Response in growth performance, carcass traits, fatty acid profiles and health indices of pork from windsnyer pigs supplemented with amarula oil cake.

Abstract

To conserve the slow-growing Windsnyer pigs, it is crucial to explore their efficiency in utilising locally available ingredients such as Amarula oil cake (AOC). The use of Amarula oil cake in pig diets can ease the pressure of relying on conventional feed sources and broaden the feed resource base for pigs. The broad objective of the study was to assess the relationship between feeding increasing levels of Amarula oil cake on the growth performance of Windsnyer pigs and selected pork quality traits. Twentyfive clinically healthy intact growing boars with an initial body weight of 19.9 ± 8.74 kg were used in the study which lasted for six weeks excluding the adaptation period of one week. Pigs were assigned to five experimental diets in a completely randomised design and diets were formulated to contain 0, 50, 100, 150, and 200 g/kg DM of AOC. The average daily feed intake (ADFI), average daily gain (ADG), feed conversion ratio (FCR), scaled average daily feed intake (SADFI), scaled average daily gain (SADG), and body weight (BW) were calculated weekly. The diet affected ADFI, ADG, FCR, and SADG (P < 0.05). The scaled average daily feed intake was not affected by the diet (P > 0.05). There was a significant interaction between AOC inclusion and weeks of feeding on ADFI, ADG, and FCR (P < 0.05). A positive quadratic relationship between ADFI and increasing levels of AOC was observed (P < 0.05). Average daily gain, FCR, and SADG decreased linearly with increasing AOC levels (P < 0.05). Using the broken stick analyses, the maximum inclusion level of AOC was obtained at 102.17 g/kg DM with an optimum ADFI of 1.25 kg/day. Amarula oil cake can be incorporated in Windsnyer pig diets up to 100 g/kg DM without constraining growth performance of Windsnyer pigs. v The specific objective for experiment two was to determine the relationship between incremental levels of AOC, carcass characteristics, primal pork cuts, and visceral organ weights of South African Windsnyer pigs. There was a negative linear relationship between increasing AOC levels, carcass length, warm carcass weight, and cold carcass weight (P < 0.05). Stomach weight, backfat thickness, drip loss, and the hepatosomatic index increased linearly with increasing AOC levels (P < 0.05). The kidneys, small intestines, and large intestines weight of Windsnyer pigs had a quadratic response to AOC inclusion level (P < 0.05). The heart, lungs, and spleen were not related to increasing levels of Amarula oil cake inclusion (P > 0.05). Incremental AOC diets impaired carcass characteristics and the selected visceral organs of pigs. Windsnyer pigs can, therefore, be fed Amarula oil cake up to 100 g/kg dry matter. The specific objective for experiment three was to assess the changes in nutritionally related metabolites and liver enzymes of Windsnyer pigs fed on increasing levels of AOC based diets. After subjecting the pigs to six weeks of feeding on the experimental diets, blood samples were collected. Serum was analysed for total protein (TP), albumin, globulin (G) iron, Uric acid (UA), albumin: globulin ratio (A: G), alkaline phosphatases (ALP), aspartate aminotransferase (AST), aminotransferase (ALT). The albumin concentration of pigs linearly decreased with incremental levels of AOC (P < 0.05). The concentration of TP and G decreased quadratically with incremental levels of AOC (P < 0.05). On the other hand, ALP increased quadratically with increasing levels of AOC (P < 0.05). The other blood metabolites and liver enzymes were not related to the inclusion level of AOC (P > 0.05). The specific objective for experiment four was to determine the relation between fatty acid composition and health lipid indices of pork from Windsnyer pigs supplemented with different AOC levels. Increasing AOC inclusion levels, linearly increased C12:0, C14:1n9c, C18:1n9t and C18:3n6 of pork from Windsnyer pigs (P < 0.05). Increasing AOC levels linearly decreased SFA, PUFA/SFA ratio, C18:1n11c and C20:3n3 of pork from Windsnyer pigs (P < 0.05). There was a quadratic decrease in n-3 fatty acids, n- 6/n-3 ratio, nutritive value, C22:0, C18:1n9c, C18:3n3, C18:2c911t, C20:4n6 and C22:5n3 of pork (P < 0.05). The total MUFA, PUFA, n-6 fatty acids, AI and TI were not related to AOC inclusion (P > 0.05). Due to the quadratic relation of n-3 PUFA, n-6/n- 3 ratio of FA and nutritional value of pork, it is recommended that AOC based diets be fed up to 150 g/kg DM. Low levels of AOC of up to 100 g/kg DM improved growth performance, nutritionally related metabolites, carcass traits of pigs. High inclusion levels of AOC improved fatty composition of pork from Windsnyer pigs. Key words: Body weight gain; carcass length: dietary fibres; feed intake; hepatosomatic index; organ weight; total protein; polyunsaturated fatty acids; saturated fatty acids.