South African Journal of Animal Science

Factors influencing within-litter variation of birth weight and the incidence of runt piglets

The present study was conducted to investigate factors affecting within-litter variation of piglet birth weight and the incidence of runt piglets. In total, 8433 piglets were included in the study. They had been born from 624 Landrace x Yorkshire sows raised on ten farms in the north of Vietnam. A linear mixed effect model (LMEM) and a generalized linear mixed model (GLMM) were used to determine the associations between the risk factors and within-litter variation in birth weight and number of runt piglets, respectively. The within-litter standard deviation (SD) of birth weight and its coefficient of variation were 0.27 ± 0.10 kg and 19.8 ± 8.0%, respectively. Litter size was positively associated with within-litter variation in birth weight, whereas the mean birth weight was negatively associated with litter size. The incidence of runt piglets (birth weight <1.11 kg) was 21.3%. Increases in litter size and decreases in litter weight were associated with the incidence of runt piglets. Mean and SD of birth weight within litter were the most significant risk factors for runt piglets. The GLMM, which contained the mean and SD of birth weight, explained 36% variation of the incidence of runt piglets. The results of the present study suggested that increased mean birth weight and litter weight would be beneficial approaches for reducing within-litter variation in piglet birth weight and incidence of runt piglets, which may subsequently increase perinatal and preweaning survival.

Partial replacement of maize meal with high-tannin sorghum meal affects finishing and methane emissions of Pedi goats

This study was conducted to determine the effect of replacing maize meal with Sorghum vulgare meal, a high-tannin sorghum meal, in fattening diets on bodyweight and methane emissions by yearling male Pedi goats. A total of 12 yearling male Pedi goats with an average initial liveweight of 14 ± 1 kg were randomly assigned to a complete randomized design with four treatments, which were formulated such that 0%, 10%, 20% and 30% of the maize meal was replaced with Sorghum vulgare meal. The experiment was conducted over 28 days, with 21 days adaptation, followed by seven days for sample collection. Replacing maize meal with sorghum did not produce detectable (P >0.05) effects on bodyweight and live weight gain. The various replacement levels of sorghum meal had no detectable effects on the blood cell profile of Pedi goats either. However, they reduced methane emission and improved feed conversion ratio (P <0.05), which allowed for an approximation of the feed required by growing goats. These findings may assist farmers in selecting and utilizing the right feeds to maximize profitability in the small-stock farming sector.

Effect of dietary energy concentration on the growth of slow-growing Korat chickens from 43 to 84 days old

The aim of this study was to estimate the effect of diets with different energy levels on the growth performance of slow-growing chickens (so-called Korat chicken (KRC)). The KRC is a cross between a male Thai native chicken (Leung Hang Khoa) and females from crosses among modern broiler and layer lines. The study was divided into two experimental periods when the birds were from 43 to 63 days old and 64 to 84 days old. Birds received feed and water ad libitum throughout the trial. In this study, 1200 mixed-sex KRC (624 and 576 chicks in phases 1 and 2, respectively) were distributed equally to four diets, which provided 2750, 2900, 3050 and 3200 kcal ME/kg. There were six replicate pens of each treatment. At both ages, increased energy content of the diet resulted in decreased feed intake (FI) and thus improved the feed conversion ratio (FCR). Weight gain was unaffected by the treatments. Using a broken-line analysis, dietary energy containing about 3200 kcal ME/kg was found to have the most beneficial effect on FCR during both periods. Thus, the optimal ME for KRC between 43 and 84 days old was 3200 kcal/kg.

Evaluation of grass and legume tropical mixtures and performance of grazed sheep

The objective of this research was to determine the pasture structure, nutritional value, animal behaviour, intake, and performance of Santa Inês sheep grazing pastures with various mixtures of grass (Andropogon gayanus) and forage legume (Stylosanthes sp. and Calopogonium mucunoides). A randomized block design was adopted with the treatments arranged in a 3 x 2 factorial scheme, with the factors consisting of cropping systems and grazing cycles. Grass in the mixed species pastures had a greater leaf/stem ratio than in the monoculture. Total forage mass was greater in the mixed pastures, which had the highest concentrations of crude protein and total digestible nutrients, the lowest fibre concentration, and the highest in vitro dry matter digestibility. Legumes were grazed with the highest frequency, and biting rate was highest in Andropogon gayanus with Stylosanthes sp. The highest intake (kg/day) was found in the mixed swards and the highest animal weight gain (143 g/day) in the mixed pastures. The pastures of Andropogon gayanus mixed with Stylosanthes sp. and C. mucunoides showed improved forage nutritive value and intake compared with the grass monoculture.

