Amino acid interactions in chick nutrition. 3. Interdependence in amino acid requirements

The quantitative nature of specific interactions between certain indispensable amino acids has been examined in a series of factorial experiments with young chicks.

It was demonstrated that when the dietary concentration of lysine was 1.10 per cent, the arginine requirement of the chick was 0.80 per cent. When the lysine concentration was raised to 1.35, 1.60 or 1.85 per cent of the diet, the arginine requirement was increased to 0.92, 1.04 and 1.15 per cent of the diet respectively. In another experiment, it was found that when due importance had been attached to the interaction between lysine and arginine, the requirements for these amino acids could be lowered to 0.94 per cent and 0.81 per cent respectively. These concentrations are considerably lower than those normally recommended for young chicks.

The interrelationship between leucine and isoleucine has also been defined in quantitative terms. At concentrations of 1.40, 2.15 or 2.90 per cent leucine, the isoleucine requirement was 0.58, 0.62 and 0.65 per cent of the diet respectively.

In a further study, a similar dependence of valine requirements upon the dietary concentration of leucine was observed: at concentrations of 1.40, 2.40 or 3.40 per cent leucine, the valine requirement was shown to be 0.77, 0.89 and 1.01 per cent respectively. The results of the experiment on the threonine‐tryptophan interaction indicated that at concentrations of 0.80, 1.30, 1.80 or 2.30 per cent threonine, the tryptophan requirement was 0.17, 0.18, 0.19 and 0.20 per cent of the diet respectively.

The results of the present study permit the general conclusion that the requirements of amino acids are interdependent.     

Equine ehrlichiosis: A comparison between E. equi and other pathogenic species of Ehrlichia

Ehrlichia equi, etiologic agent of equine ehrlichiosis, is a rickettsia which morphologically closely resembles the agents of bovine petechial fever, tick-borne fever, and canine ehrlichiosis (tropical canine pancytopenia). Natural infections of E. equi have been reported only in horses; however, the experimental host range of E. equi has been broadened to include burros, sheep, goats, dogs, cats, monkeys and baboons. Infection of primates indicates that E. equi may be a zoonotic agent. An indirect fluorescent antibody test employing E. equi-infected granulocytes as antigen has been developed and used to show that infected horses develop a prolonged antibody response to E. equi. Cell-mediated immune responses measured by the leukocyte migration inhibition test were also detected in horses recovered from acute illness. Protective immunity in horses, monkeys and baboons to reinfection is long-lasting. In contrast to the blood of dogs recovered from clinical E. canis infection, the blood of horses and dogs recovered from clinical infection with E. equi is not infectious for susceptible animals. Infection of dogs with E. equi does not provide protection against subsequent infection with E. canis.     

Circular external skeletal fixation stabilization of antebrachial and crural fractures in 25 dogs

Fracture stabilization using circular external skeletal fixation was evaluated in 14 dogs with antebrachial fractures and 11 dogs with crural fractures. Most dogs were consistently weight bearing on the stabilized limb by 3 days following surgery. Although all dogs developed minor wire/pin tract inflammation and eight dogs developed major wire/pin tract inflammation, postoperative lameness was not consistently associated with wire/pin tract complications. Fractures in 23 dogs achieved radiographic union (mean +/- standard deviation [SD], 61 +/- 21 days; median, 57 days) without additional surgery; two dogs required restabilization of their fractures with linear fixators. Twenty of the 21 owners that could be contacted felt their dog had no (n=15) or only a mild (n=5) intermittent lameness at the time of final, long-term (mean +/- SD, 37 +/- 17 months; median, 42 months) assessment.     

Gastric ulceration in an equine neonate

A 24-hour-old colt presented with clinical signs consistent with gastric ulceration. Treatment was initiated with a histamine type-2 receptor antagonist and clinical signs resolved. Gastroscopy at 16 d confirmed the presence of a gastric ulcer. Although gastric ulceration is common in foals, it is rarely reported in foals this young.