Scielo RSS <![CDATA[South African Journal of Animal Science]]> vol. 47 num. 2 lang. pt <![CDATA[SciELO Logo]]> <![CDATA[<b>Editorial: How to respond to reviewers' comments</b>]]> <![CDATA[<b>Alternative approaches to evaluation of cow efficiency</b>]]> The purpose of this study was to evaluate alternative expressions of genetic merit for cow efficiency. Weights of Pinzgauer cattle taken at birth, weaning, and maturity were extracted from the South African National Database. Average daily gain from birth to weaning (ADG) and cow weight (CWT) were analyzed with a multi-trait mixed model. The model included direct and maternal genetic effects, a permanent environmental effect attributable to dams on ADG, a direct genetic effect and a permanent environmental effect attributable to there being multiple observations from the same cow on CWT as random effects. Heritability estimates for direct and maternal additive effects on ADG were 0.27 ± 0.04 and 0.06 ± 0.02, respectively. The estimated heritability for CWT was 0.45 ± 0.06. Estimates of repeatability for ADG and CWT were 0.42 and 0.67, respectively. Estimated breeding values based on the preceding results and using the maternal genetic effect on ADG as a proxy for the direct genetic effect on milk production were combined in six indexes of cow efficiency. These indexes sought to increase output and decrease input simultaneously, to increase output holding input constantly, and to hold input constant while decreasing input. The diversity of emphasis applied across these indexes suggests the need for due diligence in developing breeding objectives for improvement of cow efficiency. Indexes that are consistent with the econometric definition of efficiency and seek to simultaneously increase output and reduce input are recommended. <![CDATA[<b>Prolactin-Rsal gene polymorphism in East Anatolian Red cattle in Turkey</b>]]> Prolactin (PRL) plays an important role in regulating mammary gland development, secreting milk, and expressing milk protein genes; making it a potential genetic marker and a candidate gene for production traits in dairy animals. The aim of the study was to determine by Polymerase Chain Reaction-Restriction Fragment Length Polymorphism (PCR-RFLP) method the gene and genotype frequencies of PRL gene in native East Anatolian Red (EAR) cattle, which are raised as a genetic resource in Turkey. PCR-RFLP analysis involved the use of the RsaI restriction enzyme. Three patterns of fragments were obtained. The AA, AG, and GG genotype frequencies were 0.07, 0.34, and 0.59 in the cattle population, respectively. For Prolactin-Rsa/ (PRL-Rsa/) polymorphism, the population was in Hardy-Weinberg equilibrium. Heterozygosity was found at a medium rate as 0.338 and the calculated F IS value was 0.072. <![CDATA[<b>Effects of feeding cassava pulp fermented with Acremonium charticola on growth performance, nutrient digestibility and meat quality of broiler chicks</b>]]> Cassava pulp is an energy-rich by-product of the tapioca industry, and is known as a good media for growing filamentous fungi. It may therefore be not only an alternative to maize in poultry diets, but also a carrier for beneficial fungi. This study aimed to investigate the effects of dietary inclusion of the fungus Acremonium charticola (grown in A. charticola-fermented cassava pulp) (AC-FCP), with or without antibiotic growth promoters (AGPs), on growth performance, nutrient digestibility, and meat quality of broiler chicks. A total of 192 broiler chicks were assigned to one of four dietary treatments, including a control diet (maize-soybean-meal-based diet), control diet + AGPs (neomycin) (0.0003% of diet), AC-FCP diet (containing 16% of AC-FCP), and AC-FCP + AGPs. There was a tendency towards lower feed costs per kilogram live bodyweight (BW) gain in AC-FCP and AC-FCP + AGPs than in the control and control + AGPs birds. The birds fed the AC-FCP diet had greater spleen relative weight than the control and AC-FCP + AGPs birds. The birds fed diets containing AC-FCP and AC-FCP + AGPs had heavier ileum and caecum, and tended to have smaller livers than the control and control + AGPs birds. The 2,2-diphenyl-1-picrylhydrazyl (DPPH) percentage inhibition values were lowest and highest in the AC-FCP and control birds, respectively. The breast meat of the control birds had lower crude protein content than that of other experimental groups. In conclusion, dietary inclusion of AC-FCP reduced the feed cost per kilogram live weight gain of broiler chicks. The fungus A. charticola (grown in AC-FCP) seems to play an important role in increasing the relative weight of spleen, ileum and caecum, alleviating oxidative stress, and increasing the protein content of breast muscle of broiler chicks. <![CDATA[<b>Oestrus synchronization with fixed-time artificial insemination in smallholder pig production systems in north-east India: Success rate and benefits</b>]]> Pig production is an important component of the farming systems that are practised in the northeastern region of India and it has special significance for improving the socio-economic status