Scielo RSS <![CDATA[South African Journal of Animal Science]]> vol. 47 num. 6 lang. en <![CDATA[SciELO Logo]]> <![CDATA[<b>Castration of male livestock and the potential of immunocastration to improve animal welfare and production traits: Invited Review</b>]]> Growing consumer awareness about animal welfare has led to the assessment of the impact of common farming practices, such as physical castration, on animal well-being under production conditions. Physical castration is used in livestock industries to prevent indiscriminate breeding, control aggression, and improve meat and carcass quality. In terms of animal welfare, physical castration causes pain, decreased growth performance, infection, and mortality. An alternative approach to castration is thus warranted that will ensure optimal growth without compromising the castrated animal's wellbeing. Immunocastration has proved to be an effective method of suppressing the development and functioning of the reproductive system in various domesticated and wildlife species. The effect of immunocastration on production performance is well-documented for both swine and cattle. Although ram lambs used for meat production are often physically castrated, information regarding the potential application of immunocastration in sheep is limited. However, immunocastration may potentially improve the welfare, performance, and meat quality of ram lambs used in commercial meat production systems. The purpose of this review is to compare the application and the effects of immunocastration on male livestock to highlight and motivate the need for further research into its use on ram lambs. <![CDATA[<b>Processing of South African biltong - A review</b>]]> South Africa has been producing biltong for many years and its popularity is increasing locally and internationally. Biltong is commonly grouped with other dried meat products from around the world, but with its unique production method and expanding economic value, an increase in knowledge on the subject is in high demand. In this paper, biltong processing and quality are reviewed to highlight areas in which knowledge is still lacking. It shows that biltong processing varies resulting in the wide physico-chemical characteristics reported in the literature. However, consumer preference is still an area that lacks scientific data/evidence. Previous research on biltong has focused on the pathogenic microorganisms and not on its spoilage and shelf-life. Moreover, the effects of the various processing methods on the physico-chemical characteristics and resulting microbial stability has not been investigated. Knowledge of these could enable an increase in the quality of biltong. <![CDATA[<b>Effects of Silymarin <i>(Silybum marianum) </i>supplementation on milk and blood parameters of dairy cattle</b>]]> The present study was conducted to investigate the effect of dietary silymarin on milk yield, milk fat, and certain blood parameters of dairy cattle. Silymarin is a naturally accepted hepatoprotectant that is used in the treatment of liver diseases in human beings, and has been tested in dairy cows during peripartum. Animals are subject to subclinical fatty liver. In the first part of the study, the silymarin (20 g/head/day) was supplemented to dairy cattle rations in the last 21 days (peripartum) of pregnancy. In the second part of study, silymarin was added to the rations of Holstein dairy cows for three weeks postpartum. A total of 40 Holstein dairy cows at 2nd lactation with 550-600 kg live weight and average body condition score of 3.5 were used. Dairy cows were randomly separated into two treatment groups (20 cows in each). The first group was control (no addition) and the second group was treatment (silymarin supplemented) group. Treatments significantly increased milk yield, but decreased milk protein. Postpartum bodyweight loss was significantly less in the silymarin group than in the control group. Differences in postprandial plasma triglyceride (TRG) and total cholesterol (TC) levels were found to be significant. Plasma alanine aminotransferase (ALT) and total protein (TP) values of the groups were also significantly different. As a result, it was observed that silymarin supplementation of the ration did not have side effects, and peak milk yields could be achieved earlier with silymarin treatment. Application of silymarin is believed to be useful. It was also observed that silymarin treatments speeded up the metabolic adaptation process of the dairy cows at the beginning of lactation. It was suggested that silymarin should be used in transition periods of dairy cattle. <![CDATA[<b>Effects of probiotics on growth performance, blood parameters, and antibody stimulation in piglets</b>]]> The study investigated the effects of probiotic bacteria (Lactobacillus reuteri ZJ625, Lactobacillus reuteri VB4, Lactobacillus salivarius ZJ614, and Streptococcus salivarius NBRC13956) administered as direct-fed microorganisms on growth performance and blood parameters of weaned piglets. Forty-five weaned piglets were divided into five treatments: antibiotic (PC), no antibiotic and no probiotic (NC), probiotic (P1), probiotic (P2), and combination of probiotics (P3). Fecal and ileum samples were collected for microbial count analysis. Blood samples were also collected from the animals at the end of the trial for the hematological and biochemical analysis and the ability of the probiotics to stimulate immunoglobulin G (IgG). Supplementation of probiotics had no effect on feed intake (FI). However, average daily weight gained (ADG) in the P3 treatment was higher than in other treatments and lowered the value of feed conversion ratio (FCR) of weaned piglets. Microbial count of fecal samples did not differ in all the treatments while ileum samples had lower enteric bacteria in P3 