**Feeding Nigella sativa oil to broilers affects their performance, serum constituents and cecum microbiota**

The objective of this study was to assess the effect of supplementation of Nigella sativa oil (NSO) as a growth promoter in broiler diets. A total of 300 unsexed one-day-old Arbor Acre broiler chicks were randomly divided into five treatment groups (60 chicks/group). Each group was divided into five replicates with 12 chicks per replicate. Group 1 was fed on the basal diet with no additives (control). Group 2 was fed the basal diet supplemented with oxytetracycline (OTC) at the level of 50 ppm. Groups 3, 4 and 5 were fed the basal diet supplemented with 500, 1000 and 1500 ppm NSO, respectively. Birds fed on 1500 ppm NSO diet showed the heaviest body weight at 14, 28 and 42 days of age. Feed conversion ratio was significantly improved at all ages with the inclusions of OTC and NSO generally superior to the control group. The relative weight of spleen was increased significantly by the addition of NSO at various levels. However, relative weights of thymus and bursa were not altered by the treatments. Total bacterial count, total yeast and moulds count, E. coli and salmonella spp. counts were reduced significantly, whereas the total lactic acid bacteria count was increased in OTC and NSO groups compared with control. Nigella sativa oil could be used in broiler chicken feeds as a natural alternative to antibiotic growth promoters to improve gut health and consequently growth performance.

Polymorphism of growth hormone gene and its association with body measurement traits in Boer goat does

The study examined single nucleotide polymorphisms (SNPs) in the growth hormone gene (GH1) in Boer goat does and their relationship with body measurement traits, namely bodyweight, body length, heart girth, rump height, rump width, ear length, cannon circumference, and head width. Seventy-six Boer goat does between the ages of 2 and 4 years were used as experimental animals. Polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP) and deoxyribonucleic acid (DNA) sequencing techniques were used to detect SNPs. Chi-square test was used to measure the genetic equilibrium and a general linear model was used for the marker-trait association analysis. The PCR-RFLP and DNA sequencing results discovered one SNP (G505C) in the exon 5 of the candidate gene with two genotypes observed (AA and AB). The association analysis indicated that bodyweight was associated with the genotypes (P <0.01), but not with any of the morphometric traits. A chi-square analysis indicated that the genotypic frequencies were in Hardy-Weinberg equilibrium. The polymorphism discovered in this study is a putative marker that might assist farmers in improving their does' bodyweight through marker-assisted selection.

Physicochemical and morphometric characterization of eggs from emus (Dromaius novaehollandiae)

There is a dearth of scientific information about the physicochemical characteristics of eggs from ratite birds including emus. Thus, an experiment was carried out with 19 laying emu ((Dromaius novaehollandiae) hens, maintained in cages, and divided into two groups according to age, to record morphometric and physicochemical characteristics of the eggs. The width, length, average weight, form index, Haugh unit, yolk index, percentage of egg components, yolk pigmentation, pH of yolk and albumen, and eggshell weight and thickness were recorded. This morphometric characterization was influenced by the age of the hen. Neither the yolk nor albumen pH was influenced by the age of the bird. The eggs from emus that were raised in captivity presented physical and morphometric characteristics that varied with age, although they remained within the ranges of observations that were previously observed for ratite species, but were different from those of domestic chickens. The high fragility and easy rupture of the vitelline membrane in the emu eggs may limit the use of this product in industrial applications. Further studies of emu eggs are needed to improve their suitability for consumption and for the food industry.