of tribal farmers in the region. In an effort to optimize the production efficiency of rural pig production systems, the potential influence of oestrus synchronization and fixed-time artificial insemination (AI) on synchronizing husbandry programmes was investigated. A total of 117 crossbred sows, selected from various village production units, were randomly allocated to two (control and treatment) groups. The sows in the treatment group (n = 81) received 800 IU of equine chorionic gonadotropin (eCG), followed by 500 IU of human chorionic gonadotropin (hCG) 72 hours after the eCG injection. The sows in the control group (n = 36) served as the untreated control. The onset of oestrus, oestrus signs, oestrus intensity, and duration of oestrus were observed after treatment. The oestrus sows were inseminated twice at 24 h and 36 h, respectively, after hCG injection at various village production units. Results revealed that 86.4% of sows in the treatment group exhibited all the behavioural and physical signs of oestrus. The average interval between treatment and onset of oestrus was 84.8 + 2.43 hours. The mean oestrus intensity of sows in the treatment group was 2.3 (when assessed on a scale of 1 to 3), which did not differ significantly from the oestrus intensity exhibited by the control group. The duration of oestrus varied from 36 to 56 hours in the treated sows, which was significantly longer when compared with the duration of oestrus in the control group. The study obtained a farrowing rate of 82.6% and litter size of 9.2 + 0.32 after oestrus synchronization with timed insemination. Oestrus synchronization facilitated the insemination of a batch of sows at particular locations covering two to three village clusters, which drastically reduced the transport costs for the semen. Oestrus synchronization facilitated the effective implementation of AI by coordinating the insemination of batches of sows, thus reducing shipping and insemination costs. Improving heat detection contributed to shortening the weaning to oestrous interval in smallholder pig production system, which in turn decreased production costs. <![CDATA[<b>Modelling functional and structural impact of non-synonymous single nucleotide polymorphisms of the DQA1 gene of three Nigerian goat breeds</b>]]> The DQA1 gene is a member of the highly polymorphic MHC class II locus that is responsible for the differences among individuals in immune response to infectious agents. In this study, the authors performed a comprehensive computational analysis of the functional and structural impact of non-synonymous or amino acid-changing single nucleotide polymorphisms (SNPs) (nsSNPs) that are deleterious to the DQA1 protein in Nigerian goats. A 310-bp fragment of exon 2 of the DQA1 gene was amplified and sequenced in 27 unrelated animals that are representative of three major Nigerian goat breeds (nine each of West African Dwarf, Red Sokoto, and Sahel of both sexes) using genomic DNA. Forty-two nsSNPs were identified from the alignment of the deduced amino acid sequences. Based on the PANTHER, PROVEAN and PolyPhen-2 algorithms, there was consensus in identifying the mutants I26D, E114V and V115F as being deleterious. Further, differences between the native and the mutant proteins in the subsequent molecular trajectory analysis (stabilizing and flexible residue composition, total grid energy, solvation energy, coulombic energy, solvent accessibility, and protein-protein interaction properties) revealed E114V and V115F to be highly deleterious. Combined mutational analysis comparing the amutant (I26D, E114V and V115F mutations collectively) with the native protein also showed changes that could affect protein function and structure. Further wet-lab confirmatory analysis in a pathological association study involving a larger population of goats is required at the DQA1 locus. This would lay a sound foundation for breeding disease-resistant individuals in the future. <![CDATA[<b>Effect of age on production characteristics of Boschveld indigenous chickens of South Africa reared intensively</b>]]> The Boschveld indigenous chicken is a breed that was developed in South Africa for rural household free-range production of meat and eggs. A performance test was carried out to identify their production characteristics when reared intensively, and to estimate the responses of the production characteristics to age, based on optimization functions. Day-old chicks were procured from the breeder and reared to point of lay, with 1432 layers generating the data. Parameters include egg weight (g), egg number, hen day egg production (HDEP) (%), feed intake (g/b/d), bodyweight (kg), bodyweight gain (g), feed conversion ratio (FCR), feed efficiency (FE), and mortality from start of lay until 44 weeks old. There was a significant effect of age on all these production parameters, except for FCR, which was not affected significantly by age as the birds grew. On fitting a prediction and optimization function using a regression model, these parameters showed significant linear response to age: HDEP, feed intake (g), and