Effect of Potato Vine and Leaf Mixed Silage Compared to Whole Corn Crops on Growth Performance, Apparent Digestibility, and Serum Biochemical Characteristics of Fattening Angus Bull

SIMPLE SUMMARY: Potato (Solanum tuberosum L.) is a worldwide-used food and is a perennial plant in the nightshade family Solanaceae. Potato vine and leaf mixed silage (PVS) is detoxicated after ensiling and can be used as high-quality roughage for ruminant animals. Because the PVS’s inadequate nutrient content cannot meet the requirement of ensiling, especially due to its lack of the water-soluble carbohydrates, the only method for ensiling consists of mixing with different feed ingredients. In this trial, the blood urea nitrogen and crude protein digestibility of the Angus bull were significantly higher when fed with PVS. The result revealed a high content of crude protein, crude protein apparent digestibility, and ash content in PVS compared with CS in the feeding trial. PVS significantly decreased Angus bulls’ average daily gain and feed conversion rate and increased high-density lipoprotein cholesterol (HDL-C) and low-density lipoprotein cholesterol (LDL-C). Because potato vine and leaf as a by-product of potato production can achieve the same economic production targets for beef cattle and still meet the requirements of sustainable development, the aim of this trial was therefore to investigate the possibilities of PVS in ruminant silage substitution and hopefully to give some guidance on conventional silage substitution. ABSTRACT: This study aims to explore the different growth performances of the Angus bull on potato vine and leaf mixed silage in the early fattening period and to provide a reference animal production trial. Thirty-six 13-month-old Angus bulls were divided into three groups with 403.22 ± 38.97 kg initial body weight and fed with three different silage diets: (1) control: whole-plant corn silage as control (CS); (2) treatment 1: 50% whole-plant corn +50% potato vine and leaf silage (PVS1); and (3) treatment 2: 75% potato vine and leaf +15% rice straw +10% cornmeal silage (PVS2). After the 14 days pre-feeding, the formal experiment was carried out for 89 days. The result showed that the ash content of the potato vine and leaf mixed silage (PVS) in the treatment groups was higher than that in control group, and the ash content of PVS1 and PVS2 even reached 10.42% and 18.48% (DM%), respectively, which was much higher than that of the CS group at 4.94%. The crude protein content in silage also increased with the additional amount of potato vine and leaf. The apparent crude protein digestibility of the PVS groups was also significantly higher than that of the CS group (p < 0.05). In terms of serum biochemical indexes, blood urea nitrogen (BUN) in the experimental groups was significantly higher than in the control group (p < 0.05). Compared with PVS2, cholesterol (CHO) was significantly lower in the CS and PVS1 groups (p < 0.05). Moreover, the high-density lipoprotein cholesterol (HDL-C) and low-density lipoprotein cholesterol (LDL-C) of PVS2 were significantly higher than those of the CS and PVS1 group (p < 0.05), and daily gain (ADG) as a key production index had a significantly negative correlation with the CHO (r = −0.38, p < 0.05) and HDL-C (r = −0.40, p < 0.05) of cattle. In conclusion, PVS had higher crude protein content and ash but less starch than whole-corn silage. The PVS could replace whole-plant corn silage at the same dry matter status and did not affect the weight gain in this trial.