THE ROLE OF SOME ADDITIVES IN ENHANCING FEED EFFICIENCY AND HEALTH IN MONOGASTRIC ANIMALS

The global demand for food from animal agriculture is anticipated to nearly double by 2050. The growth in white meat (pork and poultry) production in developing countries between 1989 and 1999 has been remarkable - more than double the growth of red meat (cattle, sheep and goats). Increased production can be achieved by a combination of expansion in animal numbers and increased productivity. Higher productivity is a compound of higher offtake rates (shorter production cycles by, for example, faster fattening), and higher carcass weight or milk or egg yields. The projections show that the increase in livestock numbers will remain significant, but less so than in the past. Higher carcass weights will play a more important role in beef production, while higher offtake rates (shorter production cycles) will be more important in pig and poultry meat production. In order to increase health and feed efficiency in monogastric animals, four trials were carried out to evaluate the role of some additives used to increase health in post-weaning piglets and in poultry meat production. The aim of first study was to evaluate the effects of nucleotides administration to post-weaning piglets on ileal proinflammatory interleukin gene expression. Thirty-six weanling piglets (28 d of age, 7.85 ± 0.25 kg L.W.) were used in 28 days study. Piglets were allotted to 2 homogeneous groups (C, T) and fed the basal diet supplemented with oral nucleotides (UMP 88.05%, GMP 5.51%, AMP 3.82%, CMP 1.94% and IMP 0.68%; 0.8 g/piglet/day in 2.1 ml water solution) or saline. On day 14 both experimental groups were challenged with 1x109 CFU/g E. coli 0149:F4(K88). Growth performance and faecal score were evaluated weekly, while blood samples for immunological serum parameters, Fe and Vitamin B12 serum content were collected on days 0, 13, 18 and 26. Proinflammatory IL1a, IL1b, IL6, IL10, and TNF, TLR2 and TLR4 gene expression in ileal Peyer patches were evaluated at slaughtering after individual tissue sample collection by RT-PCR and β-actin as housekeeping gene. Growth performances were not affected by dietary treatment, while faecal score was ameliorated in T piglets after one week on trial (P< 0.05). Haptoglobin serum content was decreased in treated pigs (P<0.01). Dietary treatment did not affect serum Fe content, while vitamin B12 level was higher in nucleotide-fed animals (P< 0.05). At slaughtering IL6, IL10, TNF, TLR2 and TLR4 gene expression were decreased in nucleotide-fed pigs (P< 0.01). By these findings, dietary nucleotides supplementation in post-weaning piglets can positively affect gut health status, ameliorating inflammatory response and digestibility of nutrients in microbial stress conditions. Second study was carried out with the aim to investigate the antimicrobial potential of a polyphenol-rich olive extract in vitro and its effects on growth performance, caecum microbial population, slaughtering performance and meat quality. In vitro antimicrobial trials were performed on test cultures (E. coli ATCC 25922, L. monocytogenes ATCC 7644, S. Enteritidis ATCC 12592 and S. aureus ATCC 6833); the growth was assessed every 12 h for 48 h as optical density of broth cultures added with different concentrations of the product (0.1/0.5/1/5%) incubated at 20°C; an evident inhibition was observed with the increasing of the product concentration and a total inhibition was observed with the highest one. Considering these results, an in vivo trial was performed. A total of 720 female ROSS308 broiler chicks with day-old were allocated into 4 treatments with different dietary treatments (basal diet supplemented without (CTR) or with vitamin E (T1, 200 I.U. /kg for each dietary phase) or with Polyphenols olive extract (T2, 1g/kg and T3, 5 g/kg respectively in each dietary phase). Each group consisted of 9 pens with 20 birds per pen. Growth performances were determined at days 0, 10, 20 and 35. At day 35, two birds of each pen were chosen on average pen weight basis and slaughtered: from one was collected the cecum for microbial analyses and for the determination of the dressing and breast muscle percentages and the other one was collected for the measurements of pH, TBARS content and color at day 0 and after 9 days, mimicking the commercial preservation after slaughter. Supplementation with polyphenols olive extract showed only a tendency