Evaluation of perennial ryegrass straw as a forage source for ruminants

Two experiments were conducted to evaluate perennial ryegrass straw as a forage source for ruminants. Experiment 1 evaluated digestion and physiological variables in steers offered perennial ryegrass straw containing increasing levels of ergot alkaloid, lolitrem B. Sixteen ruminally cannulated Angus x Hereford steers (231+/-2 kg BW) were blocked by weight and assigned randomly to one of four treatments. Steers were provided perennial ryegrass straw at 120% of the previous 5-d average intake. Before straw feeding, soybean meal was provided (0.1% BW; CP basis) to meet the estimated requirement for degradable intake protein. Low (L) and high (H) lolitrem B straws (<100 and 1,550 ppb, respectively; DM basis) were used to formulate treatment diets: 100% L; 67% L:33% H; 33% L:67% H; 100% H (DM basis). Intake and digestibility of DM and OM, and ruminal pH, total VFA, and NH3-N were not affected by increasing lolitrem B concentration. Ruminal indigestible ADF (IADF) fill increased linearly (P = 0.01) and IADF passage rate decreased linearly (P = 0.04) as lolitrem B increased. Experiment 2 evaluated performance and production by 72 Angus x Hereford cows (539+/-5 kg BW) consuming perennial ryegrass straw containing increasing lolitrem B during the last third of gestation. Cows were blocked by body condition score and randomly assigned to one of three treatments. Cows were provided perennial ryegrass straw ad libitum and supplemented with soybean meal (0.1% BW; CP basis) to meet the estimated requirement for degradable intake protein. Mixtures of a L and H lolitrem B straw (467 and 2,017 ppb, respectively) were used to formulate treatment diets: 100% L, 50% L:50% H, 100% H (DM basis). Thirteen of 24 cows on the 100% H treatment exhibited signs of ryegrass staggers and were removed from the study; nevertheless, lolitrem B concentration did not influence pre- or postcalving weight or body condition score change. These data suggest that feeding perennial ryegrass straw containing up to 1,550 ppb lolitrem B (DM basis) did not adversely affect nutrient digestion or physiological response variables in steers. However, providing straw with a lolitrem B concentration of approximately 2,000 ppb (DM basis) resulted in 54% of cows exhibiting signs of ryegrass staggers. These data suggest that blending straws with a high (>2,000 ppb) and low (<500 ppb) concentration of lolitrem B can be a successful management practice.     

In vitro comparison of the use of two large-animal, centrally threaded, positive-profile transfixation pin designs in the equine third metacarpal bone

OBJECTIVE: To compare the in vitro holding power and associated microstructural damage of 2 large-animal centrally threaded positive-profile transfixation pins in the diaphysis of the equine third metacarpal bone. SAMPLE POPULATION: 25 pairs of adult equine cadaver metacarpal bones. PROCEDURE: Centrally threaded positive-profile transfixation pins of 2 different designs (ie, self-drilling, self-tapping [SDST] vs nonself-drilling, nonself-tapping [NDNT] transfixation pins) were inserted into the middiaphysis of adult equine metacarpal bones. Temperature of the hardware was measured during each step of insertion with a surface thermocouple. Bone and cortical width, transfixation pin placement, and cortical damage were assessed radiographically. Resistance to axial extraction before and after cyclic loading was measured using a material testing system. Microstructural damage caused by transfixation pin insertion was evaluated by scanning electron microscopy. RESULTS: The temperature following pin insertion was significantly higher for SDST transfixation pins. Periosteal surface cortical fractures were found in 50% of the bones with SDST transfixation pins and in none with NDNT transfixation pins. The NDNT transfixation pins were significantly more resistant to axial extraction than SDST transfixation pins. Grossly and microscopically, NDNT transfixation pins created less damage to the bone and a more consistent thread pattern. CONCLUSIONS AND CLINICAL RELEVANCE: In vitro analysis revealed that insertion of NDNT transfixation pins cause less macroscopic and microscopic damage to the bone than SDST transfixation pins. The NDNT transfixation pins have a greater pull out strength, reflecting better initial bone transfixation pin stability.     

Cardiopulmonary effects of restraint in dorsal recumbency on awake cattle

The cardiopulmonary effects of dorsal recumbency were studied in awake cows restrained for surgical correction of left displaced abomasum. During the recumbent period, PaO2, PaCO2, arterial pH, and base excess values were significantly decreased. Heart rate, respiratory rate, blood hemoglobin concentrations, and rectal temperature increased significantly.     

