Influence of dietary protein, fat or amino acids on the response of weanling swine to aflatoxin B1

Two experiments were conducted using corn from clean or aflatoxin B1 (AFB1)-contaminated (182 ppb) sources. Weanling pigs (28 d) were fed one of eight dietary treatments arranged in a 2 x 2 x 2 factorial design. In Exp. 1 (192 pigs), treatments varied in corn source (clean or AFB1-contaminated), CP level (18 or 20%) and added fat (0 or 5%). At the end of the 28-d growth trials, plasma samples were obtained. An AFB1 x CP level interaction was detected (P less than .05) for growth rate (ADG), feed intake (FI) and feed/gain ratio (F/G). Feeding AFB1 reduced (P less than .05) ADG (.30 vs .37 kg/d) and FI (.57 vs .66 kg/d) and increased F/G (1.88 vs 1.78) of pigs fed 18% CP diets. Performance of pigs fed 20% CP diets was not altered by AFB1. Adding 5% fat to diets improved (P less than .05) F/G but did not improve ADG of pigs fed AFB1. There was an AFB1 x CP x fat interaction (P less than .05) for plasma cholesterol. Adding fat or increasing the CP level prevented the depression of plasma cholesterol in pigs fed AFB1. In Exp. 2 (96 pigs), all diets contained 18% CP and the treatments varied in corn source (clean or AFB1-contaminated), added L-lysine HCl (0 or .25%) and added DL-methionine (0 or .15%). Feeding AFB1 reduced (P less than .05) ADG of pigs fed the 18% CP diet (.44 vs .50 kg/d) but not of pigs fed diets supplemented with .25% lysine.(ABSTRACT TRUNCATED AT 250 WORDS)     

Immune responses of breeding chickens to trivalent oil emulsion vaccines: responses to Newcastle disease and infectious bursal disease

Bivalent Newcastle disease (ND)/infectious bursal disease (IBD) and trivalent ND/IBD/infectious bronchitis (IB) inactivated oil emulsion vaccines were prepared in the laboratory and evaluated under field conditions. Broiler breeder parent chickens previously vaccinated with live vaccines were inoculated with commercial monovalent ND and experimental bivalent or trivalent oil emulsion vaccines. The commercial vaccine induced a higher initial ND haemagglutination inhibition (HI) response than the experimental vaccines but, by 34 weeks after vaccination, the mean ND HI levels were not significantly different in any of the three flocks. All three vaccines provided sufficient ND immunity to protect against the clinical disease and egg production losses. The IBD responses of both flocks vaccinated with oil emulsion vaccine were similar to each other and only slightly lower than those flocks vaccinated with monovalent IBD oil emulsion vaccine in earlier experiments. Six weeks after vaccination, sufficient immunity was transferred to protect all the progeny against IBD challenge up to 33 days of age and some of them up to 45 days of age. Thirty-four weeks after vaccination of the parents with oil emulsion vaccine, the progeny were totally immune up to 27 days of age and some of them were immune until 37 days. Application of oil emulsion vaccines in bivalent or trivalent form did not impair the responses of the chickens to the monovalent components.     

Susceptibility of chicks to infectious bursal disease (IBD) following vaccination of their parents with live IBD vaccine.

Vaccination of parent chickens with a commercial live infectious bursal disease (IBD) vaccine under field conditions at varying ages and by different routes resulted in variable susceptibility to the disease in their chicks. There was little correlation between the methods of vaccination and the levels of immunity in the chicks. There was some evidence that levels of transferred immunity decreased with the age of the parents. Of five flocks examined, the onset of susceptibility to IBD occurred at two days of age in two flocks and about one week of age in the other three. Four flocks were completely susceptible by the 27th day, the other at 31 days. Precipitins were demonstrated at day old in 100 per cent of chicks in three flocks and in 80 per cent in the other two. The precipitins had disappeared in all flocks by 17 days of age.     

Fall panicum (Panicum dichotomiflorum) hepatotoxicosis in horses and sheep

BACKGROUND: Fourteen horses at a boarding stable in Virginia were diagnosed with hepatic disease and locally grown hay was implicated as the cause. HYPOTHESIS: Panicum dichotomiflorum, the predominant grass species in the hay, is hepatotoxic to horses. ANIMALS: Naturally occurring cases were adult horses of various breeds. Two healthy adult horses and 2 healthy adult sheep were used in feeding trials. METHODS: Blood and liver specimens collected from affected animals during the outbreak were analyzed. Some of the affected animals were treated supportively; the main intervention was hay withdrawal. Feeding trials were not blinded and no treatments were provided. Blood and liver specimens were collected and analyzed throughout the trials. RESULTS: Five affected animals were euthanized, whereas the others recovered. One research horse was euthanized for postmortem examination, and the other research animals recovered after hay withdrawal. All affected animals had evidence of hepatic disease with abnormally high aspartate aminotransferase (AST), sorbitol dehydrogenase (SDH), gamma glutamyl transferase (GGT), and alkaline phosphatase (ALP) activity. Evaluation of liver biopsy specimens disclosed mild lymphocytic and histiocytic inflammation, mild vacuolar change (hydropic degeneration), prominently clumped chromatin, and necrosis of individual hepatocytes. CONCLUSIONS AND CLINICAL IMPORTANCE: Severe hepatotoxicosis developed rapidly after Panicum hay exposure. Patchy hepatocyte necrosis was observed, implicating apoptosis as the mechanism of hepatotoxicosis. Absence of fibrosis in the research animals indicates that immediate withdrawal of Panicum hay should allow all but severely affected animals to recover from acute exposure.