Crimidine (2‐chloro‐4‐(dimethylamino)‐6‐methylpyrimidine) poisoning in a dog due to ingestion of the rodenticide Castrix®

The diagnosis and treatment of a case of crimidine poisoning in a dog are described. Presenting signs were seizures and vomiting. The vomitus contained a purple coloured cereal grain. The signs and grain colour were suggestive for a rodenticide with convulsive effects The diagnosis of crimidine poisoning was made by thin layer chromatography and was later confirmed by finding the source of the poison. Except for the administration of Vit B6, the specific antidote for crimidine, general treatment principles for poisoning were followed. The treatment of crimidine poisoning is time consuming and requires intensive care facilities.     

Short‐term effects of cattle‐to‐sheep ratio and stocking rate on patch grazing in sour grassveld

Abstract

The short‐term effects of stocking rate (AUE ha^?1) and cattle‐to‐sheep ratio on the extent and severity of patch grazing and on patch size were evaluated. The extent of patch grazing was proportional to stocking rate, and livestock species had a small but significant effect. Patch size was also a function of stocking rate. Cattle and sheep had similar effects on patch size distribution when stocked at the same number of AUE ha^?1. The severity of grazing within a patch was influenced by both stocking rate and cattle‐to‐sheep ratio. Recommendations that cattle should be grazed together with sheep and that cattle should be in greater proportion (in terms of AUE ha^?1) than sheep, which are aimed at limiting the severity of grazing by sheep, are supported. However, severe grazing within patches is an inevitable consequence of sheep grazing irrespective of the stocking rate or cattle‐to‐sheep ratio applied.     

Response of broiler chicks to threonine‐supplemented diets to 4 weeks of age

1. Two experiments were carried out to determine the response of broiler chicks to threonine‐supplemented diets between 10 and 28 d and 7 and 21 d of age, respectively.

2. In the first experiment female broiler chicks were fed on 11 experimental diets. Two iso‐energetic basal diets (diets 1 and 2) were prepared with 200 and 160 g CP/kg and 7·6 and 6·0 g threonine/kg respectively. Both diets contained 11·5 g lysine and 8·7 g sulphur‐containing amino acids/kg. Diet 3 was composed of diet 2, supplemented with all essential and non‐essential amino acids (EAA and NEAA, respectively) except threonine, to the concentrations of the amino acids in diet 1. The NEAA were added as a combination of glutamic acid and glycine. Diets 4 to 11 had the same compositions as diet 3, but contained increasing amounts of threonine.

3. For birds fed on diet 2, gain was significantly lower and food/gain ratio was significantly higher than for birds fed on diet 1. Supplementation with EAA, NEAA and threonine to the same concentrations in diet 1 resulted in a performance similar to that found on diet 1.

4. In experiment 2, male and female broiler chicks both received 10 experimental diets. Diet 1 contained 220 g CP/kg and 8.5 g threonine/kg, diet 2 contained 160 g CP/kg from natural raw materials and 6 g threonine/kg. Both diets contained 12·4 g lysine and 9·3 g sulphur‐containing amino acids/kg. Basal diet 2 was supplemented with all EAA and NEAA to the concentrations of basal diet 1, except for threonine. Diets 3 to 10 had the same compositions as the supplemented diet 2, but contained increasing amounts of threonine.

5. For male and female chicks on diet 2, gain was significantly lower and food/gain ratio significantly higher than those on diet 1. Diet 10 (160 g CP/kg plus all EAA, including threonine, and NEAA supplemented to the concentrations of diet 1) resulted in the same performance as diet 1.

6. The results indicate that, when low protein maize‐soyabean meal diets supplemented with EAA and NEAA with 13·31 MJ ME/kg were fed to male and female broiler chicks until 21 d of age, improvements in gain and food/gain ratio were obtained when the dietary threonine content was increased to 7·25 g/kg. When female chicks were fed threonine‐supplemented diets to 28 d of age, improvement in gain and food/gain ratio was obtained when the threonine concentrations were increased to 6·32 g/kg diet.

