Diurnal thermoregulatory responses in pregnant Yankasa ewes to the dry season in a tropical Savannah

The study investigated concomitant effect of gestation and high ambient temperature under a tropical environment on rectal temperature (RT), respiratory rate (RR) and heart rate (HR) responses in Yankasa ewes. Twenty Yankasa ewes, consisting of ten pregnant and ten non-pregnant ewes, were used for the study. Ewes were synchronised and bred, such that each gestation phase coincided with different periods of the dry-seasons, early-gestation (cold/harmattan), mid-gestation (peak hot-dry) and late-gestation (late hot-dry). The RT, RR and HR were recorded thrice, 2 days apart at middle of each gestation period at 06:00, 14:00 and 18:00 h, concurrently with dry- (DBT) and wet-bulb temperatures of the experimental pen. The DBT was positively correlated with RT, RR during the different gestation stages. The RT significantly (P < 0.001) increased with the hour of day, regardless of the physiological status of the ewes, with peak at 14:00 h. Values of RT and RR were higher (P < 0.05) in pregnant than non-pregnant ewes at mid- and late-gestation, respectively. Mean RT was lower (P < 0.001) at 06:00 h in pregnant than non-pregnant ewes at early-gestation (cold-dry). The HR was (P < 0.05) higher in pregnant than non-pregnant ewes during the different gestation phases. In conclusion, ambient temperature and gestation concomitantly modulate diurnal thermoregulatory responses of the ewes to hot-dry season. Adequate measures should be adopted to mitigate adverse impact of prolonged high RR on the dam and the foetus during the peak of ambient temperature prevailing in the tropical Savannah environment.     

Anatomical and surface ultrastructural investigation of the tongue in the straw-coloured fruit bat (Eidolon helvum,Kerr 1972)

The morphology of tongue in straw-coloured fruit bat from tropical forests was evaluated in relation to frugivorous diets and in comparison with other species that consumes other food types. Gross, stereomicroscopy, scanning electron microscope and histological methods were used. The tongue was relatively long with round tip, which closely fitted into oral cavity. Five types of mechanical papillae included crown-like and trifid filiform papillae. Also bulky, cone-shaped papillae and long conical papillae were identified. These mechanical types also showed variations in shape, size and number of processes of papillae. Transitional forms of these mechanical papillae were present. Fungiform papillae with taste pores were interposed amongst filiform types in apex and body; three ovoid-shaped vallate papillae were in triangular arrangement on root and displayed taste pores. Some bulky, cone-shaped papillae surrounded the vallate papillae. Histologically, mechanical filiform types showed highly keratinized stratified squamous epithelium and dense connective tissue core with secondary papillae. Taste buds appeared in fungiform and vallate papillae. Neutral and acidic secretions were identified in lingual glands of root. The presence of prominent filamentous processes of filiform papillae and conical papillae of the tongue in conjunction with gustatory papillae ensures adaptation to copious fruit diets. The gross morphometric and histometric parameters of the tongue did not differ remarkably from previous values obtained for some fruit bats with comparable weight. This investigation showed similarities with fruit bats such as large flying fox and Egyptian fruit bat and reflect common diet and feeding habits but varied from insectivorous and nectivorous bats.     

Optimal management of nitrogen fertilizer in the main rice crop and its carrying-over effect on ratoon rice under mechanized cultivation in Southeast China

This study attempted to clarify the carrying-over effect of different nitrogen treatments applied to the main crop on the crop population growth and yield formation of ratoon rice under mechanized cultivation in Southeast China.  Based on the constant total nitrogen application amounts (225.00 kg ha^–1) in the main crop, an experiment with different ratios of basal and topdressing nitrogen fertilizer (the ratio of basal fertilizer:primary tillering fertilizer:secondary tillering fertilizer:booting fertilizer at 3:1:2:4 (N1), 3:2:1:4 (N2), 3:3:0:4 (N3), and 4:3:0:3 (N4), respectively, and a control without nitrogen treatment (N0)) was set up across two consecutive years in field using hybrid rice variety Yongyou 1540 as the test materials.  The results showed that the total tiller number and effective tillering percentage increased in the main crop under the N1 treatment, more nitrogen fertilizer applied in late growth stage of the main crop, and its effective tillering percentage of the main crop was the highest at up to 70.18%, which was 9.15% higher than that of conventional fertilization treatment (N4), more nitrogen fertilizer applied in early growth stage of the main crop.  The same tendency was observed in leaf area index (LAI) value of the main crop and its subsequent ratoon rice, which were 16.52 and 29.87% higher, respectively, in the N1 treatment than that in the N4 treatment at the full heading stage.  The same was true in the case of the transport rates of stem and sheath dry mater and the canopy light interception rates in both the main and its ratoon crops.  The transport rate of stem and sheath in main crop rice under N1 treatment increased by 50.57% compared with N4 treatment.  The canopy light interception rate of N1 treatment increased by 5.07% compared with N4 treatment at the full heading stage of the ratoon crop.  Therefore, the total actual yield was the highest in the main and its ratoon crops under N1 treatment, averaging 17 351.23 kg ha^–1 in two-year trials, which was 23.00% higher than that in the conventional fertilization treatment (N4).  The results showed that appropriate nitrogen treatment was able to produce a good crop stand in the main crop, which was essential for producing a good ratoon crop population and high yield especially under mechanized cultivation with low stubble height of the main crop.  The study suggested that shifting the proper nitrogen application amounts to the late growth stage of the main crop, such as N1 treatment, not only had a higher productive effect on ensuring the yield of the main crop, but also had a positive effect on the axillary bud sprouts from the stubbles for ratoon rice, resulting in an increased percentage of productive panicles and achieving the goal of one planting with two good harvests under the conditions of our study.     

