Growth performance, blood metabolic responses, and carcass characteristics of grower and finisher South African Windsnyer-type indigenous and Large White × Landrace crossbred pigs fed diets containing ensiled corncobs1

A study was taken to evaluate growth performance, carcass characteristics, and blood metabolite concentrations when ensiled corncobs were included in indigenous and commercial pig diets. Fifty Large White x Landrace (LWxLR) crossbred pigs and 30 South African Windsnyer-type indigenous pigs (SAWIP) were evaluated. They were fed a control (CON), a low inclusion of ensiled corncob (LMC), and a high inclusion of ensiled corncob (HMC) diet in a completely randomized block design. The LWxLR crosses had greater (P < 0.05) final weight, ADFI, DMI, ADG, and G:F ratios than the SAWIP at both the grower and finisher stages. The SAWIP consumed more feed per metabolic BW (BW^sup 0.75^) than LWxLR crosses at the grower stage while LWxLR crosses consumed more than SAWIP at the finisher stage (P < 0.05). The finishers' G:F ratio was greater (P < 0.05) in the CON than in the HMC diet. The LWxLR growers and finishers had greater (P < 0.05) warm carcass weight (WCW), cold carcass weight (CCW), carcass length, drip loss, pH at 24 h, eye muscle area, and lean percent than those of SAWIP growers and finishers. The LWxLR finishers on the CON diet had greater (P < 0.05) WCW and CCW than those on the HMC and LMC diets. There were diet x breed interactions for dorsal fat thickness at first rib (DFT1), dorsal fat thickness at last lumbar vertebra (DFT3), backfat thickness (BFT), and hindquarter weight proportion (HQWP) in the growers. The LWxLR growers and finishers had greater values (P < 0.05) of hindquarter length, hindquarter circumference, HQWP, and shoulder weight proportion than the SAWIP growers and finishers, respectively. The SAWIP growers and finishers had greater values (P < 0.05) of DFT1, dorsal fat thickness at last rib, DFT3, and BFT than the LWxLR growers and finishers, respectively. There were breed x diet interactions (P < 0.05) for alanine aminotransferase and amylase (AMYL). The LWxLR crosses had greater (P < 0.05) values of creatinine, phosphorus, alkaline phosphatase, cholesterol, and AMYL than the SAWIP. The breed of pig influenced most of the growth performance and carcass parameters more than the diet did. There was no clear link between the blood metabolite levels and the diets. Since the inclusion of ensiled corncobs in diets did not affect negatively the selected important commercial pork cuts in South Africa, this could imply that they have a greater role as a pig feed resource.