Effect of microwave-treated poultry byproduct meal on growth performance, rumen Parameters, microbial protein, and nitrogen retention in Dalagh fattening lambs

The use of conventional feed sources in livestock diets has caused that in addition to increasing demand, prices and imports also increase. On the other hand, the use of feed industry residues and their processing can provide reliable sources of nutrients in livestock diets. Therefore, this experiment was performed to investigate the processing of microwave electromagnetic waves on poultry byproduct meal on growth performance, rumen parameters, microbial protein production and nitrogen retention in fattening lambs.

Fifteen mixed male lambs with an average weight of 29.3±2.7 were used in a completely randomized design with 3 feed treatments and 5 replications. Treatments include: 1- Soybean meal, 2- poultry byproduct meal, 3- Microwave poultry byproduct meal. The experiment consisted of 14 days of adaptation and 70 days of fattening. Weighing was done every 14 days. Feeding was done at 7:00 and 19:00. Daily feed intake, initial weight, final weight were measured and recorded. Measurement of microbial protein produced in the rumen was calculated by estimating purine derivatives excreted through urine collection. On the last day of the experiment, three hours after the morning feeding, ruminal fluids were taken using a stomach tube and a vacuum pump. Then it was used to calculate the population of bacteria and protozoa, to determine the concentration of volatile fatty acids using standard internal solution and gas chromatography, to determine the concentration of ammonia nitrogen and the pH of ruminal fluid.

The use of microwave poultry byproduct meal in the diet instead of soybean meal in dry matter intake was not significantly different. Daily weight gain and total weight gain in microwave poultry byproduct meal treatment was against treatment of process without 324.3 and 22.7 kg versus 0.277 and 19.4 kg, respectively, with significant difference and improved traits (P <0.05). Also, feed conversion rate and feed efficiency between treatments 3 and 2 were 7.446, 0.135 and 8.455, 0.119, respectively, which showed a significant difference at the level of P <0.07 and P <0.08. The highest bacterial population (28.8*109 ml) was observed in soybean meal treatment and was significantly different from other treatments (P <0.05) but no significant difference was observed between treatments in protozoan population. Rumen pH between treatments 1 and 3 were 6.73 and 5.79 respectively (P <0.05). There was no significant difference in ammonia nitrogen concentration in ruminal fluid between treatments. The percentage of acetate, propionate and the ratio of acetate to propionate in treatment of processed poultry byproduct meal are 65.8, 18.8 and 3.5, respectively, which are the lowest, highest and lowest traits in comparison with other treatments, respectively (P<0.05). There was no significant difference in microbial protein production between treatments. The apparent nitrogen retention in the microwave treatment was 27.129 g / day which was not significantly different from other treatments and its lowest amount (24.861 g / day) was for soybean meal treatment and its highest amount was for conventional treatments with poultry byproduct meal was 32.148 g / day (P> 0.06).

This study showed that the effect of poultry byproduct meal processing by microwave method on growth performance traits was better than poultry byproduct meal without processing. Microwave replacement of conventional poultry byproduct meal with soybean meal did not differ significantly in growth performance traits. Also, replacing microwave and microwave poultry byproduct meal with soybean meal in the diet of fattening lambs without creating unfavorable conditions on rumen parameters and apparent nitrogen retention can replace soybean meal with up to 10% dry matter, reduce soybean meal demand and imports.