Effects of breed and fattening system on fatty acid and chemical composition of meat from male lambs

The purpose of this study was to examine the fatty acid and chemical composition of the Longissimus dorsi (LD) from male Tuj and Hemsin lambs reared in extensive, semi-intensive and intensive feeding systems. At the end of 90 days eight lambs from each breed and feeding system were slaughtered to determine chemical composition, and six lambs in each group were selected at random to assess fatty acid composition. Breed and feeding system interaction affected the quantities of saturated fatty acids (SFA), monounsaturated fatty acids (MUFA), and polyunsaturated fatty acids (PUFA), and the atherogenic (AI), thrombogenic (TI), and nutritive value (NVI) indices. In Hemsin the ratio of PUFA to SFA was higher in lambs fed in the extensive system than those produced in the semi-intensive and intensive systems, which were similar, whereas in Tuj this ratio decreased from the extensive to semi-intensive to intensive feeding systems. The ratio of omega n-6 to omega n-3 fatty acids was lower in the extensive and semi-intensive systems than it was in intensively fed Hemsin lambs, but increased with the intensity of feeding in Tuj lambs. Intramuscular fat content was higher in Hemsin lambs than in Tuj lambs and increased with the intensity of the feeding system. Conjugated linoleic acid content (CLA) was affected by feeding system in Hemsin lambs, but not in Tuj lambs. Because of their high PUFA/SFA ratio and low TI value, Tuj lambs reared in extensive feeding system were deemed to have the best performance.

The impact of dietary protein content and lighting programme on breast meat yield in broiler chickens

Effects of the interaction between lighting programme and dietary protein content on broiler performance and meat yield were investigated. The hypothesis was that low breast meat yield from birds managed under short day lengths could be improved by increasing dietary protein content. The treatments consisted of four lighting programmes and four dietary protein levels. They were applied to sexed broilers from one day old to 35 days old. Eight light-tight rooms each contained eight pens with 50 birds, sexes separate, in each pen. Each feed x sex treatment was replicated twice in each room, with the four lighting treatments also being replicated twice. Multiple regression analysis was used to measure responses to the three factors. There was no significant interaction between dietary protein content and lighting programme in feed intake, feed conversion efficiency, bodyweight gain, carcass chemical composition and breast meat yield. Breast meat yield was linearly related to the number of hours of light, the highest yield occurring on the longest day length. Food intake was the same on the shortest day length and the longest, yet breast meat yield was greater on the 23-hour light programme. The decreased breast meat yield in broilers given short day lengths was therefore not the consequence of a shortage of dietary protein, and this hypothesis therefore had to be rejected.

Quality of ram semen cryopreserved in egg yolk extender supplemented with myricetin

The aim of this study was to evaluate the ability of the antioxidant myricetin to protect ovine spermatozoa during freezing-thawing. Five semen pools, obtained from four rams, were diluted and frozen in Tris-egg yolk extender (5% glycerol) supplemented with myricetin at 0, 20, 30, 40, 100, 200, 300, and 400 nM. After thawing at 37 °C for 30 seconds and incubation (37 °C) for two hours, these variables were measured: kinematics, plasma and acrosome membrane integrity, mitochondrial membrane potential, intracellular reactive oxygen species (ROS) levels, lipid peroxidation and membrane stability. There was no interaction between treatment and time, and no direct effect of treatments for the kinematics parameters (P >0.09; P >0.2113, respectively) and flow cytometry (P >0.41; P > 0.52, respectively). The means of progressive motility, curvilinear velocity, straight-line velocity, average path velocity, linearity, amplitude of lateral head displacement, percentage of intact plasma membrane and acrosome membrane, oxidative stress and membrane stability were reduced during incubation (P <0.04), whereas the cross-beat frequency increased (P =0.0001) throughout incubation. Thus, the addition of myricetin to the semen extender does not produce an antioxidant effect on ram semen in vitro.

Effects of flushing and various doses of β-Carotene and vitamin E applications on the reproductive performance of ewes

The aim of this study was to determine whether fertility could be enhanced in Kivircik ewes during the anoestrous period by flushing or by administering an injectable (Ovostim) containing β-Carotene and vitamin E. Three-year-old Kivircik ewes (n = 99) were used. The ewes were randomly divided into four groups: flushing, a single dose of Ovostim (5 ml/ewe) before the breeding season, a dose of Ovostim 10 days before the breeding season and a second dose at its start, and an untreated control. Results showed that pregnancy rate was higher in the treated groups than in the control (P <0.001). The single dose of Ovostim produced more multiple births (72%) and the highest litter size (1.64) compared with the other treatments. Although the double-dose of Ovostim influenced the ewes in the anoestrous period to the point of becoming pregnant, it failed to favourably affect the number of lambs born per ewe lambing. In conclusion, flushing the ewes or administering a single dose of Ovostim was shown to be advantageous in comparison with untreated ewes or those given two doses of Ovostim.

