The effect of tick infestation on the productivity of cows of three breeds of cattle

The effect of tick infestation of Hereford, Bonsmara and Nguni cows on the weaning masses of their calves in a dipping versus non-dipping situation was investigated. Breed had a major effect on the level of tick infestation, Herefords being most susceptible and Ngunis least. The productivity of Nguni cows, as measured by the weaning masses of their calves was also least affected. The effect of infestation on the productivity of Hereford cows was the greatest and that on the Bonsmara cows was intermediate. It was estimated that each engorged female tick (predominantly Boophilus decoloratus) caused a reduction of 8.9 g, 8.0 g and 8.6 g in the weaning masses of calves from Hereford, Bonsmara and Nguni cows respectively. The effect of infestation on the productivity of the Nguni cows was nevertheless small because a limited number of ticks fed to maturity on this breed due to its natural resistance.     

Grassland fragmentation and its influence on woody plant cover in the southern Great Plains,USA

Context

Woodland and agricultural expansion are major causes of grassland fragmentation. Fire and rainfall play important roles in maintaining grasslands, however, fire activity has been reduced in fragmented landscapes.

Objectives

Quantify the degree to which basic landscape fragmentation metrics could be used as drivers of woody cover potential.

Methods

Woody plant percent cover was calculated between 2004 and 2008 at?>?2000 sites. At each site, we calculated these fragmentation metrics for grassland cover type (classified by the National Land Cover Database); # patches, landscape proportion, edge density, largest patch index, effective mesh size and patch cohesion index within 3 circular areas (10 km², 360 km² and 3600 km²) surrounding the sampling site. A quantile regression was performed to identify which metrics were useful at predicting the 25th, 50th, 75th or 95th quantile of woody cover distribution.

Results

Grassland proportion and edge density were significant predictors of the woody plant potential (75th and 95th quantile). Woody cover potential was positively associated with edge density suggesting that fragmented areas (i.e., areas with high number of edges) maintained higher woody cover, while grassland proportion was negatively associated with woody plant potential.

Conclusion

We propose that in addition to a lack of fire, fragmented landscapes may facilitate further woodland expansion by reducing natural land and restricting grasslands to smaller, less connected patches, which can maintain higher woody cover. Given current trends in woodland expansion, special attention should be given to areas that are found within a fragmented landscape and climatically prone to woodland expansion.

     

Genetic diversity of Afrikaner cattle in southern Africa

The Afrikaner is an indigenous South African breed of “Sanga” type beef cattle along with breeds such as the Drakensberger and Nguni. Six composite breeds have been developed from crosses with the Afrikaner. Additionally, Afrikaner has been the base from which exotic breeds were established in South Africa through backcrossing. The study examined genetic diversity of Afrikaner cattle by genotyping 1257 animals from 27 herds in different geographic areas of South Africa and Namibia using 11 microsatellite markers. Multiple-locus assignment, performed using the Bayesian clustering algorithm of STRUCTURE, revealed three underlying genotypic groups. These groups were not geographically localized. Across herds and markers, the proportion of unbiased heterozygosity ranged from 0.49 to 0.72 averaging 0.57; mean number of alleles per locus ranged from 3.18 to 7.09, averaging 4.81; and allelic richness ranged from 2.35 to 3.38, averaging 2.67. It is concluded that a low inbreeding level of 2.7% and a moderate to high degree of variation still persists within the Afrikaner cattle breed, despite the recent decline in numbers of animals.     

