Research Articles (Animal Sciences)
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- ItemEffects of Saccharomyces cerevisiae, medium and forage type and their interactions on in vitro ruminal fermentation(Elsevier, 2020-09) Russouw, A.; Chevaux, E.; Chaucheyras-Durand, F.; Esposito, G.; Raffrenato, E.The objective of this study was to investigate the effects of a live yeast, Saccharomyces cerevisiae CNCM I-1077, at four doses (0, 1×105, 1×106 and 1 × 107 cfu/mL) according to the reducing medium used [Goering-Van Soest (GV), McDougall (MD) or Kansas State (KS)] on in vitro ruminal neutral detergent fibre digestibility (NDFd), rate of digestion of NDF (kd), organic matter digestibility (OMd), dry matter digestibility (DMd), pH as well as volatile fatty acids (VFA) concentration, using two forages (oat hay and wheat straw) with differing chemical composition. The maximum in vitro NDFd, DMd, OMd as well as kd were obtained with dose 1 × 106 cfu/mL, although differences between doses were not always significant. The pH estimates were the lowest with the 1 × 107 cfu/mL dose, but the differences were not all significant; however, 1 × 107 cfu/mL corresponded to significantly lower pH estimates compared to the control and 1×105 (6.51 vs. 6.60 and 6.59, respectively). The decrease in pH was accompanied by an increase in VFA concentrations as the yeast dose increased. The KS medium resulted in the lowest digestibility estimates, pH estimates as well as kd, regardless of yeast dose. The 1 × 106 cfu/mL was the better performing yeast dose in vitro resulting in higher digestibility estimates which indicates the yeasts ability to stimulate the microorganisms within the rumen by beneficially modifying rumen environment, thus promoting microbiota activity. The MD and GV media provide better environments for fermentation than the KS medium, resulting in higher in vitro NDFd, DMd, OMd, pH estimates as well as rate of NDF digestion. The MD and GV are also the media that resulted in more consistent results when analysing the effects of the live yeast. Our data suggest that the in vitro conditions have to be carefully chosen to be able to demonstrate rumen fermentation shifts with the use of live microbial additives.
- ItemUse of pawpaw (Carica papaya) seed in tilapia sex reversal(Reviews in Agricultural Science, 2020-10-18) Omeje, Victor Okonkwo; Lambrechts, Helet; Brink, DanieTilapia breeds effortlessly in captivity, with this attribute which is considered as the “Achilles heel” of the species, because it predisposes pond systems to overcrowding and low weight at harvest. Efforts to mitigate this shortcoming include mono-sex culture using exogenous hormone to reverse the sex of sexually undifferentiated fish. This is premised on the fact that improvement in the growth by mono-sex culture will lead to shortened production times and a more uniform weight at harvest, which will ultimately benefit the producers. However, the use of exogenous hormones in aquaculture has recently raised concerns about the effect on farm workers, consumers and on the environment. Recently research has focused on the use of substances of plants origin which mimic the action of hormones as a potential approach to achieve sex reversal in fish. Pawpaw (Carica papaya) seed contains phytochemicals that hold great promise as a sex reversal and a reproductive inhibition agent in aquaculture. The purpose of this study was to conduct a systematic review of the relevant literature on the possibility of using a less harmful phytochemicals abundant in the plant to effect sex reversal of sexually undifferentiated tilapia.
- ItemEffects of honeybush (Cyclopia subternata) extract on physico-chemical, oxidative and sensory traits of typical Italian salami(Wiley, 2020-02-18) Smit, Paula; Cullere, Marco; Zotte, Antonella Dalle; Balzan, Stefania; Hoffman, Louwrens Christiaan; Novelli, EnricoHoneybush (Cyclopia subternata Vogel) is an indigenous South African shrub enjoyed as hot brewed tea. "Unfermented" honeybush is also a potential antioxidant bioactive extract for foodstuffs due to its polyphenol content. The effect of "unfermented" honeybush extract (Hob; 0.5%) was evaluated in typical Italian salami and compared with nitrate (Nit; 100 mg/kg) and a control (Ctl; without nitrate or honeybush). After 35 days of ripening, Hob had a higher (p < .01) water activity (0.928), compared with Ctl (0.923) and Nit (0.924). Final pH (5.35-5.24) was not affected by treatments. Lower lipid oxidation was observed in Hob and Nit treatments (p < .001) compared with Ctl. Internal color and odor intensity were similar among treatments. Salami with honeybush extract had less spontaneous outer surface mold growth whereas the Ctl showed intermediate growth (p < .05). Honeybush extract seems a promising natural ingredient with antioxidant action.
- ItemPolyunsaturated 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, CletosThe 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.
- ItemDiscriminating muscle type of selected game species using near infrared (NIR) spectroscopy(Elsevier, 2019-11-02) Dumalisile, Pholisa; Manley, Marena; Hoffman, LouwrensIn this study near infrared (NIR) spectroscopy was used to discriminate between different muscle types within each species of selected game animals, and to classify species regardless of the muscle. Muscle steaks from longissimus thoracis et lumborum (LTL) located at the 6th rib of the carcasses, infraspinatus (IS) and supraspinatus (SS) located on the forequarter, and biceps femoris (BF), semitendinosus (ST) and semimembranosus (SM) located on the hindquarter of impala and eland species; and samples from fan fillet (FF), big drum (BD), triangle steak (TS), moon steak (MS) and rump steak (RS) of ostrich species were scanned with a handheld NIR spectrophotometer in the spectral range of 908–1700 nm. Spectra were pre-treated with different pre-processing methods and classification models were developed using partial least squares discriminant analysis (PLS-DA). Classification accuracies were higher when the muscles were grouped according to their anatomical location in the carcass, than attempting to classify them separately. Classification accuracies ranging from 85.0 to 100% were achieved throughout, with forequarter muscles yielding the highest classification accuracy rate for both impala and eland species. Furthermore, when the species were discriminated regardless of muscles, PLS-DA models pre-treated with SNV-Detrend and Savitzky-Golay 1st derivative yielded accuracies of 97, 81 and 92% for eland, impala and ostrich, respectively. These results indicate that NIR spectroscopy can be used for the authentication of game meat, specifically impala, eland and ostrich. Furthermore, it was easier to discriminate species regardless of the muscle used than different muscles within each species.