Culicoides spp. (Diptera: Ceratopogonidae) Associated with Farmed Ostriches (Struthio camelus) in Botswana

Veterinary Research Communications -     

Emerging technologies for identifying superior dairy cows in New Zealand

The performance of animals is determined by the interaction of their genes with environmental circumstances. Accordingly, animals exhibiting superior performance are not necessarily the animals with the best genes nor are they the best choice of parents. Statistical analyses of production records for repeated traits, e.g. lactation yields and reproductive performance, show that part of the variation in performance among animals in the same herd and year is due to genetic differences, and the remainder is due to so-called residual or environmental factors that are not passed on to offspring. These within-herd environmental factors can be partitioned into a component that affects performance throughout an animal's lifetime, and a part that is unique to each observation. The process of animal evaluation from pedigree and performance records partitions the superiority of each cow into these three components. Reliable assessment of the genetic merit of bulls has required progeny testing, and for cows has required observation of their own individual performance. Selection on the genetic or breeding value component has systematically improved animal performance over recent decades, but has been limited by the age at which assessments of genetic merit are available.

Emerging molecular technologies can read DNA sequences or measure RNA expression and have allowed the identification of a number of chromosome regions, and a few specific genes in those regions, that influence economic performance. This information allows better characterisation of the relationships between animals and more accurate predictions of genetic merit in bulls without progeny information and in cows that have yet to produce their own performance record. At some stage, enough genes responsible for variation in performance will be identified to allow faster genetic progress through selection of animals at young ages and therefore more rapid turnover of the generations. Mechanisms that modify gene expression have been identified and these may ultimately allow animals to be selected at an early age for lifetime productivity, accounting for processes that modify gene expression and lead to differences in performance that are not reflected by DNA sequence information. This review describes the status of these emerging technologies and their likely role in the improvement of dairy cattle.     

Diseases of indigenous chickens in Bokaa village, Kgatleng district, Botswana

This study examined flock size and management, level of internal and external parasite burden and seroprevalence of antibodies to poultry pathogens in indigenous chickens in Bokaa village, Kgatleng district, Botswana. The mean flock size was 22.6 +/- 6.85 with a range of 11-34. The mean body weights of cocks and hens were 2.28 +/- 0.56 kg and 1.70 +/- 0.38 kg, respectively. Housing and commercial poultry feed were not provided. Ascaridia galli, Heterakis gallinarum and Syngamus trachea were found in some birds. Although the chickens were not vaccinated against any poultry diseases, serum antibodies to Newcastle disease, infectious bursal disease and infectious bronchitis were detected.     

Vertical Flux of Biogenic Carbon in the Ocean: Is There Food Web Control?

Models of biogenic carbon (BC) flux assume that short herbivorous food chains lead to high export, whereas complex microbial or omnivorous food webs lead to recycling and low export, and that export of BC from the euphotic zone equals new production (NP). In the Gulf of St. Lawrence, particulate organic carbon fluxes were similar during the spring phytoplankton bloom, when herbivory dominated, and during nonbloom conditions, when microbial and omnivorous food webs dominated. In contrast, NP was 1.2 to 161 times greater during the bloom than after it. Thus, neither food web structure nor NP can predict the magnitude or patterns of BC export, particularly on time scales over which the ocean is in nonequilibrium conditions.     

Attitudes of farm consultants in the South Island of New Zealand towards the role of veterinarians in farm businesses

AIMS: To assess the attitude of dairy farm consultants to the role of veterinarians on dairy farms and whether they viewed veterinary advice as impartial, free from commercial bias and central to farm productivity and profitability.

METHODS: A telephone survey was commissioned in September 2014 of 36 full-time farm consultants in the Canterbury and Otago region of New Zealand using a pre-prepared questionnaire to explore their attitudes towards the veterinary profession. Of those approached, 25 completed the survey.

