Scielo RSS <![CDATA[South African Journal of Animal Science]]> vol. 46 num. 3 lang. en <![CDATA[SciELO Logo]]> <![CDATA[<b>Effects of replacing marine fishmeal with graded levels of Tra Catfish by-product protein hydrolysate on the performance and meat quality of pigs</b>]]> A feeding trial was carried out to evaluate the effects of replacing fish meal (FM) with Tra Catfish (Pangasius hypophthalmus) by-product protein hydrolysate (TPH) on performance and carcass quality in pigs. Forty crossbred castrated (Yorkshire x Landrace) male pigs with an initial average bodyweight of 22.8 ± 1.5 kg were allocated to 40 individual pens in a randomized complete block design with eight replications. The pigs were fed a control diet (TPH0) with FM as sole protein supplement. In the experimental diets, 100% (TPH100), 75% (TPH75), 50% (TPH50) and 25% (TPH25) of the crude protein (CP) from FM was replaced by the CP from TPH. The results showed no significant differences in average daily feed intake (ADFI) in all treatments during the growing and finishing phases. However, daily weight gain (ADG) was higher in TPH75 (655 g/day) and TPH100 (663 g/day) than in TPH0 (639 g/day). Feed conversion ratio (FCR) was improved with higher inclusion of TPH in the diets. Carcass yield and dressing percentage were not affected by treatments, but abdominal fat and backfat thickness were higher and in the loin-eye area lower in TPH100 compared with TPH0. Polyunsaturated fatty acids (PUFA), ether extract (EE) contents and meat colour values a* (redness) in the longissimus dorsi muscle increased with TPH replacement level. Feed costs were 10% lower in TPH100 compared with TPH0. In conclusion, replacing FM with TPH improved the performance, but resulted in an increase in backfat thickness and fat content of meat. However, because of reduced feed costs, complete replacement of FM would still be profitable for pig producers in Vietnam. <![CDATA[<b>Effect of sow age on the apparent total tract digestibility of nutrients in the diet</b>]]> The objective of this research was to evaluate the effect of sow age on apparent total tract digestibility of nutrients and the concentration of metabolizable energy in the diet. The experiment was carried out on 20 gestating sows, divided into two groups: Group I - 10 sows in first pregnancy (131 ± 4.5 kg) and Group II - 10 sows in fourth pregnancy (225 ± 8.2 kg). Sows in the two groups were fed identical diets for sows during early pregnancy. The total collection of faeces began on day 30 of pregnancy and lasted eight days. Sows in the fourth pregnancy had greater digestibility coefficients of dry matter (4.1 percentage units), organic matter (3.4 percentage units), crude protein (5.5 percentage units) and crude fibre (6.2 percentage units) than sows in the first pregnancy. The total tract digestibility of ether extract, starch and sugars was not affected by pig age. The metabolizable energy, determined according to the content of digestible nutrients, in the sow diet in fourth pregnancy was 0.7 MJ/kg higher than in the diet of sows in their first pregnancy. Results of this research indicate that sow age should be considered when formulating diets during early pregnancy. <![CDATA[<b>Fatty acid profile and health lipid indices in the raw milk of ewes grazing part-time and hemp seed supplementation of lactating ewes</b>]]> This experiment was designed to evaluate the effects of the feeding system (indoor or part-time grazing) of ewes and dietary supplementation with hemp seed (non-drug varieties of Cannabis sativa L.) on milk production and the composition of milk fatty acids (FAs). The experimental diets were constituted as a 2 x 2 factorial arrangement of feeding system (I: indoors and receiving 1400 g dry matter (DM) grass hay/d or pasture grazing (PG)-4 h/day + 700 g DM grass hay/d), and with or without hemp seed (Hs) supplementation (-Hs = no hemp seed vs. +Hs = 175 g/d hemp seed). All animals received 700 g DM/day of a concentrate for lactation. Feeding the PG diets increased raw milk production and yields of fat, protein and lactose. Feeding +Hs increased fat-corrected milk, milk fat content and fat yield significantly while the combination of +Hs and PG increased fat-corrected milk and fat yield significantly. Milk protein content was not affected by dietary factors. Feeding the I diets increased the proportion of short-chain FAs (C4:0 -C10:0), at the expense of medium-chain FAs (12 to 17 C units). Feeding +Hs decreased the proportion of short-chain FAs, medium-chain FAs and hypercholesterolaemic FA (sum of C12:0, C14:0, C16:0) and increased the trans-vaccenic acid (C18:1 t11, VA), α-linolenic acid (C18:3 n-3, ALA), conjugated linoleic acid (CLA), eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) concentrations in milk fat significantly. The combination of hemp seed and part-time grazing produced the highest