Effect of astaxanthin on the quality of boar sperm stored at 17°C,incubated at 37°C or under in vitro conditions

The aim of the study was to investigate the effect of the antioxidant astaxanthin on boar semen. Twenty ejaculates from 10 boars (two ejaculates/boar) were extended and split in three groups: semen control (SC), solvent control (C; semen with dimethyl sulfoxide, the diluent of astaxanthin) and semen with astaxanthin (A) in concentration 0.5 μmol/L. Sperm quality parameters (motility and kinetics, morphology, viability, functional integrity of sperm plasma membrane by Hypo‐Osmotic Swelling Test [HOST] and DNA integrity) were assessed at 0, 24 and 48 hr of storage at 17°C (experiment I), before (0 hr) and after (1 hr) of sperm thermal resistance assay at 37°C (experiment II) and finally before (0 hr) and after (1 hr) sperm in vitro incubation (38.5°C, 5% CO₂, maximum humidity [experiment III]). In experiment I, group A performed overall better than group SC and as a tendency better than group C regarding viability. Total motility, rapid spermatozoa and HOST remained constant across time in group A, whereas they decreased in the remaining groups. In experiment II, regarding motility and viability, group A displayed better results across time than the other two groups. In experiment III, viability and total motility decreased in groups SC and C, while in group A, these parameters were not significantly different between the examination time points. In conclusion, astaxanthin has a beneficial and protective effect on boar semen quality under the investigated conditions.     

A comparison of highveld fodders and fodder flows for growing out long yearling steers

Abstract

A fodder flow/animal experiment 40,8 ha in extent (7,5 ha irrigated), with 19 paddocks, was carried out over a two and a half year period.

The aims were: firstly, to compare fodder crops within seasons, and fodder flows over three seasons (winter‐spring‐summer), by means of pasture and animal parameters; secondly, to make economic comparisons between different fodder flows, for growing out beef steers.

The conclusions were that: Digitaria eriantha ssp. eriantha is superior to Eragrostis curvula cv. Ermelo for animal production; maize residue gives economically favourable results due to low costs and compensatory growth of cattle; an irrigated pasture providing fodder in more than one season of a flow, for example, Festuca foggage — Festuca pasture — Digitaria pasture, gives a very profitable fodder flow, because the costs of production are divided between two seasons; dryland fodder flows with the sequence maize residue — silage or hay — Digitaria or, with silage or hay replacing the maize residue, were also very profitable; and, the fodder flow giving the highest livemass gain per steer, is not necessarily the most economic. Different kinds and classes of livestock require different fodder flows.     

‘n Vergelyking van wei‐ en voergewasse vir die produksie van slaglammers in die Pretoria‐ Witwatersrand‐Vereeniging(PWV)‐gebied

A comparison of pasture and fodder crops for the production of slaughter lambs in the Pretoria‐Witwatersrand‐Vereeniging (PWV) area. A number of pasture and fodder species were evaluated for the production of mutton with weancr lambs. Animal performance and meat production under three stocking rates, which were classified as light, medium, and heavy, were obtained with the aim of identifying best pasture/fodder for every season. The pastures/fodders included were Lolium multiflorum cv. Midmar and Triticum X Secale pastures under irrigation, Avena sativa and Vicia dasycarpa pasture mixture and maize crop residues under rainfed conditions, and Medicago sativa and Digitaria eriantha hay for the winter months. The spring pastures were L. multiflorum cv. Midmar, Lolium perenne cv. Nui and Dactylis glomerata cv. Hera under irrigation, while the summer pastures included Digitaria eriantha var. eriantha and M. sativa cv. Cuf 101 pastures under rainfed conditions and Cynodon dactylon cv. NK37 under irrigation. Of these, the midmar pasture for the winter and spring, maize crop residues for the winter, Hera for the spring and Cuf 101 for the summer seemed to be the best pasture of those tested in their season of use, from an animal production point of view.     

Research note: Level of nitrogen fertilization and the dry matter yield of Digitaria eriantha cv. Irene in the Transvaal middleveld

Abstract

N fertilizer was applied as a single dressing in spring at 0, 20, 40, 80, 160 and 320 kg N ha^‐1 a^‐1 to an established Digitaria eriantha pasture, previously used as a hay crop. The only significant increase in dry matter (DM) yield was obtained with 80 kg ha^‐1 a^‐1. The DM production per unit of nitrogen (N) applied also reached a maximum with 80 kg N ha^‐1 a^‐1. The distribution of rainfall also influenced DM yield.     

Effects of local anaesthesia of 4 to 8 hours duration on the acute cortisol response to scoop dehorning in calves

Objective To determine the effect of a long-acting local anaesthetic on the plasma cortisol response in calves dehorned using a scoop.
Design A physiological study with controls.
Procedure Seventy female calves, 3 to 4 months old, were divided into seven groups and dehorned by scoop with or without a long acting local anaesthetic (bupivacaine) which provides local anaesthesia for 3 to 4 h. In some treatment groups the local anaesthetic was given a second time, after 4 h, to give 8 h of anaesthesia. Blood samples were taken before and for 9 h after treatment and plasma cortisol concentrations were measured.
Results Scoop dehorning caused a marked rise in plasma cortisol concentration, which returned to pre-dehorning values after 7 h. The cortisol concentrations of calves given bupiva-caine were similar to those of control animals for 4 h after dehorning, but then a significant and protracted rise occurred, with concentrations returning to pretreatment values at about 9 h after dehorning. In calves given a second treatment of bupivacaine 4 h after dehorning, the plasma cortisol concentration remained similar to control values for 8 h after dehorning but then increased sharply.
Conclusions During its period of activity long-acting local anaesthetic prevented the rise usually seen after scoop dehorning in plasma cortisol concentrations; by inference it also alleviated the pain-induced distress caused by this procedure. However, when its effects had worn off the plasma cortisol values rose sharply indicating that animals still experienced pain-induced distress despite local anaesthetic being administered.     

