Long‐term assessment of horses and ponies post exposure to monensin sodium in commercial feed

Reasons for performing study: Acute monensin intoxication in equids is well described; however, the long‐term effects of sublethal intoxication and ability to return to previous use are less well understood. Long‐term observations may allow improved estimation of prognosis in cases of sublethal intoxication. Objectives: To assess horses and ponies exposed to sublethal amounts of monensin for evidence of chronic sequelae and ability to return to prior/intended use. Methods: Twenty‐nine horses and 8 ponies were assessed utilising serum biochemistry, treadmill exercise stress testing, electrocardiography, and pre‐ and post exercise echocardiography ≥6 weeks after ingestion of monensin‐contaminated feed. Animals with evidence of monensin‐induced cardiomyopathy were re‐examined after a period of rest of ≥11 months. Follow‐up information was obtained by owner telephone interview ≥52 months after exposure. Results: During resting echocardiography, 11 animals had reduced/low‐normal left ventricular fractional shortening (FS); an increase in FS in 8 of these animals was measured ≥11 months later. Six animals had reduced or low‐normal FS during post exercise echocardiography. Two horses had ventricular premature depolarisations during exercise. Follow‐up information was available for 35 animals: 21 returned to athletic/reproductive use, 13 were retired immediately and one died. Mean FS increased significantly (P<0.001) between initial and second examination in 15 animals that underwent resting echocardiography on 2 occasions. Conclusions: Some equids exposed to sublethal doses of monensin may not develop permanent myocardial disease and a return to athletic/reproductive use is possible. Potential relevance: Exercise stress testing, echocardiography and electrocardiography may be useful for detection and monitoring of cardiac dysfunction in equids exposed to monensin and determining whether a return to athletic/reproductive use is possible.     

Cutaneous habronemiasis in a 9‐year‐old Arab gelding in the United Kingdom

Cutaneous habronemiasis causes ulcerative granulating lesions in the skin of equids. Dramatic exuberant tissue may be seen, which becomes traumatised by the horse. To the authors' knowledge, cutaneous habronemiasis has not previously been documented on the distal limb of horses in the UK. Cutaneous habronemiasis should be considered as a potential differential diagnosis for ulcerative granulating skin lesions on the distal limb of the horse.     

A quantitative method for the determination of cyclopropenoid fatty acids in cottonseed, cottonseed meal, and cottonseed oil (Gossypium hirsutum) by high-performance liquid chromatography

Cyclopropenoid fatty acids (CPFAs), found in cottonseed, have been shown to have detrimental health effects to susceptible livestock. Previous quantitative analytical methods for the determination of CPFAs expressed these acids in terms of their relative abundance with respect to other fatty acids in the oil, necessitating the concurrent analysis of other fatty acids. The proposed analytical method describes the quantitation of three relevant CPFAs for cotton (malvalic acid, sterculic acid, and dihydrosterculic acid) in cottonseed in micrograms per gram fresh weight of sample. The method involves extraction of the oil, saponification, and derivatization of the free fatty acids with 2-bromoacetophenone to give the phenacyl esters. These esters are then separated by dual-column reverse-phase high-performance liquid chromatography and quantitated via external standards. This is the first method to include external calibration standards for CPFAs and, as such, is capable of direct quantification with no further data conversion required. CPFA data generated from the analysis of cottonseed, cottonseed meal, and cottonseed oil produced in the United States in 2002 are presented.     

L-Canavanine, a Dietary Nitrogen Source for the Seed Predator Caryedes brasiliensis (Bruchidae)

Larvae of the bruchid beetle Caryedes brasiliensis (Bruchidae) develop entirely within the seed of the neotropical legume Dioclea megacarpa. The seed contains an appreciable concentration of L-canavanine, a potent antimetabolite and structural analog of L-arginine. This bruchid beetle uses the nitrogen stored in this toxic allelochemical as an effective dietary nitrogen source for amino acid biosynthesis.     

Nest box design and nesting material in a deep litter house for laying hens

1. Preferences of hens for different types of nest box were tested in two deep litter pens, each containing 300 Isabrown laying hens. Four types were offered: traditional wooden nests with litter, metal rollaway nests with plastic liners, wooden rollaway nests with artificial turf and autonests.

2. Most eggs were laid in traditional nests (70% in pen 1, 66% in pen 2). Metal rollaways were the next preferred type. These preferences were confirmed by analysis of records from individual nest boxes, and by observations of hens marked with wing tags.

3. Choice of nesting material was tested in one pen of 370 hens. Traditional nests were provided, containing either wood shavings or a mixture of buckwheat and oat husks.

4. Preferences for type of nesting material were equivocal. The majority of eggs were laid on wood shavings initially, but on buckwheat/oat husks later. Individual hens were inconsistent in their choice. A deep (100 mm) layer of nesting material was preferred to a shallow (25 mm) layer.

5. Individual, wooden nest boxes incorporating buckwheat/oat husk nesting material on a movable belt are probably the most suitable system for automation of egg collection in deep litter houses.     

Simple phosphorus saturation index to estimate risk of dissolved P in runoff from arable soils

Abstract. There is increasing evidence that phosphorus has been accumulating in the surface horizons of agricultural soils to the extent that some soils represent a potential diffuse source of pollution to surface waters. The relationships between equilibrium phosphorus concentration at zero sorption (EPC ₀) of soil and a number of soil physicochemical variables were investigated in the surface layers of arable and grassland agricultural soils sampled from the Thame catchment, England. Soil EPC₀ could be predicted from an equation including soil test (Olsen) P, soil phosphate sorption index (PSI) and organic matter content (OM) (R²=0.88; P <0.001) across a range of soil types and land use. The simple index Olsen P/PSI was found to be a good predictor of EPC₀ (R²=0.77; P <0.001) and readily desorbable (0.02 m KCl extractable) P (R²=0.73; P <0.001) across a range of soil types under arable having soil organic matter contents of <10%.