Impact of Replacing Different Levels of Potato Waste Silage with Barley on Growth Performance, Digestibility, Rumen and Blood Parameters of Fattening Lambs

The use of agricultural by-products instead of grain seeds in livestock diets has been an important issue for scientific study. One of these products is potato waste that, if properly processed by methods such as ensiling, can replace cereal seeds such as barley in the diet, due to the proper nutritional value of this product, improving animal growth performance, reducing feed costsand prevent food from being wasting. Therefore, the purpose of this study was to investigate the effect of replacing different levels of potato waste silage with barley on growth performance, digestibility, and rumen and blood parameters of fattening lambs.

In this study, 30 Zell and Afshar mixed male lambs with a mean weight of 26±2 kg and mean age of 5.5±0.4 months were used in a completely randomized design (CRD) with 5 treatments and 6 replications for 90 days. The experimental treatments included the control treatment (without potato waste silage) and the treatments containing 25, 50, 75 and 100 potato waste silage replacement of barley seeds (based on dry matter).

The results of performance traits showed that there was a significant difference in fattening weight, daily weight gain, dry matter intake and feed conversion ratio between experimental treatments (p<0.05). The highest and lowest final weight, daily weight gain and dry matter intake were observed in the treatment containing 50% of potato waste silage and the control treatment, respectively. The results of the apparent digestibility of nutrients of experimental diets showed that there was a significant difference in the apparent digestibility of raw protein and neutral detergent fiber (NDF) between experimental treatments (p<0.05). The highest and lowest apparent digestibility of crude protein (CP) was observed in the treatment containing 50% of potato waste silage and the control treatment, respectively. The results of some blood serum parameters showed that there was a significant difference in the concentration of glucose, triglyceride, Low density Lipoprotein (LDL) and blood urea nitrogen (BUN) between the experimental treatments (p<0.05). The results of rumen fermentation parameters showed that there was a significant difference in the population of lactic acid bacteria, coliforms, protozoa, rumen liquid ammonia nitrogen, total volatile fatty acids (VFAs), acetic acid, propionic acid, butyric acid, valeric acid and isovaleric acid between experimental treatments (p<0.05). The highest population of lactic acid bacteria 100%, the lowest coli form population, the highest population of protozoa and the highest concentration of VFAs were observed in the treatment containing 100%, 70%, 100% and 50% of potato waste silage, respectively.

The overall results of the present study showed that growth performance, the appearance of crude protein digestion, the total concentration of rumen fluid fatty acids and the population of bacteria and protozoa improved by consuming 50 % of potato waste silage