1. The transferrin types of 225 Jersey cows in thirteen herds, and 433 Australian Illawarra Shorthorn cows in twenty-four herds in Queensland were determined. The effect of transferrin type on lactation length, milk yield, butterfat yield and butterfat percentage was assessed by a leastsquares multiple linear regression analysis.2. The results for the two breeds did not differ significantly. Combining the data from both breeds, it was found that on average D/D cows had lactations 13·9 days longer than A/A cows (P < 0·01), and yielded 449·7 lb. more mills (P < 0·01). The results for A/D cows were intermediate.
Rectal temperatures of 934 Jersey and Australian Illawarra Shorthorn dairy cows were recorded during summer months im¬ mediately before artificial insemination. They ranged from 98-8°F to 105-0°F (mean 101-6 ± 0-9°F) and were related directly to stage of oestrus, supporting an earlier report of a thermal response at oestrus. Thus, the temperature of the cow's genitalia may be high during oestrus; and the sperms may be subjected to such environment for several hours after insemination. In addition, the data support the hypothesis that the normal diurnal rhythm of body temperature is restored some hours before ovulation occurs. Under such conditions, high rectal temperatures at the time of insemination were not inimical to the subsequent fertilization process. Indeed, in one group of cows, inseminated at a late stage of oestrus, fertility was better (P<0-05) in cows with elevated temperatures than in those with low values.
Equipment has been developed to facilitate measurement of the acoustic target strengths of single penaeid prawns arranged at various orientations to the insonifying beam direction. The dorsal plane target strengths of several species of penaeid prawns in the length range 16�2 cm and for frequencies in the range 50-1200 kHz are described by:
Ts=-44.4-2.52 × 10-3f
for the maximum target strength values observed, and
Ts = -51.2-1.68 × 10-3f
for values of target strength averaged over the dorsal plane. Ts values are in dB ref. 1 m and f, the insonifying frequency, is in kHz.
Target strength values averaged over the central �40� of the dorsal plane were essentially constant with frequency, at a value of approximately - 47 dB ref. 1 m.
For the target lengths and sound frequencies used the amplitude of the backscattered pressure signal varies rapidly with changes in target orientation and an ensemble of such amplitudes, measured at 200 kHz in the dorsal plane, is shown to be distributed approximately according to the Rayleigh distribution function.
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