Browsing by Author "Tayengwa, Tawanda"

Now showing 1 - 3 of 3
  • Thumbnail Image
    Item
    Beef production and biopreservative effects of dietary citrus and winery by-products
    (Stellenbosch : Stellenbosch University, 2020-04) Tayengwa, Tawanda; Mapiye, Cletos; Dugan, Michael E. R.; Mutsvangwa, Timothy; Stellenbosch University. Faculty of AgriSciences. Dept. of Animal Sciences.
    ENGLISH ABSTRACT: The overall objective of the current study was to compare citrus pulp and grape pomace as dietary supplements and biopreservative for beef production and quality. Angus steers were fed 150 g/kg of dried citrus pulp (DCP) or grape pomace (DGP) as alternative fiber sources to wheat bran (control). Twenty-four steers (7 months old) were assigned to three dietary treatments (8 steers/ treatment) in a completely randomized design. Steer was the experimental unit. Steers were adapted for 21 d before 7 d of collecting feed, refusals, faecal and urine samples for determination of nutrient digestibility and utilisation. The digestibility trial was followed by a growth performance trial, which lasted 90d. During this period, dry matter intake (DMI), average daily gain (ADG) and feed efficiency data were collected. Post-feeding, steers were slaughtered and the left longissimus thoracis lumborum (LTL) from each carcass was sampled for physico-chemical meat quality attributes, shelf-life, major pro-oxidant fatty and volatile compound analyses, while the right LTL was sampled for the evaluation of eating quality attributes. Overall, steers fed the DGP diet had the greatest intake of dry matter (DM), organic matter (OM), crude protein (CP), ash free neutral detergent fiber (aNDFom), ether extract and starch followed by steers fed the DCP and control diets (P ≤ 0.05). Apparent digestibilities of DM, OM and aNDFom were greater (P ≤ 0.05) for the DCP diet compared to the DGP and control diets. Feeding the DCP and DGP diets increased (P ≤ 0.05) ruminal concentrations of total volatile fatty acids, acetate, isovalerate, acetate to propionate ratio, and reduced propionate concentrations compared to the control diet. The steers fed the control diet had the greatest urinary excretions of allantoin, uric acid and total purine derivatives followed by those fed the DCP and DGP diets (P ≤ 0.05). The nitrogen (N) intake, faecal nitrogen, N retention and N efficiency utilization were DGP > DCP > control diets (P ≤ 0.05). Feeding the DGP and DCP diets resulted in greater (P ≤ 0.05) ADG and final weight compared to the control diet. Steers fed the DGP diet had greater (P ≤ 0.05) DMI, warm and cold carcass weights than those fed the DCP and control diets. Shear force and income over feed costs were greatest for the DGP diet followed by the DCP and control diets (P ≤ 0.05). The DCP diet resulted in the greatest concentration of α-tocopherol in beef muscle tissues, followed by DGP and control diet (P ≤ 0.05). The beef antioxidant activity was DGP > DCP > control (P ≤ 0.05). During retail display DGP- or DCP-fed beef had greater L* (P ≤ 0.05) and fewer (P ≤ 0.05) coliforms than control diet fed beef. Beef TBARS and carbonyl contents were DGP < DCP < control (P ≤ 0.05). Overall, antioxidant activity decreased (P ≤ 0.05) while bacterial loads, TBARS and carbonyl contents increased (P ≤ 0.05) during retail display regardless of the diet. Feeding the DGP or DCP diets increased (P ≤ 0.05) the proportions of 18:2 n-6, 18:3 n-3 and total polyunsaturated fatty acid (FA) in LTL muscle. Beef from steers fed the control diet had greater (P ≤ 0.05) concentrations of alcohol, ketones and aldehydes, and lower (P ≤ 0.05) concentrations of sulphur containing compounds compared to the DCP- and DGP-fed beef (P ≤ 0.05). Feeding the DGP and DCP diets produced about 10% less tender (P ≤ 0.05) beef than the control diet. Overall, DGP improved nutrient intake, retention and efficiency of N utilization, growth performance, carcass attributes, beef shelf life, increase proportions of the main pro-oxidant fatty acids, and reduced aldehydes, ketones and alcohols associated with oxidation without compromising beef physicochemical and sensory quality. The current finding suggests that DGP may be a better fiber substitute and natural preservative in beef finishing diets than DCP.
  • Thumbnail Image
    Item
    Citrus and winery wastes : promising dietary supplements for sustainable ruminant animal nutrition, health, production, and meat quality
    (MDPI, 2018-10-16) Tayengwa, Tawanda; Mapiye, Cletos
    Citrus and grapes are the most widely grown fruits globally, with one-third of total production used for juice and wine making. The juice and winemaking processes generate large quantities of solid organic wastes including citrus pulp and grape pomace. These fruit wastes pose serious economic, environmental, and social challenges, especially in low-to-middle-income countries due to financial, technological, and infrastructural limitations. They are, however, rich in valuable compounds which can be utilized in the ruminant livestock industry as novel, economical, and natural sources of cellulose, polyunsaturated fatty acids, and phytochemicals, which have nutritional, anthelmintic, antioxidant, and antimicrobial properties. Despite citrus and grape fruit wastes having such potential, they remain underexploited by the livestock industry in low-to-middle-income countries owing to lack of finance, skills, technology, and infrastructure. Inclusion of these fruit wastes in ruminant diets could combine the desirable effects of enhancing animal nutrition, health, welfare, production, and meat quality attributes with the prevention of challenges associated with their disposal into the environment. The current review explores the valorization potential of citrus and winery wastes as dietary supplements to sustainably enhance ruminant animal nutrition, health, welfare, production, and meat quality.
  • Thumbnail Image
    Item
    Polyunsaturated fatty acid, volatile and sensory profiles of beef from steers fed citrus pulp or grape pomace
    (Elsevier, 2020-11-28) Tayengwa, Tawanda; Chikwanha, Obert C.; Neethling, Jeannine; Dugan, Michael E. R.; Mutsvangwa, Timothy; Mapiye, Cletos
    The present study compared the effects of feeding dried grape pomace (DGP) or citrus pulp (DCP) at 150 g/kg dry matter compared to a control diet on major polyunsaturated fatty acids (PUFA), volatile and sensory profiles of beef. Feeding DGP or DCP diets to Angus steers for 90 d increased the proportions of C18:2n-6, C20:4n-6, C18:3n-3, total conjugated linoleic acid (CLA), n-3 and n-6 PUFA in muscle. Control-fed beef had greater concentrations of C18:1n-9, total aldehydes, ketones, and alcohols compared to DCP and DGP. Feeding DGP and DCP diets produced less tender beef than control. Overall, finishing steers on diets containing DGP or DCP compared to control increased proportions of total CLA, n-3 and n-6 PUFA, and reduced concentrations of aldehydes, ketones, and alcohols, but did not affect beef sensory attributes except for a slight reduction in tenderness.