7. Curves have been fitted to the data, from which a cost‐benefit analyses can be made and an optimum threonine dose calculated, using local prices.     

The effect of feeding low‐protein diets to pullets from hatch to point‐of‐lay and the quantitative restriction of food during the subsequent laying period

Pullets from two commercial breeds were fed on diets of similar energy content but with 19% or 16% crude protein to 8 weeks of age and from 8 to 20 weeks of age on one of three isoenergetic diets containing either 12, 14 or 16% crude protein. At 20 weeks the birds were offered a conventional layers’ diet containing 16% crude protein either ad libitum or on a daily food intake of 100 g for a further 32 weeks.

The results indicate that with certain breeds the dietary protein levels can be lowered to approximately 16% during the o to 8‐week period and to approximately 12% during the 8 to 20‐week period without adversely affecting egg production. However, variations in the laying performance of the different breeds appear to be dependent on the amount of protein fed in the first eight weeks of life. Significant breed effects were observed throughout the experiment and although restricted feeding during the laying period substantially reduced the food intake it also had a detrimental effect on the rate of egg production and on the total weight of eggs produced.     

Use of the Cortisol‐to‐ACTH Ratio for Diagnosis of Primary Hypoadrenocorticism in Dogs

Background

The ACTH stimulation test is currently required for definitive diagnosis of hypoadrenocorticism. Increased cost of synthetic ACTH (cosyntropin) has prompted a search for alternative diagnostic methods.

Objective

The purpose of this study was to determine whether a cortisol‐to‐ACTH ratio (CAR) can be used to differentiate dogs with hypoadrenocorticism from normal dogs and those with nonadrenal illness.

Animals

Eight healthy dogs (H), 19 dogs with nonadrenal illness (NAI), and 15 dogs with hypoadrenocorticism (HAD).

Methods

Dogs in the HAD group were retrospectively identified from PUVTH medical records. The NAI group consisted of hospitalized dogs with clinical signs, clinicopathologic findings, or both, consistent with a diagnosis of hypoadrenocorticism, but in which hypoadrenocorticism was ruled out based on ACTH stimulation test results. Healthy dogs were recruited from hospital staff and students. Endogenous ACTH concentrations and cortisol concentrations before and after ACTH stimulation were measured in all dogs.

Results

Baseline cortisol concentration was significantly lower, and ACTH concentration was significantly higher, in the HAD group versus the H and NAI group (P < .001). However, there was overlap among groups. Cortisol‐to‐ACTH ratio was significantly lower in the HAD group versus the H and NAI groups (P < .001), and there was no overlap between the HAD group and the other 2 groups.

Conclusions and Clinical Importance

CAR can be used for definitive diagnosis of primary hypoadrenocorticism.     

From Mendel to multi‐national in poultry breeding 1

1. This paper attempts to identify and evaluate the contributions of the geneticist to the continuing role in productivity that has been evident over the past 40 years or more.

2. The importance of the fowl in establishing the validity of Mendel's laws of inheritance is shown, together with the findings that made the bird the species of choice for much of the early work on animal genetics.

3. The early development of the egg production industry is outlined and the impetus given to this new commercial venture by the application of genetic principles, described. A review of the poultry meat sector is also given.

4. The role of the geneticist in increasing productivity in terms of numbers of eggs laid, meat produced and quantities of food required to produce both products is discussed and quantitative data presented.

5. The prospects for further improvements in productivity are assessed, particularly in the context of adverse environments both climatic and social. The prospective role of genetic engineering is also considered.     

Response of broiler chickens to well‐balanced protein mixtures

1. Four experiments were conducted on broiler chickens between one and three weeks of age to determine their response to dietary protein concentrations.

