Browsing by Author "Pieterse, Elsje"

Now showing 1 - 4 of 4
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    Combined effect of dietary protein, ractopamine, and immunocastration on boar taint compounds, and using testicle parameters as an indicator of success
    (MDPI, 2020-11-14) Needham, Tersia; Gous, Rob M.; Lambrechts, Helet; Pieterse, Elsje; Hoffman, Louwrens C.
    This study investigates the combined effect of immunocastration, dietary protein level (low, medium or high) and ractopamine hydrochloride supplementation (0 or 10 mg/kg) on the adipose concentrations of androstenone, skatole and indole in pigs, and explores whether body mass, carcass fatness or testicular parameters may be indicators of boar taint in these carcasses. Immunocastration was successful in decreasing testicle functioning, and adipose androstenone and skatole concentrations, in all individuals. Immunocastration decreased testicle weight and length, seminiferous tubule circumference and epithelium thickness. Testicle tissue from immunocastrates was also paler, and less red in color, in comparison to non-castrated controls. Dietary protein level and ractopamine hydrochloride supplementation had no influence on the adipose concentration of androstenone, skatole and indole. Testicle size and color were moderate to strong indicators of androstenone and skatole concentrations in the carcasses, and thus vaccination success. Immunocastration together with the adjustment of dietary protein and ractopamine hydrochloride supplementation, is successful in preventing boar taint while maintaining growth performance.
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    Effects of increased slaughter weight of pigs on pork production
    (Stellenbosch : Stellenbosch University, 2006-04) Pieterse, Elsje; Hoffman, Louwrens C.; Siebrits, F. K.; Stellenbosch University. Faculty of AgriSciences. Dept. of Animal Sciences.
    ENGLISH ABSTRACT: The South African pork industry is characterised by low slaughter weights when compared to the rest of the world. This inevitably leads to a smaller number of kilograms produced per unit fixed cost and subsequently the efficiency of production is reduced. A study was conducted with 189 pigs representing three sex types (boar, gilt and castrate) and five commercial genotypes. Pigs entered into the trial at an age of 10 weeks and an average live weight of 27.5±2.5kg. Treatments were according to slaughter weight ranging between 62 and 146kg. Production and carcass characteristics, meat quality and processing characteristics and sensory attributes were assessed. Production characteristics assessed included live weight gains, intake, P2 backfat thickness and feed conversion ratio. Main observed effects were associated with slaughter weight and its interaction with sex type. Rates of change in parameters measured were described. Growth and feed conversion ratio were described using linear models while cumulative feed intake was described using 2nd order polynomials. Carcass characteristics assessed included carcass weight, dressing percentage, carcass length, ham length, ham circumference, chest depth, backfat thickness measurements, muscle depth, eye muscle area, subcutaneous fat area, intramuscular fat area as well as ratios of eye muscle to subcutaneous and intramuscular fat area. The main statistical differences observed were for slaughter weight. Significant sex type differences were observed for dressing percentage and some fat and muscle depth measurements. Meat quality characteristics assessed included colour measurements, tenderness, drip loss and water holding capacity. Main differences observed were for slaughter weight. Carcass yields were assessed in terms of absolute and percentage yields of commercial cuts as well as yield of processable lean meat. In terms of the absolute and percentage yields of the commercial cuts, the main statistical differences observed were for slaughter weight. Changes in cut yield with increased slaughter weight are described using regression analysis. In terms of yields obtained for processable lean meat, the main statistical differences observed were for slaughter weight. Sex type differences were only observed for percentage belly and topside processable lean meat and percentage brine uptake of belly bacon, whole gammon ham and topside gammon. Genotypic differences were observed for percentage yield of processable lean meat of the neck and whole gammon and percentage fresh to smoke losses of back bacon and whole gammon ham. Sensory attributes were assessed using gammon ham, belly bacon and fresh loin. Observed slaughter weight differences were inconsistent and did not appear to change with an increase in slaughter weight. Once meat was processed, most sensory differences were no longer observed. Increased slaughter weight generally led to increased juiciness and decreased tenderness. It is therefore concluded that the current South African pig genotypes have the ability to maintain high growth rates for a much longer time and therefore can be slaughtered at a higher weight without detrimental effect on production efficiency, carcass and meat quality characteristics, yields of commercial and processable lean meat, processing characteristics and ultimately sensory characteristics of the meat produced.
