Research On Animal Production

Extended Abstract
Background: Every day, large amounts of rumen contents are produced as waste in slaughterhouses and are left unused in the environment, which causes environmental problems. Compared to other processing methods, bioconversion is a new and desirable method for managing agricultural waste and residues. As a rich source of enzymes, ruminal liquid can be used in the bioconversion of agricultural wastes. About 35% of all potatoes are thrown away as waste during different stages. Potato waste is a suitable raw material that can be used as a valuable protein by-product during the simple fermentation process by using rumen liquid obtained from slaughterhouse waste and adding various non-protein nitrogen (NPN) sources. For this purpose, the effect of using processed potato waste with rumen contents was evaluated in the diet of fattening lambs.
Methods: The slow-release NPN source used in this experiment, with the brand name Nitrosa, contained a 40% nitrogen equivalent to 250% of crude protein. The best level of NPN for processing potato waste using the potential of rumen liquid microorganisms based on the results of the crude protein content of the solid part produced during incubation for use in the farm sector was determined at 3 g of nitrogen from a Nitrosa source. A constant ratio of rumen liquid to waste potatoes (2:1) was chosen for the ratio of 400 ml of rumen liquid + 200 g of damaged potatoes. The solid part of the fermented product of the semi-industrial production of potato waste processing with rumen liquid and urea was included in the diet of 24 heads of 5-month-old Romanov-Moghani crossbreed lambs with four diets and six replications (lambs) at three replacement levels of 2.5, 5, and 7.5%of the basic diet of the 78-day fattening period of the lambs. The average weight of the lambs in the groups was 31.1 kg at the beginning of the period. The experimental groups were 1) basic diet (without processed potato waste), 2) basic diet with 2.5% processed potato waste (the dried solid phase), 3) basic diet with 5% processed potato waste (the dried solid phase), and 4) basic diet with 7.5% processed potato waste (the dried solid phase). To determine the concentration of blood metabolites in all lambs, blood was drawn from the jugular vein 3 hours after consuming feed on the 60^th day of the fattening period. Then, the blood parameters, including glucose, blood urea nitrogen, cholesterol, triglyceride, total protein, albumin, high-density lipoprotein, alanine aminotransferase, aspartate aminotransferase, and BHBA, were determined with Pars Azmoun kits using a spectrophotometer. Total antioxidant capacity, glutathione peroxidase, and superoxide dismutase were measured using RANDOX kits. The concentration of malondialdehyde was measured using the reaction of thiobarbituric acid with malondialdehyde, with the Ransod RANDOX kit by an autoanalyzer.
To measure the carcass characteristics, the lambs were weighed at the end of the fattening period. The measured traits included hot and cold carcass weights, tail weight, heart, liver, kidney, and lung of the slaughtered lambs. Carcass yield was calculated by dividing the carcass weight by the final live weight. All the carcasses were separated from the area between the last back vertebra and the first tail vertebra between the slip joint, and the carcass without the tail was weighed by a digital scale to obtain the carcass weight without the tail. The tails of all the carcasses were separated from the part between the last vertebra of the back and the first vertebra of the tail between the slip joint and weighed with a digital scale. The tail percentage was calculated by dividing the tail weight by the carcass weight.
Results: There was no significant difference between the groups in the dry matter intake, FCR, daily weight gain, and final weight of lambs during the fattening period. The average daily weight gain levels of the lambs of the 5% level were 228.6, 218.0, and 231.0 g for the second, third, and whole periods, respectively. The results showed that the lambs of this level gained the lightest body weight with a final weight of 49.18 kg. The lambs of the 2.5% level showed the highest amount in line with the data of the FCR in the whole period with an average daily weight gain of 241.6 g. Therefore, the final weight of Moghani lambs of this level at the time of slaughter was 49.99 kg, that is, the heaviest lambs for this group. The results of blood analysis showed no significant differences between the experimental groups, and blood factors were not influenced by different substitution levels of the experimental substance. The antioxidant activity index and the concentration of malondialdehyde in the blood serum of lambs were not affected by the diets. From the results and data analysis, no significant differences were observed in the weight factors of the hot carcass, heart, liver, kidney, lung, back fat thickness, tail, and finally cold carcass.
Conclusion: The results show that it is possible to improve the nutritional value of potato waste by using rumen contents to process potato waste while supplementing it with urea and use the produced experimental material in feeding ruminants. In this research, the semi-industrial production of the experimental material of potato waste processed with rumen contents and its replacement at three levels of 2.5, 5, and 7.5% in the diet of fattening lambs showed no significant differences between the groups in dry matter consumption, FCR, daily weight gain, and final weight. Moreover, no significant differences were observed between the experimental groups in carcass characteristics and meat yield. The experimental material of potato waste processed with rumen contents, without significant differences and yield reduction, could meet the requirements of fattening lambs.