Flow Cytometric Chromosomal Sex Sorting of Stallion Spermatozoa Induces Oxidative Stress on Mitochondria and Genomic DNA

To date, the only repeatable method to select spermatozoa for chromosomal sex is the Beltsville sorting technology using flow cytometry. Improvement of this technology in the equine species requires increasing awareness of the modifications that the sorting procedure induces on sperm intactness. Oxidative stress is regarded as the major damaging phenomenon, and increasing evidence regards handling of spermatozoa – including sex sorting – as basic ground for oxidative damage. The aim of this study was to disclose whether the flow cytometric sorting procedure increases the production of reactive oxygen species (ROS), and to identify if ROS production relates to DNA damage in sorted spermatozoa using specific flow cytometry‐based assays. After sorting, oxidative stress increased from 26% to 33% in pre‐ and post‐incubation controls, to 46% after sex sorting (p < 0.05). Proportions of DNA fragmentation index post‐sorting were approximately 10% higher (31.3%); an effect apparently conduced via oxidative DNA damage as revealed by the oxyDNA assay. The probable origin of this increased oxidative stress owes the removal of enough seminal plasma due to the unphysiological sperm extension, alongside a deleterious effect of high pressure on mitochondria during the sorting procedure.     

Evaluation of head-only and head-to-tail electrical stunning of farmed eels (Anguilla anguilla, L.) for the development of a humane slaughter method

The overall objective was to evaluate the suitability of electronarcosis as a stunning method for farmed eels. In the first experiment the minimum electrical current needed to induce a general epileptiform insult by head‐only stunning was assessed. The individual eels (n = 40) with a live weight of 700–800 g were fixed in a specially designed re‐strainer. The EEG (electroencephalogram) and ECG (electrocardiogram) recordings, observation of behaviour and responses to pain stimuli were used to assess unconsciousness, insensibility and cardiac function. The applied current of 150, 200 or 250 V, 50 Hz, AC was delivered via scissor‐model stunning tongs for approximately 1 s. A general epileptiform insult was observed in 31 eels for which a successful EEG recording was obtained, using 255 ± 4 V, 545 ± 32 mA, for 1.2 ± 0.2 s. The general epileptiform insult as measured on the EEG was characterized by a tonic/clonic phase and an exhaustion phase. The behaviour showed one phase: tonic cramps alternated by clonic ones. The heart rate was 22 ± 8 beats min^?1 (n = 23) prior to stunning. After stunning the ECG revealed fibrillation. In the second experiment the behaviour of seven individual eels able to move freely in water was observed after head‐only stunning (250 V). Two phases were distinguished. Limited tonic and clonic cramps combined with backward swimming were followed by heavy clonic cramps combined with unco‐ordinated movements such as jumping out of the water. A distinct exhaustion phase was not observed in all animals. In the third experiment a head‐to‐tail electrical method was examined in 15 eels for rendering the eels unconscious and insensitive prior to slaughter. They were stunned by applying 253 V for 3 s followed by 50 V for 5 min. In the fourth experiment nine eels were head‐only stunned with 260 V for 1 s immediately followed by 50 V for 5 min applied from head to tail. Results obtained in these two experiments were similar. After stunning no brain activity and no responses to pain stimuli on the EEG were observed and the ECG showed ventricular extra systolae. It was observed that it might take 60 ± 25 min or longer for a complete recovery. It can be concluded that for effective electrical stunning of eels with a weight of 700–800 g an average current of 545 ± 32 mA (at approximate 250 V, 50 Hz AC) is needed. In this case, within a confidence level of 95% at least 91% of the eels are effectively stunned (n = 31). Therefore, it is recommended to increase the minimum current for an effective stun in practice to 600 mA. Further research is needed to determine the conditions to induce permanent unconsciousness and insensibility of the eels to protect the animals at slaughter.     

Effect of Mating Frequency on Sow Reproductive Performance under Field Conditions and Natural Mating in Large Outdoor Production Units

The effect of mating frequency on fertility and litter size of sows, kept in outdoor production systems was investigated. Sows that were mated once or twice during a single oestrus were included in the study to compare the effect of number of matings on farrowing rate and litter size. Natural mating was used during the study period. Four groups of sows of parity two or more were either mated once 28–30 h after the onset of oestrus or were mated 28–30 h after the onset of oestrus and again 24 h later. The farrowing rate did not differ significantly between single‐ and double‐mated sows, although a noticeable but non‐significant depression in farrowing rate was evident between the groups of single‐mated and double‐mated animals. With the exception of total‐born litter size (p > 0.05), the total number born and number of live‐born piglets per litter were significantly (p < 0.05) lower in the group of sows that received only one mating compared with the double‐mated animals. The implication of these results is that the double mating by natural service of sows kept in an outdoor production systems may improve litter size.