Milk production and blood metabolites of dairy cattle as influenced by thermal-humidity index

The effects of high thermal stress on serum protein metabolites, milk production of transition dairy cows in semi-arid areas in South Africa were evaluated. Forty, ±?8 months pregnant, Jersey heifers (±?26 months) in zero grazing management were selected during summer from two semi-arid communal areas. Summer thermal-humidity index (THI) of the areas were THI-1 (72–83: extreme caution) and THI-2 (75–87: danger). Blood samples were collected (21 days pre-partum, and 21 and 75 days post-partum) and analysed for serum protein metabolites. Milk yield was recorded daily and samples collected for milk fat, protein, lactose and urea nitrogen analysis. Heifers in THI-2 had lower (P?<?0.05) total serum proteins, albumin and blood urea nitrogen than THI-1. Post-calving, cows in THI-1 had higher (P?<?0.05) TP (73.4 vs 67.9 g/l) and BUN (4.61 vs 3.77 mmol/l) at 21 DIM, and lower (P creatinine at 21 and 75 DIM than THI-2 group. Milk yield, fat and protein in THI-2 were all lower (P?<?0.05) than THI-1 21DIM. The results confirm that heat stress affects utilisation of nutrients in transition dairy cows.

     

Effect of repeated freeze-thaw cycles on routine plasma biochemical constituents in canine plasma

BACKGROUND: The effect of repeated freeze-thaw cycles on plasma constituents has not been assessed in dogs, although such a procedure is not uncommon to use in routine laboratory practice. OBJECTIVE: To assess the effect of freeze-thaw cycles on routine plasma constituents in healthy dogs. METHODS: Six healthy adult dogs were used. Blood was sampled and placed in heparinized tubes. After centrifugation, plasma was separated into 5 aliquots. One aliquot was considered as the reference aliquot and used immediately for the assay of all of the biochemical constituents. All of the other aliquots were stored at 20 degrees C. Three aliquots underwent 1, 2, or 3 freeze-thaw cycles during a 1- to 3-day period. The last aliquot remained at 20 degrees C throughout the study and was thawed on the third day. The following biochemical constituents were assayed: glucose, urea, creatinine, total proteins, sodium, potassium, chloride, calcium, phosphates, aspartate aminotransferase (AST), alanine aminotransferase (ALT), creatine kinase (CK), and alkaline phosphatase (ALP). RESULTS: No clinically relevant change was observed between the different aliquots for all of the constituents. CONCLUSION: Repeated freeze-thaw cycles do not cause changes in the biochemical constituents studied in canine plasma.     

Ocular findings in two colonies of gray mouse lemurs (Microcebus murinus)

OBJECTIVE: To determine the incidence and describe the characteristics of cataracts and other ocular lesions found in two colonies of gray mouse lemurs (Microcebus murinus). ANIMALS STUDIED: A total number of 218 mouse lemurs (age range: 4 months-11 years) were included in this study. All individuals were property of the Muséum National d'Histoire Naturelle (France), and were housed either in Paris (colony #1: 75 animals examined), or in Brunoy (colony #2: 143 animals). METHODS: Ocular examinations were performed on all animals before and after pupil dilation, and included slit-lamp biomicroscopy and indirect ophthalmoscopy. In both colonies, a limited number of individuals were re-examined between several months and 2 years following the initial eye examinations. The eyes of five mouse lemurs with incipient or immature cataracts that died during this period were collected, and processed for routine histopathologic examination. RESULTS: A high incidence of cataracts was observed in both colonies (48% in colony #1; 21% in colony #2). Cataracts were predominantly bilateral, started in the anterior and/or posterior subcapsular area, and appeared to be slowly progressive. The earliest age at which lens opacities were observed was 3.5 years, and more than 50% of mouse lemurs over 7 years of age were diagnosed with cataracts. Complete cataracts led to blindness and were occasionally associated with other ocular lesions. CONCLUSION: We report a high incidence of acquired, slowly progressive, bilateral cataracts in two colonies of mouse lemurs (Microcebus murinus). Further studies need to be conducted to determine the cause of this disease in this species.     