Exercise-induced pulmonary haemorrhage in the horses: results of a detailed clinical, post mortem and imaging study. VII. Ventilation/perfusion scintigraphy in horses with EIPH

Detailed post mortem examination of the lungs of horses with exercise-induced pulmonary haemorrhage (EIPH) has demonstrated significant small airway disease and intense bronchial arterial proliferation in the dorsocaudal lungfields. The purpose of this study was to investigate ventilation and perfusion distribution in the lungs of a similar group of horses to compare changes in the live animal with the previously reported post mortem findings. Thoracic radiography and ventilation/perfusion (V/Q) scintigraphy were performed on five racing Thoroughbreds with recent histories of EIPH. Parametric images of V/Q ratios for left and right lungfields were also generated from the scan images. In all horses, ventilation and perfusion deficits were demonstrated in the dorsocaudal areas of the lung corresponding closely to the observed radiographic lesions. In particular, the perfusion images and V/Q ratio displays indicated that, in affected areas of lung, pulmonary arterial perfusion was the more seriously impaired. This finding appears to confirm the post mortem evidence of reduced pulmonary arterial perfusion and bronchial arterial dominance in these areas. Ventilation deficits in the same areas also confirmed the likelihood of partial airway obstruction consistent with the small airway disease noted in previous post mortem observations. These results suggest that the vascular and airway lesions demonstrated in detailed post mortems of horses with EIPH are also functionally important in affected horses, even at rest. As a consequence of the apparent persistent, insidious and progressive nature of the lesions associated with EIPH there are serious long term implications for management of the condition.     

Lymphosarcoma with urinary bladder infiltration in a horse.

A 9-year-old Thoroughbred mare was examined because of pollakiuria, hematuria, and weight loss of 3 weeks' duration. Physical examination revealed a regular cardiac rhythm with occasional premature contractions, and a soft tissue mass in the pelvic canal palpable per rectum. Microscopic examination of urine sediment revealed numerous RBC and a large population of lymphocytes and lymphoblasts with characteristics of neoplasia. Similar cells were found in peritoneal fluid obtained by abdominocentesis. The horse was euthanatized without treatment. Necropsy revealed a soft tissue mass infiltrating the bladder, vagina, and uterus. Additional masses were found in the sublumbar muscles and myocardium. The histologic diagnosis was lymphosarcoma.     

A note on the mode of action of the systemic fungicide tridemorph

The effects of the systemic fungicide tridemorph on fungal and plant protoplasts have been investigated. No evidence of reaction at the plasma-membrane was revealed by microelectrophoresis. The fungicide did not affect oxygen uptake by fungal protoplasts but incorporation of labelled histidine was reduced. Fungi-toxicity tests showed that tridemorph had little effect on spore germination but inhibited mycelial growth. It is suggested that the fungicide may act by interfering with the synthesis of proteins essential for hyphal extension.     

Efficacy, safety, and residue evaluation of levamisole gel formulation in sows

Anthelmintic efficacy, safety, and residue studies were conducted in sows and gilts with a levamisole gel containing 11.5% levamisole HCl. In 12 sows and 12 gilts, 8 mg of levamisole HCl equivalent/kg of body weight orally was 100% (resinate) and 91.1% (gel) effective against 55-day-old Ascaris suum and 100% (gel) and 96.1% (resinate) effective against Oesophagostomum dentatum. In 20 sows given levamisole gel (8 mg of levamisole HCl/kg) orally just before breeding, 4 to 6 weeks after breeding, 4 to 6 weeks before farrowing, and just before farrowing, there were no adverse effects. Transient salivation was noticed in five sows after treatment. In 4 groups of 4 sows each given levamisole gel orally to provide 8, 24, 40, or 80 mg of levamisole HCl/kg, adverse clinical signs were not observed in sows treated with 8 mg/kg. Transient salivation was noticed in one sow given 24 mg/kg, two sows given 40 mg/kg, and four sows given 80 mg/kg. Multiple emesis and chomping occurred in one sow given 80 mg/kg. Levamisole residues in edible tissues from sows given 8 mg of levamisole gel/kg orally were less than 0.1 mg/kg of muscle and fat in sows killed on posttreatment day (PTD) 3 and less than 0.1 mg/kg of kidney in sows killed on PTD 5. Liver residues averaged 0.78 mg/kg in sows killed on PTD 3 and were reduced to 0.31 mg/kg in sows killed on PTD 5. The 99% upper tolerance limit with 95% confidence on the withdrawal time to assure levamisole residues of less than 0.10 mg/kg in liver tissue was 11 days.     

The arginine-lysine interaction in the chick

A series of trials with cross‐bred, day‐old chicks was carried out to check on the specificity of the arginine‐lysine interaction postulated by several workers. We have concluded that this interaction is a nonspecific manifestation of a general phenomenon of amino‐acid detoxification. Our conclusions are, in part, based on the following observations:

Amino acids other than lysine could be shown to depress growth. Isonitrogenous supplements of phenylalanine and of methio‐nine caused much more severe growth depressions than equivalent amounts of lysine. The addition of arginine plus glycine partially alleviated these depressions although much more effectively for lysine than for phenylalanine or methionine. There was no reciprocity in the arginine‐lysine interaction; i.e. excess arginine added to lysine‐deficient diets had no depressing effect.     

Effect of the amount and position of leaf tissue on the yield of single-truss tomatoes

Immediately after first anthesis, leaf removal treatments were applied, involving varying amounts of leaf tissue at different positions on the stem of widely spaced single-truss tomato plants.Yield was shown to be related to leaf dry weight, while leaf position did not appear to be important, except for those leaves closest to the roots. The leaves and roots were shown to be in competition with the reproductive tissues for dry matter.