2. Diets prepared by serial dilution of a concentrated protein mixture, well‐balanced with respect to all essential amino acids, were fed in three experiments, while in a fourth experiment, a lysine‐deficient protein mixture was used.

3. Response curves relating body‐weight gain to increasing concentrations of protein and of lysine intake are presented.

4. A table is presented from which optimum protein intakes can be calculated according to changes in input and output costs and changes in growth potential of the chickens.     

Response of three class‐IV major histocompatability complex haplotypes to Eimeria acervulina in meat‐type chickens

1. The importance of MHC genes and background genes in controlling disease resistance, including resistance to avian coccidiosis, has not been clarified in meat‐type chickens.

2. The role of class IV MHC genes in resistance to Eimeria acervulina was assessed in F2 progeny of a cross between 2 meat‐type lines, selected divergently for immune response to Escherichia coli.

3. Disease susceptibility was assessed by lesion score, body weight, packed cell volume and carotene absorption.

4. Chickens with the “K” class IV MHC haplotype had lower lesion scores than chickens with “F” and “A” haplotypes.

5. Plasma carotene concentrations were higher in chickens with “K” haplotype and lower in chickens with “F” and “A” haplotypes whereas body weight and packed cell volume were less sensitive measures of Eimeria infection.

6. Eimeria acervulina resistance appears to be associated with MHC class IV genes; information about MHC haplotypes may be useful in selecting for increased resistance of meat‐type chickens to coccidiosis.     

Use of delayed‐type hypersensitivity test to diagnose brucellosis in calves born to infected dams

Summary

Calves (n = 2) born to dams with experimentally induced brucellosis, and calves (n = 4) born to dams with naturally occurring infection were examined by the delayed‐type hypersensitivity (DTH) test for possible B. abortus infection. The results were compared with the serum agglutination test, complement fixation test, and Coombs test. Five calves were nursed by their dams for 8–10 weeks after birth. One calf was separated from its dam and fed artificial milk.

Three to five months after birth, four calves tested seropositive in the serologic tests. Antibodies were detected in one calf as early as 1 week after birth. The calf fed on artificial milk was seronegative 4–5 weeks after birth. All calves reacted to the DTH test antigen from week 12 until the end of the experiment, even though serologic tests were negative. We conclude that the DTH test is a valuable technique for diagnosing Brucella in calves born to infected dams.     

Responses of Italian ryegrass to phosphorus on highly‐weathered soils

Italian ryegrass (Loliwn multiflorum cv. Midmar) responses to fertilizer P were studied in field experiments under irrigation on highly‐weathered ferrallitic soils at two localities in Natal. Each experiment was conducted over two seasons (1985 and 1986), the pasture being re‐established after the first season. Large dry matter yield responses to P were measured on both soils. Phosphorus effects were greatest during the establishment phase (autumn) and, on the colder site, in spring. Concentrations of P in herbage were much lower in winter than in autumn or summer. The greater responsiveness to P in spring and the lower P concentrations in herbage during the colder months suggested that restricted P uptake contributed to yield reductions in winter. Relationships between ryegrass P concentrations and yield indicated substantial within‐season variations in internal P requirement for maximum yield. This detracts from the usefulness of routine herbage P analyses for assessing ryegrass P sufficiency. However, soil analysis using an alkaline extractant (NH₄HCO₃/EDTA/NH₄F at pH 8.0), showed promise for predicting responsiveness to P. Concentrations of P in Italian ryegrass were well below the requirements reported in the literature for most classes of grazing ruminants, particularly during the colder months.     

Use of Contrast‐Enhanced Fluid‐Attenuated Inversion Recovery Sequence to Detect Brain Lesions in Dogs and Cats

Background

The diagnostic value of a contrast‐enhanced T2‐weighted FLAIR sequence (ceFLAIR) in brain imaging is unclear.

Hypothesis/Objectives

That the number of brain lesions detected with ceFLAIR would be no greater than the sum of lesions detected with nFLAIR and ceT1W sequence.

