Response of dairy cows to high doses of a sustained-release bovine somatotropin administered during two lactations. 1. Production response.

This study evaluated the effect of sometribove (zinc methionyl bST) in a sustained-release formulation administered to lactating cows at concentrations up to 3.0 g every 14 d over two lactations. Eighty-two lactating Holstein cows in their first, second, or third lactation were assigned to the study. Cows received .6, 1.8, or 3.0 g of bST in one, three, or five intramuscular injections of a unit dose (.6 g) every 2 wk. Controls received five injections of the vehicle (equivalent volume to the 3.0-g treatment) every 2 wk. Injections were administered from 60 +/- 3 d postpartum until dry-off or necropsy. Thirty-eight animals were continued on treatment for a second consecutive lactation. During the 1st yr of treatment, bST increased mean 3.5% FCM by 7.2, 9.4, and 8.4 kg/d over control production (21.1 kg/d). During the 2nd yr, milk response to .6, 1.8, and 3.0 g of bST averaged 10.6, 3.6, and 4.9 kg/d over controls (24.8 kg/d). The incidence of clinical mastitis increased in the 3.0-g group relative to controls during the 2nd yr. Thus, salable FCM averaged 8.1, 9.1, and 6.2 kg/d above controls (yr 1) and 12.1, 4.7, and -2.8 kg/d (yr 2) for the .6-, 1.8-, and 3.0-g groups. Salable FCM was unaffected by mastitis at a proposed commercial dose (.6 g). Milk fat, protein, lactose, calcium, phosphorus, zinc, magnesium, and ash concentrations were unaffected by bST treatment. Calculated energy, calcium, phosphorus, and protein balances also were unaffected except for early decreases of up to 5 Mcal/d, and 40, 20, and 600 g/d, respectively, until feed intake increased. Milk serum bST concentrations greater than the assay limit of sensitivity (1 ng/ml) were routinely measurable only at doses of 1.8 and 3.0 g. Results confirmed that bST concentrations in milk serum are exceedingly small. Overall, supraphysiological doses of sometribove increased milk production with little effect on composition. No toxic effects of bST were observed.

Scanning and angiography in the diagnosis of pulmonary embolism.

Lung scanning is a safe and simple procedure which, when correlated with chest roentgenograms and clinical picture, is a valuable tool in diagnosing pulmonary embolism. Pulmonary arteriography is a valuable diagnostic procedure and should be employed when serious doubt exists as to the presence or absence of pulmonary emboli. It should also be used whenever surgical treatment is under consideration.