Apparent digestibility and microbial protein yield of Desmodium uncinatum,Mucuna pruriens and Vigna unguiculata forage legumes in goats

This study examined the effects of adding forage legumes as protein supplements to poor-quality natural pasture (veld) hay offered to goats on microbial protein yield and nitrogen metabolism. Four indigenous Nguni-type goats were used in a 4×4 Latin cross-over design experiment. Goats were randomly allocated to four dietary treatments comprising commercial goat feed (GF), veld hay supplemented with cowpea (CW), velvetbean (VB) or silverleaf desmodium (SD). Microbial protein yields were determined using the purine derivatives technique and nitrogen retention was calculated from the digestible organic matter intake. Total nitrogen intake was significantly higher in the GF followed by CW, SD and VB, respectively. Microbial protein supply, calculated microbial true protein and digestible microbial true protein were affected (P<0.05) by legume supplementation. Animals on poor-quality forages had the most efficient microbial protein synthesis. However, supplementation of hay failed to meet the maintenance requirements of animals as evidenced by negative nitrogen balances in VB and SD. The efficiency of utilisation of nitrogen in the supplements could have been limited by unavailable fermentable metabolisable energy in the diets. Supplementation of poor-quality veld hay with legume forages could improve utilisation, especially in the dry season.     

Screening for methicillin-resistant staphylococci in dogs admitted to a veterinary teaching hospital

This study investigated the nasal carriage of methicillin-resistant staphylococci (MRS) in dogs (n=177) prior to medical examination or surgery in a veterinary teaching hospital. Nasal swab samples were collected after induction of anaesthesia and incubated overnight in salt enriched trypticase-soy broth. Cultures were analysed on two different agar media containing cefoxitin. Suspected MRS isolates were genotypically identified and characterised by antimicrobial susceptibility testing and staphylococcal cassette chromosome mec (SCCmec)-typing. Methicillin-resistant Staphylococcus aureus (MRSA) isolates were additionally characterised by spa-typing and multilocus sequence typing. The presence of Panton-Valentine leukocidin (pvl) genes was determined by PCR. MRS carriage was compared between animals with or without an infectious process. Two MRSA were isolated, both belonging to typical Belgian human hospital clones and lacking pvl. Additionally a methicillin-resistant Staphylococcus haemolyticus carrying a type V SCCmec was detected. No relationship was observed between MRS carriage and presence of infections. The results suggest that MRS are present in dogs originating from the community, albeit at a low prevalence. This could pose risks for cross contamination of dogs and their owners.     

Environmental factors at different spatial scales governing soil fauna community patterns in fragmented forests

Spatial and temporal changes in community structure of soil organisms may result from a myriad of processes operating at a hierarchy of spatial scales, from small-scale habitat conditions to species movements among patches and large-sale landscape features. To disentangle the relative importance of spatial and environmental factors at different scales (plot, patch and landscape), we analyzed changes in Collembola community structure along a gradient of forest fragmentation, testing predictions of the Hierarchical Patch Dynamics Paradigm (HPDP) in different European biogeographic regions (Boreal, Continental, Atlantic, Mediterranean, Alpine). Using variance partitioning methods, based on partial CCAs, we observed that the independent effect of environmental processes was significantly explaining Collembola community variance in all regions, while the relative effect of spatial variables was not significant, due to the observed high levels of landscape heterogeneity along the gradient. Environmental factors at the patch and plot scales were generally significant and explained the larger part of community changes. Landscape variables were not significant across all study sites. Yet, at the landscape level, an increase in forest habitat and proximity of forest patches were showed to have an indirect influence on local community changes, by influencing microhabitat heterogeneity at lower spatial scales in all studied regions. In line with HPDP, large-scale landscape features influenced spatio-temporal changes in soil fauna communities by constraining small-scale environmental processes. In turn, these provided mechanistic understanding for diversity patterns operating at the patch scale, via shifts in community weighted mean of Collembola life-forms occurring in local communities along the fragmentation gradient.     