Animals

One hundred and twenty‐nine animals (108 dogs and 21 cats) undergoing magnetic resonance imaging (MRI) of the head between July 2010 and October 2011 were included in the study.

Methods

A transverse ceFLAIR was added to a standard brain MRI protocol. Presence and number of lesions were determined based on all available MRI sequences by 3 examiners in consensus and lesion visibility was evaluated for nFLAIR, ceFLAIR, and ceT1W sequences.

Results

Eighty‐three lesions (58 intra‐axial and 25 extra‐axial) were identified in 51 patients. Five lesions were detected with nFLAIR alone, 2 with ceT1W alone, and 1 with ceFLAIR alone. Significantly higher numbers of lesions were detected using ceFLAIR than nFLAIR (76 versus 67 lesions; P = 0.04), in particular for lesions also detected with ceT1W images (53 versus 40; P =.01). There was no significant difference between the number of lesions detected with combined nFLAIR and ceT1W sequences compared to those detected with ceFLAIR (82 versus 76; P =.25).

Conclusion and Clinical Importance

Use of ceFLAIR as a complementary sequence to nFLAIR and ceT1W sequences did not improve the detection of brain lesions and cannot be recommended as part of a routine brain MRI protocol in dogs and cats with suspected brain lesions.     

Maximum nutritional response to poor‐quality protein and amino acid utilisation

1. Although the theory of responses to amino acids suggests that, providing sufficient of the limiting amino acid is fed, it should be possible to elicit maximum growth response, maximum response is not usually elicited by poor‐quality proteins.

2. It has been suggested that this failure to elicit maximum response is a reflection of poorer limiting amino acid utilisation from poor‐quality proteins. This interpretation conflicts with the theory of general amino acid imbalance which proposes that amino acid excesses do not impair the utilisation of the limiting amino acid.

3. Three protein mixtures of different quality were made by mixing maize gluten meal and soyabean protein concentrate in constant proportions, supplementing with tryptophan, threonine and arginine to adequacy and varying amino acid score (0'62, 0^‐71 or = 1–0) by varying additions of free lysine. The 3 mixtures were diluted with protein‐free ingredients to produce 3 diet series, each providing 3–7, 6–5, 9–2, 120, 14–8 and 17–5 g lysine per kg. Each diet was fed to 4 cages of 2 chickens each from 4 to 14 d of age in a randomised block experiment. Food intake, body‐weight and body‐nitrogen gain were measured.

4. Differences in protein quality were confirmed by regression analyses of body‐weight response to protein intake (Net Protein Ratio) and body‐nitrogen response to nitrogen intake (Net Protein Utilisation) in the linear range. Regression analyses in the linear range of body‐weight or body‐nitrogen response to lysine intake showed no adverse effect of protein quality on lysine utilisation. Curvilnear analysis (Reading flock response model) confirmed this finding.

5. Maximum response could not be obtained with the poorest protein quality. It is illogical to invoke impaired utilisation of the limiting amino acid to explain this. A small decrease in net energy yield of the diet may be sufficient to explain the effect, but it is more likely that the depletion of the limiting amino acid from tissue (muscle) protein which results from feeding poor‐quality protein explains the effect.     

The contribution of anorexia to reduced growth in zinc‐deficient chickens

1. It was shown, using a paired‐feeding technique, that the growth depression in zinc‐deficient chicks was largely caused by the greatly reduced consumption of the deficient diet.

2. Chicks receiving a zinc sulphate solution directly into the crop ate an amount of zinc‐deficient diet similar to that of the zinc‐sufficient diet eaten by the control chicks; palatability was thus ruled out as the cause of the anorexia.

3. Only chicks receiving the zinc‐deficient diet displayed signs of zinc deficiency.     

Response to long‐term selection for egg production in laying hens

1. A White Leghorn line was selected for part‐record hen‐housed number of eggs from 1962 to 1990. Genetic changes were estimated as deviations from its unselected control line.