proportion of c9,t11 CLA, t10,c12 CLA and n-3 FA (sum of ALA, EPA, DHA) in milk fat. The polyunsaturated fatty acid (PUFA)/saturated fatty acid (SFA) ratios in the milk from ewes grazing part time were significantly higher, whereas the atherogenicity index (AI), thrombogenic index (TI) and linoleic acid (LA)/ALA ratio were significantly lower compared with the milk of indoor-fed ewes. Supplementing with +Hs has a similar effect of increasing the PUFA/SFA ratio and lowering of the AI, TI and LA/ALA ratio. It was concluded that pasture grazing combined with hemp seed had a synergistic effect on milk production and fat yield without altering the milk protein content in ewes. This combination has favourable effects on milk FA profile from the human consumer's point of view by increasing the nutritional quality of milk. <![CDATA[<b>Effects of dietary supplementation of Chinese herb medicine mixture on rumen fermentation, nutrient digestion and blood profile in goats</b>]]> Twenty adult goats, fitted with ruminal cannulae, were used to investigate the effects of dietary supplementation of Chinese herbal medicine (CHM) mixtures on rumen fermentation, nutrient digestion and blood profiles. The wethers were assigned equally to one of the two dietary treatments according to a randomized controlled trial design. One dietary treatment was the basal diet, while the other was the CHM mixture diet consisting of the basal diet and the CHM mixture. Chinese Mosla, Atractylodes rhizome, Officinal Magnolia bark, white hyacinth bean and Liriope root tuber were mixed with a weight ratio of 8:4:4:4:5 to make up the CHM mixture. This mixture was added to the basal diet at 15 g/kg feed. The dietary supplementation of the mixture increased ruminal fluid concentrations of acetate, butyrate and total volatile fatty acids, and the ruminal activities of avicelase, carboxymethyl cellulase, cellobiase and xylanase. It also improved the ruminal effective degradability of dry matter, organic matter and amylase-treated ash-free neutral detergent fibre from the forage, apparent total tract digestibility of gross energy, dry matter, organic matter, crude protein, amylase-treated ash-free neutral detergent fibre, ash-free acid detergent fibre and calcium. Whole blood pH and concentrations of actual bicarbonate, buffer excess and magnesium ion, plasma concentrations of leptin, total protein, albumin, globulin, C-reactive protein, immunoglobulin A/G/M and complement 3/4 increased. Furthermore, plasma activities of nitric oxide synthase, glutathione peroxidase and total superoxide dismutase and plasma total antioxidative capacity increased. However, plasma concentrations of adrenocorticotropic hormone, aldosterone, cortisol, glucose, urea nitrogen and lactic acid and plasma activities of alanine transaminase, creatine kinase and lactate dehydrogenase decreased. These results indicated that the dietary supplementation of the CHM mixture exerted some positive regulating effects on the nervous system, the endocrine system and the immune system of goats, thus improving the functions of immunity and antioxidation, as well as the digestion and metabolism of nutrients. However, the CHM mixture did not affect their rumen fermentation patterns. <![CDATA[<b>Ovulatory response and embryo quality in Katahdin ewes supplemented with palm oil</b>]]> The aims of this study were to evaluate the superovulatory response (SR), embryo quality and embryonic development in Katahdin ewes that received a dietary supplement of palm oil (PO). Ten ewes were assigned to receive 35 g palm oil (n = 10, PO3) and 10 to receive 70 g palm oil (n = 10, PO6) for 25 days. On day 0, the ewes were synchronized with 0.3 mg progesterone-releasing devices (CIDR-G®). From days 6 to 9, the donors were superovulated with 200 mg follicle-stimulating hormone (FSH) (Folltropin-V®) at decreasing doses every 12 hours (40 - 40, 30 - 30, 20 - 20 and 10 - 10 mg/ewe). On day 8, the devices were removed and donors were mated twice with fertile rams at 12-h intervals. Seven days after mating, the embryos were recovered and evaluated for their stage of development and quality grade (1 = excellent, 2 = good, 3 = bad and 4 = degenerated). In addition, on days 0, 7 and 15, blood samples were taken to determine cholesterol, triglycerides, insulin and insulin-Iike growth factor-1 (IGF-1) concentrations in serum blood. Using chi-square and t-tests, the superovulatory response (SR), ovulation rate (OR), total embryonic structures (TES), transferable embryos (TE), degenerated embryos (DEs) and developmental stage and quality were evaluated. No significant differences were observed between treatments for SR, OR, TES and TE variables or for cholesterol, triglycerides, insulin and IGF-1 concentrations. There were differences in the numbers of DE, as well as a trend for more homogeneous developmental stage in the embryos of ewes