Bone, microbiological and intestinal characteristics of piglets fed diets containing Lithothamnium calcareum

The aim of this study was to assess the effect of calcitic seaweed (CS), calcitic limestone (CL) and monodicalcium phosphate (DP) fed to piglets in various combinations on their gastrointestinal tract and bones. A total of 128 piglets (21 days old, 5.50 ± 0.49 kg bodyweight (BW) were assigned to treatments in a randomized complete block design and eight replications to one of four diets: D1: with CL + DP, D2: with CL, CS + DP, D3, similar to D2, but with 30% less calcium from CS and DP, and D4: with CS + DP. Treatments affected the metatarsal bones, mineral concentration in the heart and liver, and pH in the cecum and colon. Piglets fed D4 tended to have a greater Enterobacteriaceae count in the jejunum and ileum compared with D1 (4.82 vs 4.79 CFU/g). Piglets fed D1 and D3 had a greater Enterobacteriaceae count in their cecum than D4 (4.79 and 4.80 vs 4.76). The D2 and D1 treatments produced greater crypt depth (CD) in the duodenum and ileum compared with D3 and D4, respectively. Feeding D3 resulted in a greater villus height (VH) to CD ratio in the duodenum compared with D2 and showed a 24.5% increase in heart weight compared with fed D1. In conclusion, CS could be an alternative source of calcium source for piglets. The inconsistent findings of the present study suggest the need for further studies to better understand the interplay of effects of Ca + source and level on its metabolism.

Gene expression at different cell stages of in wfro-fertilized bovine embryos

The birth rate of embryos produced in vitro (IVF) is still lower than that of embryos produced in vivo. Three major steps for the success of the IVF technique are maturation of immature oocytes, fertilization of matured oocytes, and culture of the resulting embryos. Studying mRNA expression in early embryonic development stages is important and can help to assess embryo quality and optimize production protocols in vitro. The current study aimed to determine the expression levels of developmentally important genes in different stages of bovine embryos produced in vitro. Cumulus-oocyte complexes (COCs) were collected from bovine ovaries and cultured in synthetic oviduct fluid (SOF) medium for 7 - 9 days. Embryos were collected at the time-points listed above, and mRNA expression of genes involved in pluripotency (OCT4), DNA methylation (DNMT1), apoptosis (BAX), and metabolism (GLUT1) and a heat shock protein (HSP70) was estimated from the 2-cell stage to the blastocyst stage of embryos. The results showed statistically significant differences in the relative abundance (RA) of OCT4, DNMT1, BAX, and GLUT1 gene transcripts among the different stages, whereas there were non-significant differences in the RA of HSP70 between these stages. In conclusion, gene expression levels differ among the developmental stages of embryos produced in vitro, possibly because of the timing of embryonic genome activation (EGA).

**Prevalence and economic significance of Hypoderma bovis in Ardahan**

The aim of this study was to determine the prevalence of cattle infected by Hypoderma, a parasite that causes great economic losses in the world, especially in the Ardahan region. A total of 31 095 cattle skins were randomly selected between 15 November 2020 and 15 March 2021 and examined. The prevalence of warbles was 47.3%. The proportions of cattle with warbles on the skin on their backs were 76.6% in one-year-old and younger animals, 60.9% in two- and three-year-old animals, and 16.5% in cattle that were four years old or more. It was determined that 53.6% of the cattle with warbles on the back skin were indigenous breeds, 47.6% were Simmental and Montofon crosses, and 36.2% were domestic breeds. The average number of larvae was 8.2. Interviews with the owners of the infected animals revealed that hide loss was on average 10% in liveweight, with a 5% to 8% in the milk production of dairy cows. In the animals under investigation the total economic loss from warbles caused by damage to the hide was calculated as US$114 188. Thus, it is important to carry out preventive practices regularly to limit the spread of the parasite and prevent economic loss in Ardahan.