Issues and challenges in landscape models for agriculture: from the representation of agroecosystems to the design of management strategies

Context

Agroecosystems produce food and many other services that are crucial for human well-being. Given the scales at which the processes underlying these services take place, agricultural landscapes appear as appropriate spatial units for their evaluation and management. The design of sustainable agricultural landscapes that value these services has thus become a pressing issue but faces major challenges stemming from the diversity of processes, their interactions and the number of scales at stake. Agricultural landscape modelling can provide a key contribution to this design but must still overcome several difficulties to offer reliable tools for decision makers.

Objectives

Our study aimed at shedding light on the main scientific and technical difficulties that make the building of landscape models that may efficiently inform decision-makers a complex task, as well as translating them in terms of challenges that can be further investigated and discussed.

Methods

We examine current issues and challenges and indicate future research needs to overcome the scientific and technical obstacles in the development of useful agricultural landscape models.

Results

We highlight research perspectives to better couple landscape patterns and process models and account for feedbacks, integrate the decisions of multiple stakeholders, consider the spatial and temporal heterogeneity of data and processes, explore alternative landscape organisations and assess multiobjective performance.

Conclusion

Coping with the issues and challenges discussed in this paper should improve our understanding of agroecosystems and give rise to new hypotheses, thereby informing future research.

     

Evaluating critical factors to the economic feasibility of semi-intensive pig rearing in western Kenya

The purpose of this research is to assess how season, ADG, opportunity costs of farm-grown feeds, pig weight, and butcher price variation impact the economic potential of semi-intensive pig rearing. We developed a unique algorithm that emulates least-cost pig feeding and used it to assess the impact of the aforementioned factors on farmers’ maximum revenue and profit potential when pigs are sold to local butchers in western Kenya. When considered as independent factors influencing feed costs to grow a pig to a market weight of 30 kg, variation in ADG, opportunity cost of feed, and weaning season resulted in feed cost differences of up to 982, 947, and 379 Kenyan shillings (KES), respectively. The variation in revenues attributable to butcher or butcher negotiation and seasonal variance of butcher prices for a 30 kg pig was 744 and 225 KES, respectively. Feed items most commonly chosen for least-cost feed rations were small dried fish, cooked ground maize, whole maize, millet, cassava foliage, sweet potato vines, bone meal, avocado, and mango. Smallholder farmers who can feed pigs to reach higher ADG have lower opportunity costs of feeds and/or who effectively bargain with butchers can benefit from semi-intensive pig rearing. Farmers without access to at least some zero-cost feeds and farmers with opportunity costs of feeds exceeding 50 % of the market price will not earn positive returns from semi-intensive pig rearing.     

Laboratory and field investigations using indigenous entomopathogenic nematodes for biological control of Plutella xylostella in Kenya

This study was undertaken to determine the potential utility of entomopathogenic nematodes for management of diamondback moth (DBM) larvae in Kenya. Five Kenyan EPN isolates, Heterorhabditis indica, Steinernema karii, Steinernema weiseri, Steinernema sp. and Heterorhabditis taysearae were tested for their ability to penetrate DBM and their speed of kill (LT₅₀). Heterorhabditis indica and S. weiseri were found to have the quickest rate of kill and S. weiseri was found to have the largest proportion of nematodes penetrating. Three of the isolates, Steinernema sp. (95), S. weiseri and H. indica, were used in a field experiment to test their ability to reduce DBM populations and damage to kale. All three nematodes caused significant reductions in populations of DBM and DBM damage, with the population reductions being similar to those caused by application of Bacillus thuringiensis ssp. kurstaki. This study shows that EPNs have great potential that should be exploited in the management of DBM in Kenya.