A trial was conducted to determine the effect of low-protein diets with constant ME:CP ratio on performance and carcass characteristics of broilers from 1 to 35 d of age. Four experimental diets were formulated to have 4 levels of CP and ME, respectively, in each phase: 23, 22, 21, and 20% CP with 3,036, 2,904, 2,772, and 2,640 kcal/kg in the starter phase (1 to 10 d); 22, 21, 20, and 19% CP with 3,146, 3,003, 2,860, and 2,717 kcal/kg in the grower phase (11 to 26 d); and 20, 19, 18, and 17% CP with 3,100, 2,945, 2,790, and 2,635 kcal/kg in the finisher phase (27 to 35 d). Digestible Lys was maintained at 1.10, 1.02, and 0.90% of the diet in the starter, grower, and finisher periods, respectively. A total of 1,760 one-day-old Hubbard broiler chickens were randomly divided into 16 experimental pens, 110 chickens in each pen, and each diet was offered to 4 replicates at random. Weight gain was linearly decreased (P < 0.001), whereas feed intake and feed conversion ratio were increased (P < 0.001) linearly as dietary protein and energy decreased during grower, finisher, and overall experimental periods. Protein efficiency ratio and energy efficiency ratio were decreased (P < 0.05) with low-CP and low-ME diets during the grower, finisher, and overall experimental period. However, carcass yield, breast meat yield, thigh yield, abdominal fat, and relative liver and heart weights were not affected by the treatments. Feeding broiler chickens low-CP diets with constant ME:CP ratio has adversely affected the growth performance, but carcass parameters were unaffected without any increase in abdominal fat content.

Five Holstein cows with ruminal cannulas were used in a 5 x 5 Latin square design to determine the effect of replacing forage NDF with soyhull NDF and varying concentrations of nonstructural carbohydrates on nutrient digestion and milk production. Diets in which NDF percentage from forage (corn silage: alfalfa hay, 1:1) was 80 (control), 70, or 60 were formulated by substituting soyhulls for forage; total forage was 43.2, 36.7, and 31.1% of the diets, respectively, but total NDF was 31%. Nonstructural carbohydrates were formulated to be 47 (control), 35, or 25% by substituting soyhulls, roasted soybeans, and Ca soaps for concentrate. Ruminal acetate: propionate ratio decreased linearly when diets lower in forage NDF were fed, but it increased quadratically when dietary nonstructural carbohydrates were reduced. Apparent digestibility of OM increased quadratically, but NDF digestibility and lactation performance were unaffected when diets lower in forage NDF were fed. Digestibility of NDF increased linearly when nonstructural carbohydrates were reduced, perhaps because of greater digestibility of soyhull NDF and smaller negative associative effects. Fat from soybeans and Ca soaps was increased as nonstructural carbohydrates decreased. Added fat probably increased fatty acid digestibility and decreased milk protein percentage. Greater FCM production without correspondingly greater feed intake or BW loss increased feed efficiency as nonstructural carbohydrates decreased. In dairy rations containing soyhulls, 60% of dietary NDF from forage should maintain lactation performance, and decreasing nonstructural carbohydrates to 25 to 35% of feed DM, coupled with adding dietary fat, may decrease negative associative effects and improve efficiency of milk production.

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One-day-old Starbro male broiler chicks (n = 360) were used to determine the effect of increasing levels of Na+ and Cl- above the NRC (1994) recommendations for growing broilers diets (hatching to 28 d) in extremely hot weather. The average maximum and minimum temperatures recorded were 39 and 32 degrees C, respectively. An average relative humidity was 58.2% during the experimental period. Three levels of dietary Na+ (0.20, 0.25, and 0.30%) and Cl- (0.30, 0.40, and 0.50%) were used in 3 x 3 factorial arrangement while maintaining a dietary electrolyte balance (DEB) of 250 mEq/kg. Higher weight gain (P < 0.002) and maximum water consumption (P < 0.05) were observed for birds fed diets containing 0.25 and 0.30% Na+, respectively. Litter moisture was significantly higher (P < 0.05) for birds fed diets containing 0.25% Na+ and 0.40 and 0.50% Cl-. High dietary Na+ (0.30%) tended to increase breast yield (P < 0.003) and decreased abdominal fat (P < 0.001). There was no effect of Na+ on blood pH or serum HCO3-. Diets containing 0.40% Cl- increased the dressing percentage (P < 0.001) and leg yield (P < 0.001) and decreased serum HCO3- (P < 0.001). There was no effect of dietary Cl- on blood pH, feed intake, weight gain, feed:gain, water intake, water:feed intake, or mortality. Significant dietary effect of Na+ x Cl- was noted only for litter moisture (P < 0.001), dressing percentage (P < 0.05), breast (P < 0.05) and leg (P < 0.001) yields, abdominal fat (P < 0.002), and serum HCO3- (P < 0.001). Birds fed diet containing 0.25% Na+ and 0.30% Cl- performed as well as those fed other diets when the cyclic temperature ranged from 32 to 39 degrees C.

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Gastrointestinal nematode (GIN) infections are a common constraint to small ruminant industry throughout the world, and among those, haemonchosis has its own significance. Control of GIN primarily relies on the use of anthelmintics, but this approach has become less reliable due to the development of resistance in GINs against commonly used anthelmintics and an increased consumer demand for environmentally friendly animal products. These issues have stimulated investigations to find alternative sustainable control strategies, which are less reliant on anthelmintic input. One of such strategies is breeding of small ruminants for their resistance to the GINs. The susceptibility and resistance of animals to GIN infections varies within and between breeds. Various parasitological, biochemical and immunological parameters are employed to evaluate natural resistance status of animals both in natural pasture and artificial infections. The immune mechanisms responsible for resistance are not completely understood, but it has a significant effect in inherited resistance. Relatively resistant or tolerant animals show better local and generalised immune response as compared to susceptible. Immune response against GINs is influenced by many physiological factors. Determination of specific genes linked with host resistance will provide a valuable approach to find out the molecular mechanism of host resistance to GINs. Resistance has been reported to reduce pasture contamination, which in turn reduces re-infection and thus the requirement of the frequent anthelmintic treatments. The efficiency of control can be increased through objective and accurate identification of genetically tolerant individuals by natural and artificial infections with GINs. Complete resistance is the ultimate solution, but this has generally been ignored as a commercial reality. This paper reviews the published reports on natural resistance in small ruminants and discusses the prospects of developing small ruminants, which could be resistant to GINs.