bodyweight (kg), while significant quadratic responses were found in egg weight and FCR. The prediction model shows that at age 34, 52 and 65 weeks of lay, bodyweight, HDEP and feed intake respectively, would be optimized, while at age 36 and 43 weeks, FCR and egg weight respectively, would be optimized. This implies that Boschveld indigenous chicken production characteristics can be targeted at the appropriate age and can be optimized, given the age of lay that the birds are in. <![CDATA[<b>Effect of supplementing or treating Eragrostis curvula hay with urea or nitrate on its digestibility and in vitro fermentation</b>]]> The potential of dietary nitrate to reduce enteric methane, apart from it being a source of rumen-degradable nitrogen, has stimulated further research into its use. However, not much has been reported on its suitability in feed treatment. The objective of this study was to determine the effects of urea or nitrate and two methods of non-protein nitrogen (NPN) application (anaerobic pre-treatment versus direct supplementation) to Eragrostis curvula hay, on its in vitro fermentation. An iso-nitrogenous level of NPN (7 g nitrogen/kg feed dry matter (DM)) from either urea or calcium nitrate was used to pre-treat hay by subjecting it to 30 days' anaerobic storage in airtight bottles, or by direct supplementation; each diet having three replicates. Hay samples were dried, milled, and evaluated for in vitro organic matter digestibility (IVOMD), and in vitro gas and methane production, while rumen fluid was analysed for pH, ammonia nitrogen and volatile fatty acids (VFAs). Compared with the untreated hay (control), under both methods of application NPN generally did not increase 48-hour gas production, but did increase the IVOMD of E. curvula hay. However, pre-treatment of E. curvula hay improved IVOMD more than supplementation. Urea inclusion enhanced digestibility more than nitrate, and the urea pre-treatment was more effective than supplementation. In contrast, nitrate inclusion significantly reduced methane production compared with urea and the control, and supplementation of nitrate was more effective in reducing methane than pre-treatment with nitrate. Pre-treatment with nitrate as supplementation increased digestibility and reduced enteric methane emission, indicating the potential of using nitrate as a hydrolytic agent in feed treatment. <![CDATA[<b>Effect of lavender (Lavandula Stoechas) essential oil on growth performance, carcass characteristics, meat quality and antioxidant status of broilers</b>]]> The study evaluated the effect of essential oils from lavender (Lavandula stoaches) (LEO), on growth performance, carcass quality and antioxidant status of broilers. Three nutritionally adequate diets were composed with the addition of LEO at 0, 24, and 48 mg/kg of feed. The diets were fed as mash in the starter (d 0-21) and grower (d 22-39) phases. A total of 405 day-old chicks (Ross-308) were allocated to the three dietary treatments, each with three replicate pens with 45 birds per pen. After the first 21-day feeding period, the bodyweight of chicks fed 24 mg/kg LEO was higher (P <0.01) than the 48 mg/kg LEO treatment, but only slightly higher than that of the untreated group. Diets with 24 and 48 mg/kg of LEO tended to increase final bodyweight of birds at 39 days old. No differences were observed for feed intake (FI), feed conversion ratio (FCR) and mortality among treatments. Feeding chickens on a diet with added LEO significantly reduced the relative weight of liver (P <0.01) compared with the control (CNT) group. Percentage of spleen weight of birds fed 24 mg/kg LEO was lower (P <0.05) than for those who received 48 mg/kg LEO. However, it was similar to that of the CNT. Birds fed diets supplemented with 24 and 48 mg/kg LEO had breast meat with higher brightness (L* value) and higher concentration of superoxide dismutase (SOD) compared with birds that did not receive LEO. Based on the data, it can be concluded that LEO could be used as a growth promoter in broiler nutrition with potential improvements in breast meat quality. <![CDATA[<b>Investigation into the effect of season on oestrus in gilts over two years of climate adaptation</b>]]> This study examined the changes in age at first oestrus, the weaning-to-oestrus interval (WEI), and duration of oestrus (DE) in a Yorkshire sow population during two years of adaptation from a northern (55°48'N, 9°13'W) European region to a southern (44°03'N, 23°35'W) one. The adaptation process induced a grouping effect of gilts around the mean age of the onset of puberty. Autumn and spring were characterized by the most enhanced gilt grouping effect at 201 to 210 days of age. The same effect was found for oestrus duration, which declined from a 12- to 96-hour range in the first year to an 18- to 90-hour range in the second year. The mean age of first oestrus was 0.8 days significantly lower in the second year compared with the first; the maximal lowering (1.7 days) occurred in the winter season. The WEI decreased significantly from the first to the second year in all four seasons, by