Endometrial nitric oxide synthase activity in mares susceptible or resistant to persistent breeding‐induced endometritis and the effect of a specific iNOS inhibitor in vitro

Emerging research suggests that the nitric oxide system may play a role in persistent breeding‐induced endometritis (PBIE) in the mare. Differences in uterine nitric oxide (NO) levels between mares susceptible or resistant to PBIE and a dose‐dependent inhibitory effect of NO on uterine contractility have been demonstrated. The objectives of this study were to investigate the difference in total nitric oxide synthase (NOS) activity of the endometrium between susceptible and resistant mares and the effect of a specific inducible nitric oxide synthase (iNOS) inhibitor on the endometrial NOS activity in vitro. Six susceptible and six resistant mares were selected based on preset criteria and the results of an intrauterine challenge with killed spermatozoa during oestrus. Endometrial biopsy samples were collected 24 hr post‐challenge and cultured at 37°C for 24 hr in L‐arginine supplemented minimum essential medium with or without a specific iNOS inhibitor (1,400 W dihydrochloride, 1 mM). The medium and the cultured endometrial tissue were collected after 24 hr of culture and assayed for NO and total protein, respectively. Total NO content of the medium, normalized to endometrial tissue wet weight or total protein, was used as a measure of endometrial NOS activity. Non‐parametric tests were applied for statistical analysis. Susceptible mares had significantly greater endometrial NOS activity than resistant mares. The iNOS inhibitor treatment significantly reduced NOS activity in endometrial samples derived from susceptible and resistant mares. These findings provide a basis for in vivo testing of specific iNOS inhibitors as preventative or therapeutic options for PBIE in mares.     

Changes in biochemical proxy indicators for nutritional stress resilience from Boran and Nguni cows reared in dry arid rangeland

The objective of this study was to determine the changes in biochemical indicators for nutritional stress from a herd of Boran and Nguni cows. A total of 40 cows (20 from each herd) were randomly selected for the study. The animals were identified according to their parities as follows: parity 1 (n = 8), parity 2 (n = 16), parity 3 (n = 8) and parity 4 (n = 8). Serum chemistry levels of glucose, total cholesterol, urea, creatinine, albumin, globulin, aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALP), gamma glutylaminotransferase (GGT), leukocytes, erythrocytes, haemoglobin, packed cell volume (PCV) and platelet counts were determined for 12 consecutive months spanning across the wet and dry seasons. The Boran cows had different creatinine concentration levels at different parities. The Boran cows in parity 1 had the highest (P < 0.05) concentration of creatinine 87.2 ± 5.17 μmol/L than other cows in different parities within the herd. There were significant differences in enzymes such as AST, ALP and ALT among the herd and parities. Boran cows in parity 3 had the lowest (P < 0.05) AST concentration levels of 52.6 ± 3.48 U/L, Nguni cows in parity 4 had the highest concentration of ALP of 161.3 ± 8.10 U/L while Nguni cows in parity 1 had the highest concentration level of ALT 55.1 ± 1.56 U/L than all the cows within the same herd. The Nguni herd had significantly higher (P < 0.05) levels of creatinine in both the wet (97.8 ± 3.27 μmol/L) and dry seasons (108.7 ± 3.29 μmol/L) compared with the Boran herd. Cows from the Nguni herd maintained significantly higher amount of urea, creatinine, albumin and total protein in both the wet and dry seasons as compared with cows from the Boran herd. Cows from the Nguni herd maintained significantly higher amount of urea, creatinine, albumin and total protein in both the wet and dry seasons as compared with those from the Boran herd.     

Biodiversity assessment and conservation strategies

The efficient representation of all species in conservation planning is problematic. Often, species distribution is assessed by dividing the land into a grid; complementary sets of grids, in which each taxon is represented at least once, are then sought. To determine if this approach provides useful surrogate information, species and higher taxon data for South African plants and animals were analyzed. Complementary species sets did not coincide and overlapped little with higher taxon sets. Survey extent and taxonomic knowledge did not affect this overlap. Thus, the assumptions of surrogacy, on which so much conservation planning is based, are not supported.     