supplemented with PO6, as well as a higher number of quality 1 embryos and lower numbers of quality 3 and 4 embryos. Palm oil supplementation could be a recommendable practice to improve the quality of embryos and homogenous developmental stage (morula and blastocyst). <![CDATA[<b>The response of broiler breeder hens to dietary balanced protein</b>]]> Two basal feeds (118 and 175 g protein/kg) with similar balanced amino acid mixtures were appropriately blended to produce six experimental diets differing in protein. These were fed for six weeks to 180 broiler breeder hens (Ross 308) housed in individual cages from 26 w of age. A 13 h photoperiod was applied. Half the birds were restricted to 160 g of feed/d, whilst the others were fed ad libitum. The treatments were randomly allocated within six blocks. At the end of the six-week period the mean voluntary intake of the ad libitum-fed birds was 169 g/d whereas the intake of hens on feed restriction was 155 g/d. In spite of the range of protein intakes from 18.5 and 28.8 g/bird, no differences were observed in rate of laying between the two feeding strategies or dietary protein levels, nor were there differences in the proportions of yolk or albumen between these treatments. Egg weight, egg output and weight gain increased with protein intake as did energy retention (kJ/d) whereas heat output (kJ/d) decreased as protein intake increased. Even though dietary protein intake had no effect on rate of lay, the resultant decrease in heat output at high protein intakes suggests that this might be a useful strategy to consider for overcoming mild heat stress. <![CDATA[<b>Effects of <i>Thymus vulgaris </i>and <i>Mentha pulegium </i>on colour, nutrients and peroxidation of meat in heat-stressed broilers</b>]]> This study was designed to investigate the effects of Thymus vulgaris (thyme) and Mentha pulegium (mentha) powders on meat colour, nutrient composition and malondialdehyde (MDA) where broiler chickens were under heat stress. Two hundred one-day-old male chicks were used in a completely randomized design with four treatments and five replicates each (10 birds per replication). Treatments were the control diet, 0.5% mentha, 0.5% thyme and 0.5% mixture of the two plants. The results showed no effect of dietary supplements on thigh meat redness and yellowness. Both plant products diminished the thigh lightness significantly compared with the control. No significant differences between treatments were observed for the ash, ether extract and crude protein content of the thigh muscle. Supplementation of thyme and mentha separately or together increased the moisture of the thigh muscle significantly, compared with the control. The combination of the plant products resulted in a higher thigh pH and significantly lower malondialdehyde (MDA) concentration in the thigh muscle compared with the control. In conclusion, dietary supplementation of thyme and mentha separately or in combination improved the meat quality of broiler chickens under heat stress through decreasing the MDA concentration and increasing the pH and moisture content of the thigh muscle. <![CDATA[<b>Interactions of genotype, housing and dietary calcium in layer performance, eggshell quality and tibia characteristics</b>]]> The study was designed to evaluate the interactions in performance, eggshell quality and tibia traits of two laying hen genotypes, namely a commercial hybrid, Lohmann (LSL), and a traditional breed, the Czech Hen (CH), housed in conventional cages and on litter, and fed two levels of dietary calcium (Ca) (3.5% vs. 3.0%). A significant interaction between genotype, housing and Ca was determined in egg weight. The heaviest eggs were laid by LSL hens housed in cages and fed 3.0% Ca (61.8 g), and the lightest laid by CH, also in cages on 3.0% Ca (47.3 g). Eggshell strength and shell weight were significantly affected by three-way interaction. Czech hens kept in cages and fed 3.0% Ca produced the strongest shells (4480 g/cm²), whereas the CH in cages on 3.5% Ca had the weakest (3665 g/cm²) shells. Hens housed on litter had significantly stronger tibias than hens housed in cages (485 vs. 397 N). With respect to genotype, tibias were stronger in CH. Housing and level Ca in feed had a significant effect on tibia weight. However, none of these factors affected tibia thickness or ash content. Tibia Ca content was higher in caged birds than in those on litter. The results of the study show that interaction between housing, genotype and Ca resulted in large differences in measurements of egg weight and eggshell quality. Tibia characteristics were less affected by the treatments, and no interactions were evident in the variables. <![CDATA[<b>Effects of stocking density on growth performance, carcass grade and immunity of pigs housed in sawdust fermentative pigsties</b>]]> This study determined the effect of space allowance