RESULTS: The consultants surveyed agreed or strongly agreed (21/23) that they were the custodians of animal health expenditure on farms, which was seen as an expense to be controlled (19/25 agreed or strongly agreed). This view was held more strongly (9/9 agreed or strongly agreed) by consultants with >5 years’ professional experience, compared to 10/16 consultants with ≤5 years’ experience. Most consultants (24/25) disagreed that they did not respect veterinary advice, but agreed (24/25) that veterinarians almost always had a vested interest in the advice that they gave. The role of veterinarians was seen by respondents to be mainly treatment of sick animals (22/25) and provision of animal health products (24/25), but not in maximising farm profitability (selected by 8/25 respondents). Consultants viewed their own roles as providing advice on the influence of animal health on farm profitability (21/25), nutrition (22/25) and reproduction (20/25). Most respondents (21/25) stated that reducing disease and animal health issues was important, but they (21/25) also identified a reduction in farm animal health expenditure as a measure of success. Only 7/25 consultants felt that they should work in partnership with veterinarians.

CONCLUSIONS: This was a small scale study from one region of New Zealand but it indicates that consultants are ambivalent about the role and value of working more closely with veterinarians, and about the benefit that veterinary intervention may bring to a farm’s profitability.

CLINICAL RELEVANCE: More successful veterinary involvement on dairy farms will follow from a better understanding of how other rural professionals are involved in the farm’s management and in meeting the individual farmer’s goals and motivations.     

Effects of IGF‐1 on In Vitro Culture of Bovine Preantral Follicles are Dose‐Dependent

This study aimed at assessing the effect of different concentrations of the growth factor similar to insulin 1 (IGF‐1) in the development, survival and ultrastructure of the bovine preantral follicles cultured in situ. Fragments of bovine ovarian cortical tissue were cultured during 1 and 7 days in 1 ml of α‐MEM⁺, supplemented with different concentrations of human recombinant IGF‐1 (0, 30, 70 and 100 ng/ml), in an incubator at 37°C and 5% of CO₂ in 24‐well plates with total replacement of the medium every 2 days. Non‐cultured ovarian fragments (control) and ovarian fragments cultured during 1 and 7 days were processed for classic histology, mechanical isolation and electron transmission microscopy (ETM). Parameters such as normality, viability, activation, development, diameter and ultrastructure were evaluated. All statistical analyses were carried out using sas Version 9.2. The results showed that the percentage of follicles morphologically normal in the IGF‐1 30 ng/ml treatment was similar to the fresh control (p > 0.05) both on the day 1 and on the day 7 of in vitro culture. In the viability analysis, the cultured treatments maintained the percentage of viable follicles during the entire culture period (p > 0.05). After 7 days of culture, the IGF‐1 30 ng/ml treatment showed higher percentages of developing follicles (48.33%) than those of the fresh control (22.22%) and the cultured treatments (p < 0.05). Also, after 7 days of culture, IGF‐1 30 ng/ml presented a higher follicular diameter when compared to the control and other concentrations of IGF‐1 tested. Ultrastructurally, the non‐cultured control and IGF‐1 30 ng/ml, after 7 days of culture, showed conserved oocytes, nuclei and organelles. Hence, it is concluded that IGF‐1 30 ng/ml was the most efficient concentration for the development of bovine preantral follicles cultured in vitro.     

Clinical and pathological findings associated with congenital hypovitaminosis A in extensively grazed beef cattle

Objective   To determine the cause of exceptionally high mortality (41.4%) in perinatal calves on a beef cattle property 50 km south-west of Julia Creek in north-western Queensland.
Design   Investigations were based on clinical assessment of affected calves and laboratory analysis of pre- and postmortem specimens taken from 12 calves aged from 6 to 36 h of age.
Methods   Associations between gross and histopathological findings and biochemical analyses conducted on serum and tissue samples were examined in relation to clinical observations.
Results   Clinical signs varied, but commonly included mild to severe ataxia, difficulty finding a teat and sucking, blindness (partial or complete, as judged by avoidance of obstacles) and depression with prominent drooping of the head. Gross and histopathological findings included herniation of the cerebellar vermis through the foramen magnum, squamous metaplasia of interlobular ducts in the parotid salivary glands and Wallerian degeneration of the optic nerves. Biochemical analysis of serum and liver samples available from four of the calves revealed low or undetectable levels of both vitamin A and vitamin E.
Conclusion   Although vitamin E is known to have a sparing effect on vitamin A, the role (if any) played by deficiency of this vitamin was uncertain. The combination of clinical signs, postmortem findings, histopathological features and biochemical findings indicate that gestational vitamin A deficiency was highly likely to have been an important contributor to perinatal calf mortalities in this herd.