a mean annual value of 0.88 days (15.9%). DE increased by 6.5 hours (significantly for all seasons) from the first year to the next. DE showed an ascending evolution from winter to spring and descending from summer to autumn, during each monitored year. Adaptation influences the oestrus in sows. The age to puberty and WEI tended to decrease, while DE tended to increase, with a simultaneous decrease in the variability of these oestrus parameters. <![CDATA[<b>Effects of initial fattening age on carcass characteristics and meat quality in Simmental bulls imported from Austria to Turkey</b>]]> The aim of this study was to determine the effects of initial fattening age on carcass and meat quality of Simmental bulls imported from Austria to Turkey. These animals were allocated to two initial ages of fattening groups, namely young (n = 74) and old group (n = 61) at 5.5 and 7.5 months old, respectively. After reaching the target final weights, the animals were slaughtered and the carcass characteristics, area and circumference of the longissimus thoracis et lumborum (LTL) muscle, marbling score, and meat quality, including cooking loss, water-holding capacity (WHC), shear force (WBSF), and colour parameters were evaluated in six animals per group. A comparison of hot and cold carcass weights and dressing percentages, LTL circumference, fat thickness values and marbling score indicated no significant differences between young and old groups. However, the LTL area was significantly affected by the initial age. There were no significant differences between groups in WHC, cooking loss, and WBSF values and meat colour parameters. The results of this study showed that the initial fattening age of bulls showed no significant effect on carcass and meat quality parameters, except the LTL area. The LTL area was significantly higher in young group than the old group. Further studies are needed to improve carcass and meat quality of imported Simmental bulls through modifying the initial fattening age. <![CDATA[<b>Evaluation of growth, milk and manure production in Norwegian dairy goats in one highland of Tanzania 30 years after introduction</b>]]> Dairy goats have been imported into Tanzania since the 1960s to improve the milk production of Small East African (SEA) goats through crossbreeding. The SEA goats have poor genetic potential for milk. Although crossbreeding programmes started in the early 1980s, most were abandoned or failed for a number of reasons, including lack of performance records, which were important for the design and management of breeding programmes for dairy goats. This study was designed to evaluate growth, lactation, and manure yield in Norwegian Landrace (NL) goats in one rural community of Tanzania. Growth was evaluated in 211 goats by birth weight (BW), weaning weight (WW), weight at six (W6M) and nine months (W9M), and average daily gain (ADG). Lactation performance involved lactation milk yield (LMY), lactation length (LL), and dry off days in 251 does. Twenty four additional goats were confined to determine manure production and chemical composition in a different on-station study. The general linear model (GLM) of Statistical Analysis System (SAS) was used in data analysis. Averages for BW, WW, and adult weight (W9M) were 3.27 ± 0.04, 12.79 ± 0.09, and 28.33 ± 0.19 kg, respectively. Average LMY of 322 litres, LL 214.5 days and dry off days of 84 were obtained. Animals with >75% NL genetic make-up produced more milk and showed longer LL and higher ADG than those with 50%. For example, BW was 3.38 ± 0.12 kg in 75% NL animals compared with 2.56 ± 0.12 kg in 50%, whereas LMY was 324.09 ± 16.22 and 248.67 ± 16.20, respectively. The amount of manure was 311.8 g and 218 g per day for mature and grower goats, respectively. Nitrogen was the major content, comprising 1.98% of all nutrients in manure. Compared with the early years of introducing NL goats, growth and productivity of milk have increased several fold, indicating that the development of NL goats in Mgeta is positive at the moment. <![CDATA[<b>Sperm DNA damage in relation to lipid peroxidation following freezing-thawing of boar semen</b>]]> This study investigated the relationships between lipid peroxidation (LPO) and sperm DNA damage following freezing-thawing of boar semen in different extenders. The comet assay was used to measure the extent of sperm DNA damage in a cryoprotectant-free extender or in cryoprotectant-based extenders after single and repeated freezing and thawing. As well as an analysis of sperm motion characteristics, mitochondrial function, membrane integrity, and lipid peroxidation (LPO) were assessed simultaneously with the measurements of sperm DNA damage. Consistent positive significant correlations were found between sperm DNA damage and LPO after freezing-thawing. Comet assay measurements showed that cryo-induced sperm DNA damage was more marked in the cryoprotectant-free extender, irrespective of freezing cycle. The frequency of sperm cells with damaged DNA increased with repeated freezing and thawing in the cryoprotectant-based extenders. Except