treatment when compared to other treatments. Concentration of albumin, globulin, neutrophils and basophils were higher in the NC treatment when compared to other treatment groups. The IgG concentration was highest in P3 compared to other treatments. Results suggested that probiotics have beneficial effects on growth performances, blood parameters, and IgG stimulation of weaned piglets. This advocates that probiotics will offer a significant benefit in pig farming by reducing the risk of post weaning diarrheal syndromes, and therefore enhance pig industry's economy. <![CDATA[<b>Effects of dietary physical form and dietary inclusion of probiotic and enzyme on growth performance, cellular and humoral immunity, and relative weights of lymphoid organs at early period of broiler chickens fed triticale-based diets</b>]]> The aim of the present study was to investigate interactions between feed form and dietary inclusion of probiotics (live organisms) and enzymes on growth performance, cellular and humoral immunity, and relative weights of lymphoid organs of broiler chicks fed a triticale-based diet. A total of 640 broiler chicks were allocated to eight treatments when they were one day old, with four replicates (n = 20 chicks in each). The dietary treatments consisted of feed form (pellets or mash) and dietary supplementation with or without a Bacillus-based probiotic (0.03% diet) and enzyme (carbohydrase, 0.05% diet) in a 2 × 2 × 2 factorial arrangement. Feed conversion ratio (FCR) was calculated based on feed intake (FI) and weight gain (WG). The WG of the broiler chicks fed the pelleted diets containing the enzyme and probiotic (alone or in combination) was greater than that of the birds fed the mash diets without these additives. Significant interaction effects of the enzyme and probiotic on FCR and FI were observed in the starter period. The heterophil : lymphocyte (H : L) ratio of the chicks fed the pelleted diet containing the enzyme and probiotic was lower than that of the birds fed the other diets. The cellular immunity of the birds fed this diet increased after 24 hours, as shown by the results of a challenge experiment with dinitrochlorobenzene (DNCB) or an injection of phytohemagglutinin (PHA). In conclusion, feed form and supplementation of a triticale-based diet with feed enzymes and probiotics can greatly improve the growth performance and immunity of broiler chicks. <![CDATA[<b>Effects of <i>Prosopis laevigata </i>pods on carcass characteristics, non-carcass components, meat quality, fatty acid profile and sensory attributes</b>]]> It was hypothesized that feeding mesquite pods to male Rambouillet lambs would have no negative effects on carcass characteristics, meat chemical composition and fatty acid composition of Longissimus thoracis et lumborum (LTL). Twenty-one male lambs (2.5 months old and 21 ± 1.44 kg bodyweight) were randomly assigned to one of three experimental diets, two of which replaced maize grain and stover with mesquite pods (Prosopis laevigata) (PL): 0 g PL/kg feed (PL0), 250 g PL/kg feed (PL250) and 500 g PL/kg feed (dry matter basis). The feeding trial lasted 72 days. Carcass traits, chemical composition, fatty acid profile, and sensory characteristics of meat were measured. Carcass linear dimensions, non-carcass components, digestive tract and offal, compression value, and chemical composition of meat were similar in all treatments. Dietary inclusion of PL decreased carcass shrinkage loss. Lambs fed PL500 had better muscle conformation and degree of fat. Meat produced by PL-fed lambs was well accepted by panellists who judged meat appearance, colour, flavour, juiciness, toughness, and stringiness. In lambs fed PL0, the LTL muscle was lighter and yellower than that of animals fed PL250 and PL500 diets. Fatty acid composition was altered. The PL0 diet resulted in lower percentages of total trans fatty acids (TFA) and saturated fatty acids (SFA) and higher percentages of most unsaturated fatty acids (UFA) and polyunsaturated fatty acids (PUFA) n-6 compared with PL250 and PL500 diets. Mesquite diets of up to 500 g/kg dry matter (DM) for growing lambs improved carcass quality and nutritional parameters of the meat. <![CDATA[<b>Carcass and meat quality of Boer and indigenous goats of South Africa under delayed chilling conditions</b>]]> This study was conducted to evaluate the carcass and meat quality of Boer goats and unimproved indigenous goats of South Africa, under delayed chilling conditions. Ten goats per breed were used for the study. The goats were slaughtered according to standard abattoir procedures. The dressed carcasses were held at 10-15 °C for 6 hours before chilling at 4 °C until 24 hours (delayed chilling). The pH/temperature values, instrumental colour (CIE L*, a*, b*, chroma and hue angle), surface myoglobin pigments (deoxyglobin, oxyglobin and metmyoglobin), water-holding capacity (WHC), thawing loss, cooking loss, sarcomere length, and Warner Bratzler shear force (WBSF) values were evaluated on samples of the m. longissimus dorsi (LD) and the m. semimembranosus (SM). Carcasses of Boer goats were heavier and had higher chilling loss than those of indigenous goats. There were no breed differences in dressing percentages, pH/temperature values or meat quality characteristics. Overall, the mean ultimate pH values (5.75-5.80), were marginally higher than the recommended pH for desirable eating quality. However, the mean L* (36.3-40.2), a* (18.0-18.8), WHC (0.35-0.39) and metmyoglobin (16.3-18.8%) values were within the range that is acceptable for normal meat. On average, LD samples were tender (WBSF values of 4.43 ± 0.40 kg), but SM samples were marginally tough (WBSF values of 8.45 ± 0.54 kg). This study shows that delayed chilling could be a useful strategy in improving the colour and tenderness of goat meat.