2. Over the first 10 generations with selection almost exclusively for number of eggs to the age of 273 d, all traits, except rate of mortality, showed significant changes. Regressions per year were: 273 d production, 3.07 eggs; 497 d production, 5.18 eggs; production from 274 to 497 d, 2.43 eggs; age at first egg, ‐2.33 d; mean weight of first 10 eggs, ‐0.82 g; body weight at 497 d, ‐19.02 g and rate of mortality, 0.19%.

3. Over the rest of the period increasing selection pressure for egg weight has been applied. This resulted in positive changes for this trait and no or small negative changes in egg number.

4. In general, heritabilities and genetic correlations did not change over the period of selection. The heritability of the main trait of selection, production to 273 d was 0.19 ± 0.04 and heritabilities of egg size traits about 0.50.

5. The genetic correlation between egg production to 273 d and mean weight of first 10 eggs was estimated as ‐0.37 ± 0.06 but from the observed response a realised genetic correlation of ‐0.97 was calculated.     

Effects on chick performance and nutrient digestibility of an endo‐xylanase added to a wheat‐ and rye‐based diet in relation to fat source

1. A study with growing chicks investigated the effects of an inclusion of an endo‐xylanase preparation (LYXASAN®) to a wheat‐ and rye‐based diet on performance and nutrient digestibility in relation to the fat source.

2. The basal diet contained 500 g wheat and 100 g rye/kg of diet. The basal diet was supplemented with either 65 g soya oil/kg or 60 g blended animal fat and 5 g soya oil/kg.

3. Endo‐xylanase added to the soya oil diet did not affect weight gain, but there was a numerical improvement in food conversion efficiency which was not statistically significant. When the endo‐xylanase preparation was added to the blended animal fat diet, both weight gain and food utilisation were improved by 9.5% and 6.0%, respectively (P< 0.05).

4. Digestibilities of organic matter, crude fat, crude fibre and NFE were not significantly affected by adding endo‐xylanase to the soya oil diet. However, when endo‐xylanase was included in the blended animal fat diet, digestibility of organic matter, crude fat, crude fibre and NFE were improved (P<0–05). The improvement in fat digestibility was the most pronounced, amounting to 9–4%. Nitrogen retention and metabolisable energy content were improved significantly by the addition of an endo‐xylanase to the animal fat diet (P< 0.05), by 6.6% and 6.5% respectively.

5. From the results of this study, it can be concluded that the effects on chick performance and nutrient digestibility of a dietary endo‐xylanase in a wheat‐ and rye‐based diet are influenced to a considerable degree by the type of fat in the diet.     

Metabolic and anatomical adaptations of light‐bodied chicks to intermittent feeding

1. Chicks of a light‐bodied strain were deprived of food on alternate days from 15 to 46 d of age.

2. Hyperphagia, amounting to twice the intake of control birds early in the experiment, occurred on the repletion day.

3. Final body weight attained 80% of that of the controls.

4. Body fat concentration decreased at first but returned to that of controls after 3 weeks.

5. A consistent hyperlipaemia was observed after food deprivation or restoration.

6. There was a marked increase in the digestive enzymes found in the small intestine, but not in the pancreas during the repletion day.

7. These responses may be considered as mechanisms to reduce the physiological manifestations of starvation.     

Contribution to the aetiology of synovitis in chickens,with special reference to non‐infective factors. IV

Summary

The comparative study reported in the present paper was undertaken to collect data on the collagen content and collagen quality of tendons showing high (low) tensile strength levels and a compact (loose) histological structure. It was shown that tendon tissues of these two groups do not differ in this regard. The effect of administering a number of nutrients (known to be essential in collagenesis) was tested during this study. Administration of these nutrients did not prevent synovitis and did not increase tensile strength.     