for sperm DNA damage, there were no consistent associations between post-thaw sperm LPO and sperm quality characteristics. It could be suggested that the increased LPO of membrane phospholipids is associated with higher susceptibility of boar spermatozoa to cryo-induced DNA damage. <![CDATA[<b>Palm kernel expeller increases milk fat content when fed to grazing dairy cows</b>]]> Palm kernel expeller (PKE) is a feed by-product that is used by the dairy and beef industries. This study investigated the effect of partially replacing maize with PKE in a dairy concentrate on milk and ruminal fermentation parameters of Jersey cows grazing kikuyu-ryegrass pasture. Seventy-two multiparous cows were blocked according to milk yield, days in milk, and lactation number and randomly allocated within blocks to one of four treatment concentrates: PKE0, PKE10, PKE20, and PKE30, containing 0, 100, 200, and 300 g PKE/kg dry matter (DM), respectively. Eight rumen-cannulated lactating cows were used in a 4 x 4 Latin square design. All cows grazed pasture as one group, and concentrate was fed at 5.4 kg DM/cow per day. Pasture was allocated at 11.1 kg DM/cow per day. Milk yield was lower with PKE30 than PKE0 (14.3 versus 15.6 kg/cow per day, respectively). Feeding PKE20 and PKE30 was associated with a higher milk fat content of 50.6 and 52.9 g/kg, respectively, than that of 46.3 and 49.3 g/kg of cows fed PKE0 and PKE10, respectively. However, feeding PKE30 compromised fibre degradability. Increased milk fat content and sustained milk yield indicated that 200 g PKE/kg DM can partially replace maize in a dairy concentrate, resulting in a possible added economical advantage, which is dependent on the milk payment system. The lack of a significant effect on milk fat yield and the negative linear relationship of milk protein to milk fat ratio, induced by PKE inclusion, may be unfavourable for certain milk payment systems. <![CDATA[<b>Pre-slaughter bodyweight and daily gains in mink are independent of the housing system</b>]]> The research hypothesis assumed that the size of the cage affects bodyweight after weaning and prior to slaughter and, as a consequence, mean daily bodyweight gains in individuals of both sexes. The study was conducted from 2014 to 2015 at one of the private mink farms in Poland. In total, 800 brown mink were used as the object of research (400 animals in a given year). In each year, the animals were divided into two equal-sized groups, in accordance with their housing system. The first group included animals living in single-storey cages and the second group lived in two-storey cages (i.e. cages with an upper level added). The animals were weighed after weaning and before slaughter. Based on these data the mean daily bodyweight gains were calculated. The research hypothesis was rejected. The conclusion of the analysis of variance is the statement that the cage size did not affect either the animals' bodyweight or their mean daily weight gains. The differences in these results, however, were observed in individuals of different sexes. Males were significantly heavier than females and showed higher daily weight gains. High and positive correlation coefficients were also noticed between bodyweight prior to slaughter and mean daily weight gains. <![CDATA[<b>The effect of quercetin on fertility of frozen-thawed ram epididymal spermatozoa</b>]]> The aim of the present study was to evaluate the effects of quercetin as an antioxidant supplement on frozen-thawed ram epididymal sperm quality. Quercetin is a type of flavonoid antioxidant that is found in plants, with the ability to scavenge free radicals. Twenty testicles from mature rams were collected from a nearby slaughterhouse immediately after slaughter. Epididymal spermatozoa were recovered from the caudal of epididymides by injecting Bracket and Oliphant's (BO) medium retrogradely through the ductus deferens and extended with a tris egg-yolk-based extender and supplemented with 0, 5, 10, 15, 20, and 50 μg/mL quercetin. Following equilibration, the straws were frozen, and then plunged into liquid nitrogen. After thawing, optimized concentrations of quercetin were defined based on their viabilities and used to asse ss fertilization and developmental potential. The results showed that the viability of frozen-thawed spermatozoa significantly increased by using 5 and 10 μg/mL quercetin in the freezing extender. However, total and progressive motility of frozen-thawed spermatozoa were not affected by 5 and 10 μg/mL quercetin in comparison with control (0 μg/mL). The mean number of zygote, morula, and blastocyst stage embryos increased significantly by using 5 and 10 μg/mL quercetin compared with other frozen-thawed treatments(P <0.05). However, the blastocyst rate of fresh sperm was significantly higher (P <0.05). In conclusion, to improve the quality of frozen-thawed ram epididymal spermatozoa, 5 and 10 μg/mL quercetin appears to be an attractive option. Further studies are suggested to understand the synergistic effect of quercetin with other antioxidants to improve the ram freezing-thawing process.