Scielo RSS <![CDATA[South African Journal of Animal Science]]> vol. 44 num. 2 lang. pt <![CDATA[SciELO Logo]]> <![CDATA[<b>Influence of housing system on the growth and histological structure of duck muscles</b>]]> This study was aimed at determining the effect of housing systems on the growth, feed conversion ratio (FCR), meatiness and size of muscle fibres of Pekin (P44) and Muscovy (MR71) ducks. Each genetic group included 360 birds (180 males and 180 females). The ducks were divided into four experimental groups according to their sex and housing system: intensive system (IS) and outdoor system (OS). A significant effect of housing system on the final body weight and FCR value was noted only in P44 birds of both sexes, with OS birds having higher body weights than the IS birds. As a result, the OS MR71 drakes were characterized by a significantly higher slaughter yield, weight and content of breast muscles in the carcass. The OS MR71 ducks showed a lower slaughter yield and a higher content of leg muscles in the carcass compared to IS MR71 ducks. In contrast, the housing system had no significant effect on the meatiness of P44 ducks. A greater diameter of muscle fibres in both sexes of P44 ducks and in both sexes of MR71 ducks was observed in the OS compared to IS flocks. A greater cross section of muscle fibres was also noted in the ducks from the OS system, however with significant differences confirmed only in pectoralis superficialis and biceps femoris in MR71 drakes as well as in the biceps femoris of P44 drakes. These data show differences between duck genotypes and indicate the efficiency and potential of outdoor poultry systems. <![CDATA[<b>Index-in-retrospect and breeding objectives characterizing genetic improvement programmes for South African Nguni cattle</b>]]> The goals of this research were to document the historical selection applied by Nguni breeders that contributed to the national genetic evaluation scheme, and to offer prospective breeding objectives to guide future selection practices. Genetic selection differentials, weighted by number of offspring, and unweighted, were calculated for the recorded traits, and were used to quantify differences between natural and imposed selection. Index-in-retrospect methods were used to quantify differences between the traits in selection that were applied. Economic values for the prospective breeding objectives were derived through simulation. Results indicate that relatively little directional selection has been applied to Nguni as a breed, and that historically bulls and heifers were selected according to divergent criteria. Breeding objectives indicated that production, profitability and sustainability goals were largely complementary, but reflected a change from past selection practices. Breeders are advised to be intentional and consistent in the application of selection criteria. <![CDATA[<b>Nutritive value of ensiled pig excreta, poultry litter or urea with molasses or bakery by-products in diets for lambs</b>]]> The objective of this study was to evaluate the nutritive value of maize stover silage diets containing pig excreta (PE), poultry litter (PL) or urea as nitrogen (N) sources, and sugarcane molasses (MOL) or bakery by-products (BBP) as energy sources. The study was designed as a 6 x 6 Latin square with six ruminal cannulated Hampshire rams (56 ± 5.7 kg body weight) in a 3 x 2 factorial arrangement of treatments. The quality of silages was good because of acceptable pH (4.1), texture and odour. Gas production was higher for diets with silage containing PL than that containing PE (287 vs. 269 mL/g DM). The fermentation rate of diets with MOL was higher than with BBP (0.07 vs. 0.05/h). The in vitro degradation, feed intake and N excretion of diets that contained PL were higher than with PE silage. Feed intake for diets with silage that contained BBP and PL or PE was lower than that containing MOL. Rumen pH was increased in lambs fed diets with silage that contained urea (6.38) or PL (6.25), compared with lambs fed diets containing PE silage (6.04). Dry matter (DM) and organic matter (OM) disappearances were higher for diets with silage containing PL compared with those containing PE or urea (650 vs. 606 and 594 g/g DM; 620 vs. 574 and 594 g/g OM, respectively). The N retention and total tract digestion were similar for all treatments. It was concluded that diets with PL and MOL silage had higher nutritive values than those containing PE or urea. <![CDATA[<b>Effects of <i>in ovo</i> administration of amino acids on hatchability and performance of meat chickens</b>]]> The effects of in ovo amino acid administration on hatchability traits and post-hatch performance were studied using eggs from a meat-type breeder flock (Ross) at 38 weeks of age. On day 15 of incubation, five treatments were applied, consisting of six replicates with 16 eggs per replicate. The treatments consisted of a non-injected negative control; a