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    Hermetia illucens Larvae Reared on different substrates in broiler quail diets : effect on physicochemical and sensory quality of the quail meat
    (MDPI, 2019-08-02) Cullere, Marco; Woods, Michael Josias; Van Emmenes, Liesel; Pieterse, Elsje; Homan, Louwrens Christiaan; Zotte, Antonella Dalle
    This research aimed at improving the fatty acid (FA) profile of Hermetia illucens larvae (HI) and evaluating the effects of their inclusion in growing broiler quails’ diets on the meat physicochemical quality, including detailed amino acid (AA) and FA profiles, sensory traits, and retail display. HI larvae were reared on two different substrates: layer mash (HI1) and 50:50 layer mash/fish offal (HI2). A total of 300 10-day-old quails were allocated to the three dietary groups (five replicates/each): a soybean meal-based diet was formulated (Control), and two other diets were formulated that included either 10% HI1 or HI2. Quails were fed the experimental diets until slaughter. Diets were formulated to be isonitrogenous and isoenergetic. Breast meat quality was affected by the dietary treatments, which displayed different proximate compositions and AA and FA profiles. Meat physical quality, sensory profile, and retail display remained unaffected for the most part. Overall, results showed that it is possible to improve the FA profile of the HI-fed quails’ meat and thus lipid quality through substrate modulation of the HI’s diet.
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    Inclusion of Hermetia illucens larvae reared on fish offal to the diet of broiler quails : effect on immunity and caecal microbial populations
    (Czech Academy of Agricultural Sciences, 2020-05-30) Pasotto, Daniela; Van Emmenes, Liesel; Cullere, Marco; Giaccone, Valerio; Pieterse, Elsje; Hoffman, Louwrens Christiaan; Zotte, Antonella Dalle
    Hermetia illucens (black soldier fly, BSF) larvae meal has shown to be a good protein source in monogastric animal diets, but published data regarding its immunomodulatory properties is limited. For this purpose, a study has been conducted to evaluate the effects of larvae meal on selected immune parameters and caecal bacterial counts of broiler quails. Hermetia illucens larvae were reared on two substrates (100% chicken feed, BSF-M, or 50% chicken feed + 50% fish offal, BSF-F) in order to manipulate the fatty acid profile of larvae meal by increasing the long-chain omega-3 (n-3) polyunsaturated fatty acids which are known for their immunomodulatory properties. For immunological purposes, a total of 60 birds were randomly allocated to three dietary treatment groups (n = 20/treatment): control quail diet (CON), or quail diets including 10% of BSF-F or BSF-M larvae meal. Blood was collected 27 and 37 days after the trial commenced to determine the humoral immune response, serum lysozyme concentrations, serum bactericidal activity and protein fractions of the serum. The dietary inclusion of BSF-M meal resulted in an increased secondary humoral immune response compared to the CON treatment group (P < 0.01). Quails in the BSF-F treatment had significantly higher serum lysozyme activity compared to quails in the CON and BSF-M treatment group. Both larvae meals significantly increased cell-mediated immunity on day 37 (P < 0.001) but they had no effect on serum bactericidal activity. Both larvae meal sources resulted in higher α2-globulin levels on both sampling days, whereas γ-globulin levels were significantly lower in quails with the BSF-F treatment on day 27. Dietary treatments had no significant effect on caecal bacterial counts. In conclusion, the present study showed that the larvae meal had immunostimulatory effects in quails, but the rearing substrate of larvae strongly influenced the immunostimulatory properties of the larvae meal.