Effects of a controlled-release albendazole capsule on parasitism and production from grazing Merino ewes and lambs

SUMMARY: Effects of a controlled-release albendazole capsule (CRC) on nematode parasitism and production of Merino ewes and lambs were Investigated in a replicated grazing experiment between August 1986 and July 1989. The experiment was conducted on a site where the naturally occurring parasites were benzimidazole-resistant, with double the recommended dose of oxfendazole reducing faecal egg counts of Trichostrongylus colubriformis by less than 50%. Two CRC treatments were compared with a minimal treatment control and the widely-used strategic control program, Wormkill.
Egg counts and worm burdens of major parasite species of ewes and of lambs before and after weaning were significantly reduced by use of the CRC in ewes before lambing or in lambs at weaning. These parasitological effects were reflected in increased productivity of CRC ewes and lambs. Ewes given CRCs lost less weight and grew more wool during lactation than ewes given Wormkill or control treatments, while their lambs gained more weight and had heavier fleeces than lambs from Wormkill or control treatments. Where lambs were weaned by removing ewes from the lambing paddock, administration of the CRC at weaning to lambs whose dams had also been treated with the CRC did not result in improved production when compared with lambs from ewes dosed with CRCs and treated after weaning according to the Wormkill program. Some possible uses for the CRC in ewes and lambs were identified.     

Effect of Ram Age on Structural and Functional Competence of Frozen–Thawed Spermatozoa in Dairy Sheep

The objectives of this study were to investigate the influence of ram age on structural and functional competence of frozen–thawed spermatozoa and to test the hypothesis that increasing number of sperm bound to the zona pellucida in vitro was associated with decreasing in vivo fertility of frozen semen. Rams were allocated into two groups. Each group consisted of five rams aged either 1–2 years (young) or 4–5 years (mature). Three successive ejaculates were collected from each ram using an artificial vagina. Only ejaculates of ≥ 2.5 × 10⁹ sperm/ml and 80% sperm progressive motility were pooled per ram, diluted with Bioxcell^® medium and frozen in 0.25 ml straws. The end points of post‐thawing semen evaluation were computer‐assisted cell motility analysis, sperm capacitation (chlortetracycline assay), simultaneous assessment of plasma membrane integrity, mitochondrial membrane potential and condensation status of nucleus, per‐cell analysis of lipid peroxidation using C11‐BODIPY^581/591, sperm‐hemizona binding (HZB) ability and sperm fertility after laparoscopic insemination of ewes (n = 114) in the progestagen‐synchronized oestrus. The results showed that mature rams had significantly lower values of sperm hyperactivated motility and peroxidized sperm, higher percentages of live non‐capacitated sperm and sperm cells with intact plasma membrane, functional mitochondria and condensed chromatin, as well as, greater lambing rate and ewe prolificacy. Sperm HZB binding ability was higher (p < 0.05) for young than for mature rams. Significant correlations were found between number of spermatozoa bound to the zona pellucida and semen fertility (r = ?0.63 to ?0.71). In conclusion, mature rams have better semen quality and in vivo fertility than young rams. Cryocapacitation can be involved in decreasing ram semen fertility as evidenced by the high number of spermatozoa bound to the zona pellucida in vitro.     

Maintenance of acquired immunity to Trichostrongylus colubriformis in Merino sheep that are losing weight

SUMMARY The effect of loss of weight on maintenance of acquired immunity to Trichostrongylus colubriformis in Merino sheep was assessed in 2 experiments. Adult Merino sheep with previously acquired immunity to T colubriformis were housed in individual pens. Sheep were infected 3 times weekly with 2000 T colubriformis larvae. A diet based on chopped oaten and lucerne hay (experiment 1) or a pelleted diet based on lucerne hay and grain products (experiment 2), was offered in amounts to sustain a moderate gain in body weight, or was reduced step-wise to cause a loss in body weight. Worm egg counts were determined weekly. The reduction in feed on offer resulted in a mean weight loss of 4.0 kg over 9 weeks (experiment 1) or 4.8 kg over 7 weeks (experiment 2). Based on worm egg counts, there was no indication of a change in immunity to T colubriformis in either of the experiments. These results suggest that acquired immunity to T colubriformis in adult sheep that are exposed to infection is maintained during periods of moderate loss of weight associated with inadequate nutrition.