Contribution to the aetiology of synovitis in chickens,with special reference to non‐infective factors. V

Summary

A comparative study was undertaken regarding the extractability of glucosaminoglycans and mucoproteins in the tendon tissue of birds highly susceptible to synovitis, viz. broiler breed cocks (BB cocks), and of birds highly resistant to synovitis, viz. White Leghorn hens (WL hens).

It .was shown that in the case of WL hens this extractability decreased in accordance with ageing. In the case of BB cocks such a decrease was not observed. This observation is in support of a working hypothesis which supposes a relatively high degree of interaction between the several components of tendon tissue (e.g. collagen and glucosaminoglycans/mucoproteins) in the case of WL hens, and a relatively low degree of this interaction in the case of BB cocks.

Moreover the results of this study account for the observation that the tendon tissue of WL hens is more resistant to tensile stress than that of BB cocks, and they indicate that the above interaction is a determinant in the aetiology of synovitis.     

Discrepancies in Identification of Left Atrial Enlargement Using Left Atrial Volume versus Left Atrial‐to‐Aortic Root Ratio in Dogs

Background

Left atrial size is prognostically important in dogs with myxomatous mitral valve disease (MMVD).

Hypothesis/Objectives

To compare the level of agreement in identification of left atrial enlargement (LAE) between the left atrial‐to‐aortic root ratio (LA : Ao) and left atrial volume using the biplane area‐length method indexed to body weight (LA Vol/BW).

Animals

Sixty dogs with MMVD and 22 normal dogs were prospectively studied with 2‐dimensional echocardiography.

Methods

The upper limit of normal for LA Vol/BW was defined as 1.1 mL/kg. LA : Ao was deemed normal if ≤1.5. To define overall disease severity, each dog was assigned a mitral regurgitation severity score (MRSS) based on echocardiographic parameters that did not include left atrial size. ACVIM staging also was utilized.

Results

Of 60 affected dogs, 20 were ACVIM Stage B1, 25 were Stage B2, and 15 were Stage C. LA Vol/BW identified LAE in 12 cases in which LA : Ao was normal; 7 of these were Stage B1 and 5 were Stage B2. This diagnostic disagreement was significant (P = .00012). Of the 12 cases in which diagnostic discrepancies were identified, 5/5 of the B2 dogs and 3/7 B1 dogs had a moderate MRSS, whereas 4/7 B1 dogs had a mild MRSS. No diagnostic discrepancies between LA : Ao and LA Vol/BW were apparent in dogs with a severe MRSS.

Conclusions and Clinical Importance

This study shows evidence of diagnostic disagreement between LA : Ao and LA Vol/BW for assessment of LAE. LA Vol/BW may be superior to LA : Ao for identification of mild LAE.     

The egg‐laying response of the domestic hen to variation in dietary calcium

1. Eight diets (1 to 8) containing respectively 36.8, 30.9, 19.6, 9.7, 5.5, 1.9, 0.96 and 0.48 g of calcium/kg food were each fed for 11 weeks to 24 individually‐caged laying hens (Gallus domesticus) aged 24 weeks. After the experimental period, all birds were returned to a normal diet (34.9 g calcium/kg).

2. Food consumption and egg production decreased as dietary calcium decreased. Shell weight was unaffected on diets 1 and 2; on diet 3 there was slight reduction of shell weight and on diets 4 to 8 the reduction was marked. The proportion of calcium in the shell was affected particularly on diets 7 and 8, though those from diet 5 also showed a decreased shell calcium.

3. The values for calcium intake and calcium loss in the egg showed that, generally, birds restricted calcium loss to less than intake. Only on the very low concentrations of calcium (diets 6, 7 and 8) did output appear to exceed input.

4. The main mechanism for controlling calcium loss involves the regulation of the number of eggs produced, i.e. the number of ovulations. Alterations in shell quality are of less importance with respect to calcium balance, although shell strength was impaired on the more restrictive diets (5 to 8).