positive control in which saline was injected; and three treatments with saline, containing 23.72 mg lysine, glutamine, glycine and proline (AA1); 23.60 mg arginine, glutamine, glycine and proline (AA2); and 28.76 mg lysine, arginine, glutamine, glycine and proline (AA3). The hatchability traits were incubation period, chick weight at hatch as an absolute value (CWT) and chick weight at hatch as a percentage of egg weight (CWTP), and the post-hatch performance traits were body weight gain (BWG), feed intake (FI) and feed conversion ratio (FCR). Measurements on the chickens were taken during the starter (1 - 21 days of age), finisher (22 - 35 days of age) and entire (1 - 35 days of age) experimental periods. In ovo amino acid treatments improved CWTP without affecting hatchability traits, and increased FI without altering the FCR of chickens during the entire experimental period. Chickens of the in ovo AA1 treatment had a higher FI than those of the control treatments during the finisher period. In ovo AA2 treatment increased CWT and BWG of the chickens during the starter period and entire experimental period and FI during the finisher period, when compared with those of the control treatments. In ovo AA2 treatment resulted in a longer period of incubation than those of other treatments. It was concluded that in ovo amino acid treatment increased CWTP and FI of chickens without affecting hatchability traits and feed efficiency and in ovo of AA2 treatment increased the incubation period, CWT and BWG when compared with those of control treatments during the entire experimental period. <![CDATA[<b>Effects of adiCox®AP and monensin on production parameters and quality of meat of slow-growing Hubbard JA 957 broiler chickens</b>]]> This experiment was conducted with 480 Hubbard JA 957 one-day-old broiler chicks to determine the effects of adiCox®AP, a plant coccidiostat, and monensin on production parameters and meat quality. The birds were randomly allocated to three experimental diets: (A) with the plant coccidiostat adiCox®AP; (M) with monensin, an ionophore coccidiostat; and (C) the control group without coccidiostats. The birds were reared on litter until 63 days of age. The bodyweight of chicks was recorded at the ages of 1, 12, 24, 42 and 63 days. The feed conversion ratio (FCR) and mortality ratio were calculated. There were no significant differences in bodyweight and FCR of birds tested across the experimental groups. In particular feeding groups, the mortality rate ranged from 2.60% to 4.33%, with the lowest number of deaths being noted in the groups receiving the plant coccidiostat (2.6%), whereas the highest mortality rate was recorded in the control group. The type of coccidiostat had no significant effect on the chemical composition of breast muscles. However, the leg muscles of the control chickens were characterized by a significantly higher content of protein (19.4%), compared with the groups receiving coccidiostats in the feed mixtures (19.1% in A and 18.6% in M). The plant coccidiostat effected a higher water-holding capacity (52.2%) and a lower cooking loss (6.9%) in the leg muscles of the birds. The administration of the plant feed supplement adiCox®AP significantly decreased the mortality rate of broiler chickens without compromising other production traits. The results also show that the applied plant preparation is an excellent alternative to antibiotic growth stimulants. <![CDATA[<b>Estimation of genetic parameters for body measurements and their association with yearling liveweight in the Makuie sheep breed</b>]]> The main objective of this study was to estimate the genetic parameters for body measurement and yearling live bodyweight traits in the Makuie sheep breed. The data set consisted of 2 144 lambs from 122 sires and 984 dams recorded in 21 years from 1989 to 2009 at the Makuie Sheep Breeding and Raising Station (MSBS). The traits that were studied were height at withers, height at rump, body length, heart girth, leg circumference and yearling weight. The analyses were carried out based on an animal model with the restricted maximum likelihood (REML) approach using a derivate-free (DF) algorithm. Six animal models were fitted, differentiated by including or excluding maternal effects, and with and without covariance between maternal and direct genetic effects. Ignoring the maternal effects, the direct heritability was estimated as 0.20, 0.24, 0.10, 0.14, 0.02 and 0.36 for height at wither, height at rump, body length, heart girth, leg circumference and yearling weight, respectively. The estimates were slightly higher when maternal effects, genetic or environmental, were ignored in the analyses. Using bivariate analysis, the estimates for additive genetic correlations ranged from 0.56 to 0.81 among the studied traits. A log-likelihood ratio test (LRT) was used to select the most appropriate univariate model for each trait. Based on LRT, the direct additive genetic