in Feed Conversion Ratio, in particular in the three phase of administration and in overall performance period (0-35 d) of animals (respectively P=0.09 and P=0.07) and T2 result lower compared to control group. No other evidence was observed in growth performances measured included carcass measures on dressing and breast muscle percentage. In addition, no differences were observed in cecum microbial population and gut health indexes. TBARS showed a statistical tendency (P=0.075), T1 resulted with lower oxidation if compared to all other groups (P<0.05); pH value and color of breast, skin and thigh, expressed with L*, a* and b*, did not explain any statistically difference. In conclusion in addition to promising in vitro data obtained, it would be interesting to evaluate the potential of the administration of this type of polyphenols in animals subjected to the stress of intensive livestock production, where more interesting results due to potential expressed with antimicrobial and antioxidant activity could be obtained. Third and fourth trials were carried out to evaluate different effects of a novel synthetic emulsifier. First step, the third trial, consist in two experiments conducted to evaluate the effects of a novel synthetic emulsifier product (AVI-MUL TOP) on the growth performance of chickens for fattening and weaned piglets. The emulsifier product consists of 50% vegetal bi-distillated oleic acid emulsified with 50% glyceryl polyethyleneglycol ricinoleate. In Exp. 1, four hundred and eighty 1-d-old female Cobb500 chickens for fattening were assigned to two treatments: 1) a control diet (CTR); and 2) the control diet + the emulsifier (AMT, 1 g/kg from day 0 to day 10, 0.75 g/kg from day 10 to day 20 and 0.5 g/kg from day 20 to day 34). AMT supplementation increased body weight on days 20 and 34 (P < 0.01). Dietary AMT increased the average daily gain (ADG) and average daily feed intake (ADFI) from day 10 to day 20, from day 20 to day 34 and from day 0 to 34 (P < 0.01). A reduced feed conversion ratio was observed in the AMT group from day 10 to day 20 (P < 0.01). In Exp. 2, ninety-six Stambo HBI × Dalland piglets were weaned at 24 days and assigned to 2 treatments (the basal diet without the product (CTR) or with 2 g/kg emulsifier from day 0 to day 14 and 1.5 g/kg from day 14 to day 42 (AMT)). There was an increase in the ADFI associated with AMT supplementation from day 14 to day 42 (P = 0.04). These results indicated that supplementation with the synthetic emulsifier may significantly improve the growth performance of chickens for fattening and numerically improve that of weaned piglets. Second step consist in to investigate the influence of a novel synthetic emulsifier product (AVI-MUL TOP) on growth performance, plasma lipid profile and hepatic expression of related genes in female and male broiler chicks. A total of 1200 ROSS308 broiler chicks with day-old were allocated into 4 treatments with a 2 × 2 factorial design comparing sex (female or male) and different dietary treatments (basal diet supplemented without (CTR) or with the emulsifier (AMT, 1 g/kg from d 0 to 12, 0.75 g/kg from d 12 to 22 and 0.5 g/kg from d 22 to 44, respectively)). Each group consisted of 15 pens, 20 birds per pen. Growth performance was determined at days 0, 12, 22 and 44 (37 for females). At day 44 (37 for females), one bird of each pen was chosen and slaughtered to collect blood and livers samples and determine the dressing and breast muscle percentages. Males had higher BW than female chicks on days 0 (P = 0.014), 12 (P < 0.01) and 22 (P < 0.01). Compared to females, male chicks had higher ADG and ADFI from day 0 to 12 and from day 12 to 22 (P < 0.01), and lower FCR from day 12 to 22 (P < 0.01). AMT supplementation increased the BW compared to the CTR group on days 12 (P = 0.02), and AMT chicks had higher ADG compared to the CTR birds from day 0 to 12 (P = 0.02). AMT male chicks had lower FCR compared to the CTR males from day 22 to 44 and day 0 to 44 (P = 0.047 and 0.02). However, there was no diet effect on growth performance of female chicks during the trial. AMT supplementation increased dressing percentage compared to the CTR group (P = 0.02). In addition, dietary AMT increased cholesterol, HDL and LDL contents compared to the CTR group (P < 0.01; P = 0.02; P < 0.01). In conclusion, supplementation of AMT may have beneficial effect on growth performance and plasma lipid profile of broiler chicks.