optimale definie dans la seconde experience a lexception de lapport de methionine digestible (12.8, 15.1, 17.6, 20.1, 22.6 et 25.1 g j - 1 ) variant selon un dispositif experimental en carre latin 6 x 6 avec un animal manquant. Sur base de la retention azotee, le besoin en methionine digestible a ete estime a 22.8 g j - 1 et correspondait a 360 mg de methionine digestible par gramme dazote retenu.