Effects of Soybean and Linseed Oils Calcium Salts and Starter Protein Content on Growth Performance, Immune Response, and Nitrogen Utilization Efficiency in Holstein Dairy Calves.

This study aimed to investigate the interaction of fatty acid (FA) source [calcium salt of soybean oil (n-6 FA) vs. calcium salt of linseed oil (n-3 FA) both 3% DM basis] with protein content (18% vs. 22% CP, based on DM) on growth performance, blood metabolites, immune function, skeletal growth indices, urinary purine derivatives (PD), and microbial protein synthesis (MPS) in young dairy calves. Forty 3-day-old calves (20 females and 20 males) with a starting body weight (BW) of 40.2 kg were assigned in a completely randomized block design in a 2 × 2 factorial arrangement of treatments. Experimental diets were: (1) n-6 FA with 18% CP (n-6-18CP), (2) n-6 FA with 22% CP (n-6-22CP), (3) n-3 FA with 18% CP (n-3-18CP), and (4) n-3 FA with 22% CP (n-3-22CP). Starter feed intake and average daily gain (ADG) were not influenced by experimental diets (p > 0.05). However, before weaning and the entire period, feed efficiency (FE) was greater in calves fed n-3 FA compared to n-6 FA (p < 0.05). Heart girth (weaning, p < 0.05) and hip height (weaning, p < 0.05 and final, p < 0.01) were highest among experimental treatments in calves who received n-3-22CP diets. The greatest blood glucose (p < 0.05) and insulin (p < 0.01) concentrations in the pre-weaning period and the lowest serum concentration of tumor necrosis factor (before weaning, p < 0.05) were observed in calves fed the n-3-22CP diet. However, the greatest blood urea N (before weaning, p < 0.05; after weaning, p < 0.05) and urinary N excretion (p < 0.05) were found in calves fed n-6-22CP diets compared to other experimental arrangements. In conclusion, offering calves with Ca-salt of n-3 FA along with 22% CP content may be related to improved nitrogen efficiency and immune function.

Effect of threonine and potassium carbonate on broiler chicken performance, immunity, carcass traits, and small intestine morphology.

This study aimed to investigate the interactive effect of dietary threonine (i.e., 100, 110, and 120%) and low and high dietary potassium (i.e., 0.85 and 0.94% of diet) on the performance, immune response, blood metabolites, carcass traits, and jejunum morphology of broiler chickens in Iran. In a completely randomized design, 300 1-day-old broiler chicks (Ross 308) were assigned to one of six dietary treatments with a 3 × 2 factorial arrangement. Broiler chicken growth performance, blood metabolite concentration, jejunum morphology, and antibody titter against Newcastle disease and influenza viruses were not affected by dietary treatments (P > 0.05). High level of dietary potassium led to lower toe web thickness index at 4 h post injection while compared to control group, threonine supplementation significantly decreased toe web thickness of broiler chickens at 24 and 48 h post injection (P < 0.05). Dietary treatments had no significant effects on carcass, abdominal fat, and breast and thigh percentages while higher dietary potassium increased serum glucose concentration (P < 0.05). Broilers fed diet supplemented with 20% supplemented threonine and higher potassium level had lower breast meat fat percentage while those fed diet supplemented with 20% threonine and low potassium had higher thigh meat protein percentage (P < 0.05). It can be concluded that although threonine supplementation improved toe web thickness index as cell-mediated immune response and lowered breast meat fat percentage in broiler chickens, there was no interaction between potassium with threonine in broiler chicken nutrition.