The advantages of Ulva (Chlorophyta) as an additive in sea urchin formulated feeds: effects on palatability,consumption and digestibility

The present study was performed to determine whether the palatability, consumption and digestibility of an artificial sea urchin diet could be improved by the addition of a highly preferred seaweed. Four species of macroalgae (Ulva rigida, Ecklonia maxima, Porphyra capensis and Gigartina polycarpa) were assessed by pairwise preference tests. Each macroalgal species was consumed at least once by Tripneustes gratilla and significant preferences always involved Ulva as the most preferred species. Four protein‐rich artificial diets supplemented with varying amounts of Ulva [0, 50, 150 and 200 g kg^?1 designated 0, 5, 15 and 20U, respectively] were then developed and fed to urchins over a 20‐day period. Inclusion of 200 g kg^?1 dried Ulva significantly improved the palatability of the artificial diet and mean dry feed consumption rates were higher in urchins fed the 20U and 15U diets compared with urchins fed diets with a lower Ulva content. Daily digestible protein (DP) intake also differed significantly, with urchins fed the 20U diet having a significantly higher DP intake compared with the 15U, 5U and 0U treatments. These results indicate that inclusion of the palatable seaweed Ulva acted as a feeding stimulant, increasing the acceptability of the diets and boosting protein intake.     

Profile of Penicillium species in the pear supply chain

Postharvest fruit decay caused by Penicillium pathogens is considered to be one of the most important challenges in the pear industry resulting in market‐end losses. Moving export fruit through different environments exposes the product to extensive handling, temperature variations and microbes. Therefore, the profile of Penicillium spp. present in the pear export chain from South Africa (SA) to the UK was studied over a four‐year period. Sampling was done at two packhouse facilities, controlled atmosphere and cold storage areas in SA and at two repack facilities and cold storages as well as a distribution centre and a retailer in the UK. Sampling consisted of swabbing walls and floors and using active and passive air sampling. In total, 5056 isolates were obtained, purified and grouped into 282 morphological groups. Of these, 350 representative isolates were selected for further identification. The five most dominant species in the pear chain were: P. glabrum (23·40%), P. chrysogenum (15·13%), P. crustosum (14·16%), P. brevicompactum (8·96%) and P. expansum (8·39%), of which the latter three were confirmed pathogenic on pears. This study provides a framework to monitor the inoculum potential in environments that fruit move through while being exported.     

Doppler ultrasonographic changes in the canine kidney during normovolaemic anaemia

The haemodynamics of the canine left renal artery (LRA) and interlobar artery (ILA) were evaluated in eleven fasted, healthy, conscious beagles with severe acute (haematocrit [Hct] 16%), moderate chronic (Hct 26%) and mild chronic (Hct 34%) normovolaemic anaemia using Doppler ultrasound. Heart rate, peak systolic velocity (PSV), end diastolic velocity (EDV), time-averaged mean velocity (TAVmean), pulsatility index (PI) and resistive index (RI) were recorded. Doppler values in the dogs following the induction of anaemia states were compared with corresponding values in the same dogs prior to the induction of anaemia. Left renal artery mean PSV, mean PI and mean RI were significantly higher and the mean EDV was significantly lower in severe acute anaemia. No significant change was seen in mean values of the same parameters in moderate or mild chronic anaemia. There was no significant change in TAVmean of the LRA or mean PI and mean RI of the ILA in any grade of anaemia. Acute, severe normovolaemic anaemia significantly altered LRA Doppler parameters in resting dogs without influencing those of the ILA. Moderate or mild chronic anaemia had no effect on any renal Doppler parameter.     

Quantitative differences between the insect faunas of sub-antarctic Marion and Prince Edward islands: A result of human intervention?

The two islands in the sub-Antarctic Prince Edward archipelago are only 22 km apart and are similar in age, geology, physiognomy and climate, yet their insect faunas show both qualitative and quantitative differences. During three visits in 1983 and 1984, the insect fauna of Prince Edward Island was sampled to compare with that of a survey carried out over one year on Marion Island. Two species of weevil (Curculionidae), previously known only from Marion, were recorded on Prince Edward for the first time. The biomass of two major groups of invertebrate decomposers (Lepidoptera and Curculionidae larvae) was significantly higher in heavily manured plant communities on Prince Edward than on Marion. Possible reasons for these quantitative differences are discussed. Although differences in species assemblage play a role, it is concluded that the effects of human influence on Marion Island may be paramount.