and maternal permanent environmental effects were regarded as an important source of variation of the studied traits. The estimates of genetic parameters can be considered a basis for calculating selection indices for body measurements, as well as revealing their association with yearling bodyweight traits. <![CDATA[<b>Fatty acid profile of zebu beef cattle from the Central African sub-region</b>]]> This study analysed the meat fatty acid (FA) composition of three zebu breeds, Gudali (GU), White Fulani (WF) and Red Mbororo (RM), raised on savannah pasture and monitored in the commercial context of the Yaoundé abattoir. Samples of m. longissimus thoracis from 60 bulls belonging to the GU, WF and RM breeds were collected and analysed for fat and FA composition. The fat content of the meat was low, but similar across breeds (1.34 ± 0.912 g/100 g muscle, mean ± SD). Meat from the GU breed had higher C18:3n-3 and C22:5n-3 proportions and lower C18:0 and total saturated FA proportions than WF meat. Red Mbororo meat had an intermediate FA composition compared with the other breeds. The elongase and Δ9 desaturase indices were comparable among breeds. In summary, the results indicate that there are minimal differences in beef FA composition of the three breeds from the Central African sub-region. Additionally, based on the polyunsaturated FA (PUFA) proportion, 13.9% of the total lipids and n-6/n-3 PUFA ratio, 1.95, consumption of beef from these breeds could be beneficial to human health. This is possibly owing to the pasture feeding and low fat content of the beef. <![CDATA[<b>Association of polymorphism in the alpha-1-antitrypsin gene with milk production traits in Holstein dairy cows</b>]]> Alpha-1-antitrypsin (A1AT) as a strong protease inhibitor plays a major role in the protection of tissues against proteolytic destruction by neutrophil elastase. Existence of this protein in the mammary gland may increase the survival of milk proteins such as lactoferrin and lysozyme. The biological role of A1AT in tissues such as the mammary gland and results from previous quantitative trait loci (QTL) studies have provoked an investigation of A1AT as a candidate gene influencing milk production traits. The present study assessed the association of a single nucleotide polymorphism (SNP) at position 5504 of the A1AT gene with 305-day milk yield, milk fat and protein percentage and somatic cell score (SCS) in 408 Iranian Holstein cows. The polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) technique was used for genotyping. The effect of the genotype on the traits of interest was analysed using the general linear models (GLM) procedure of SAS software. The frequencies of alleles A and B were 0.633 and 0.367, respectively, and genotypes showed a significant deviation from Hardy-Weinberg equilibrium, which can be a result of selection for milk production traits. Results of association analysis showed a significant relationship between the SNP in the A1AT gene, and fat and protein percentage. Cows of genotype AB had higher milk fat percentage than those of genotype AA. Cows with genotype AA showed a lower milk protein percentage than those carrying genotype AB. When the association of this polymorphism with fat and protein percentage is considered, the SNP could be implemented as a marker in breeding programmes for these traits. <![CDATA[<b>A note on the effect of dietary supplementation with herbal extracts on sow and litter performance</b>]]> The aim of this study was to assess the efficacy of the phytogenic product, Ruchamax® (Ayurvet, India), on the productivity of sows and the performance of their first litters. Ruchamax® contains a blend of herbal extracts from Adrographis paniculata, Phyllanthus emblica, Curcuma longa, Zingiber officinale and Allium sativum. It was incorporated into a lactation concentrate mixture (E) at an inclusion rate of 1 kg per 1000 kg. A total of 40 primiparous sows (PIC) were allocated to two equal groups: untreated (control (C)) and herb-supplemented (E). Treatments were from day 1 to 28 of lactation. Nursing sows fed the herb-supplemented diet had significantly increased average daily feed intake (5.84 vs. 5.46 kg) and milk output (7.58 vs. 6.71 kg). The experimental factor had a positive effect on the condition of sows (lower reduction of thickness during lactation). Changes in backfat thickness (farrowing-weaning) were significantly different (-6.45 vs. -9.40 mm). There were no differences in initial litter size and litter birth weight (BW) between groups. The average BW of piglets was similar (ca. 1.6 kg) in both groups. The herb-supplemented diet affected 28-day litter weight (69.95 vs. 63.40 kg), average piglet body weight (7.27 vs. 6.74 kg) and daily litter growth rate (1.79 vs. 1.68 kg) significantly compared with the control. It can be concluded that the sows receiving an herb-supplemented diet were characterized by better productivity indices than the control group.