on performance, carcass grade and physiological variables of pigs reared in sawdust fermentative pigsties. A total of 699 crossbred (Landrace χ Yorkshire χ Duroc) pigs were housed in sawdust fermentative pigsties and assigned to one of three treatments at different growth stages, namely early grower pigs (EGP), weighing 15 - 40 kg; late grower pigs (LGP), weighing 40 - 75 kg; and finisher pigs (FP), weighing 75 - 110 kg, with three replicates. The three space allowances for each growth stage were 0.40, 0.55 and 0.70 m²/head for EGP; 0.55, 0.70 and 0.85 m²/head for LGP; and 0.85, 1.00 and 1.15 m²/head for FP. The feed intake in EGP was significantly decreased with increased stocking density. In LGP, the average daily gain (ADG) of pigs reared at high stocking density decreased linearly, whereas the feed conversion ratio increased significantly. The final bodyweight, ADG and feed intake in FP were lower with restricting space allowance. The carcass weight and backfat thickness were significantly higher with increased space allowance. The serum immunoglobulin G levels declined significantly with increased stocking density in all growth stages. The results of this study suggest that the space allowance for maximizing the growth performance and stabilizing immune response of pigs in sawdust fermentative pigsties is 0.55, 0.70, and 1.00 m²/pig for the bodyweight ranges of 15 - 40 kg, 40 - 75 kg, and 75 - 110 kg, respectively. <![CDATA[<b>Genome-wide identification of breed-informative single-nucleotide polymorphisms in three South African indigenous cattle breeds</b>]]> Access to genotyping assays enables the identification of informative markers that discriminate between cattle breeds. Identification of these markers can assist in breed assignment, improvement and conservation. The objective of this study was to identify breed informative markers to discriminate between three South African indigenous cattle breeds. Data from BovineSNP50 and GeneSeek Genomic Profiler (GGP-80K) assays were generated for Afrikaner, Drakensberger and Nguni, and were analysed for their genetic differentiation. Hereford and Angus were included as outgroups. Breeds were differentiated using principal component analysis (PCA). Single-nucleotide polymorphisms (SNPs) within the breeds were determined when minor allele frequency (MAF) was > 0.05. Breed-specific SNPs were identified using Reynolds Fst and extended Lewontin and Krakauer's (FLK) statistics. These SNPs were validated using three African breeds, namely N'Dama, Kuri and Zebu from Madagascar. PCA discriminated among the breeds. A larger number of polymorphic SNPs was detected in Drakensberger (73%) than in Afrikaner (56%) and Nguni (65%). No substantial numbers of informative SNPs (Fst > 0.6) were identified among indigenous breeds. Eleven SNPs were validated as discriminating the indigenous breeds from other African breeds. This is because the SNPs on BovineSNP50 and GGP-80K assays were ascertained as being common in European taurine breeds. Lower MAF and SNP informativeness observed in this study limits the application of these assays in breed assignment, and could have other implications for genome-wide studies in South African indigenous breeds. Sequencing should therefore be considered to discover new SNPs that are common among indigenous South African breeds and also SNPs that discriminate among these indigenous breeds. <![CDATA[<b>Effect of micronized zeolite addition to lamb concentrate feeds on growth performance and some blood chemistry and metabolites</b>]]> This study was conducted to determine the effects of the addition of micronized zeolite (MZ) on the fattening performance, blood parameters, faecal ash and nitrogen levels of lambs fed concentrate feeds intensively. For two months 25 four-month-old Merino x Ile de France crossbred male lambs (21.1 ± 1.32 kg live weight) were fed 100 g alfalfa hay and a mixed concentrate diet containing 0%, 1%, 2% or 3% additional MZ. At the end of the study, bodyweight gain and feed consumption were not affected by the treatments. Similarly, the addition of up to 2% MZ to the diet did not affect slaughter weight, hot carcass or cold carcass weights, but they decreased at 3% MZ inclusion. No differences were observed between the groups in terms of blood urea nitrogen, plasma glucose, serum creatinine, triglyceride, sodium, potassium and chlorine concentration. However, serum total protein, calcium and phosphorus concentrations were affected by MZ supplementation. The addition of MZ to the ration did not affect the faecal dry matter content and total nitrogen level, yet it increased the ash content of the faeces. Consequently, it was demonstrated that the addition of up to 2% MZ to lamb grower feed does not have a negative impact on performance and carcass yield of the animals, but affects serum total protein, calcium and phosphorus concentrations.