Whole cottonseed in high concentrate diets for finishing Nellore beef cattle

Author(s)

Vinicius Nunes de Gouvêa

• Document type: Doctoral Thesis
• Press: Pirassununga.
• Institution: Universidade de São Paulo (USP). Faculdade de Medicina Veterinária e Zootecnia (FMVZ/SBD)
• Defense date: 2015-12-14

Examining board members

Alexandre Vaz Pires; Paulo Roberto Leme; Paulo Henrique Mazza Rodrigues; Flavio Augusto Portela Santos; Saulo da Luz e Silva

• Advisor: Alexandre Vaz Pires

Abstract

Three trials were conducted to evaluate the effects of the inclusion of levels of whole cottonseed (WC) or soybean oil (SO) in diets for Nellore feedlot cattle. In the experiment I six rumen-cannulated Nellore steers (407 ± 24 kg BW) were used in a 6 x 6 Latin square design experiment. Were evaluated 5 levels of inclusion of WC (0, 8, 16, 24 and 32% DM basis) in diets containing 87% concentrate (treatments WC0, WC 8, WC16, WC24 and WC32 respectively). Also, it was evaluated a diet containing the same amount of total fat content of WC32 but with no WC and using soybean oil (SO treatment). Increasing WC levels linearly decreased DM and OM intake (P < 0.01). CP and NDF intakes were not affected by the treatments. Total fat digestibility linearly increased due the WC increase in the diets (P < 0.001). Total DM (P = 0.019) and OM (P = 0.020) digestibilities linearly decreased with increasing levels of WC. SO inclusion did not affect DM (P = 0.462) and OM (P = 0,469) digestibilities compared with CA0 and there was no effect of fat source over DM (P = 0.124) and OM (P = 0.110) digestibilities. Rumination time linearly increased due the WC inclusion (P = 0,002). Increasing WC levels quadratically increased ruminal pH (P < 0.05) but no effect was observed with the SO addiction in the diet (P = 0.329) compared with CA0. Total VFA was linearly decreased with increasing levels of WC (P < 0.001). Increasing levels of WC linearly decreased the microbial protein synthesis (P = 0.011). In the experiment II a total of 280 Nellore bulls (initial BW = 349 ± 33 kg) were allotted in 40 pens. The statistical design was randomized incomplete blocks. The maximum final BW was obtained with 7.6% of inclusion of WC. Increasing levels of WC decreased DMI (P < 0.001). Adding SO also decreased DMI (P < 0.05) compared with WC0. Increasing the inclusion rate of WC quadractically increased the ADG, G:F, HCW, dressing percent, LM area and 12-rib fat (P < 0.05). The maximum ADG were obtained with 8% of inclusion of WC. On the other hand, the maximum G:F was obtained with 14.5% of WC. Compared with WC0, the SO inclusion did not affect carcass characteristics (P > 0.05). The inclusion of WC quadractically affect meat composition (P < 0.05). Compared with CA32, the inclusion of SO in the diet did not affect the meat composition. Increasing WC in the diets quadratically decrease (P = 0.035) lipid oxidation. No effects were observed in the sensorial evaluation flavor, taste and overall acceptability by the costumers (P > 0.05). Training sensory panelists also did not find differences between the treatments for flavor and taste. Increasing WC linearly decreased the tenderness (P = 0.045). Compared with CA32, the inclusion of SO increased meat tenderness (P = 0.031). In the experiment III was evaluated the ruminal fermentation kinetics of corn and cottonseed through the in vitro gas production technique. Five bottles for each energy source (corn and cottonseed), plus five additional bottles containing buffered medium and rumen fluid inoculum only (blanks) were used. The volume of gas produced was recorded at 0, 2, 4, 6, 8, 10, 12, 15, 19, 24, 30, 36, 48, 72 e 96 h of incubation using the pressure reading technique. Gas values were corrected for blank incubations. The corn had greater gas production than cottonseed (P < 0.001). Lag time was not different between the two energy sources (P = 0.646). Cottonseed had higher FDR than corn (P = 0.001) and shorter time to half asymptote (P < 0.001). Corn had higher potential of degradation compared with cottonseed observed by the higher gas production. Moreover, even with lower potential of degradation, the cottonseed fibrous fraction had a high degradability compared to corn (AU)

• FAPESP's process: 12/14289-0 - Effects of whole cottonseed in finishing Nelore feedlot cattle diets on performance, carcass characteristics, ruminal metabolism and nutrients digestibility.
• Grantee: Vinícius Nunes de Gouvêa
• Support Opportunities: Scholarships in Brazil - Doctorate