|Matteri, Robert - Bob|
Submitted to: Journal of Animal Science Supplement
Publication Type: Abstract Only
Publication Acceptance Date: 7/26/1996
Publication Date: N/A
Citation: Interpretive Summary:
Technical Abstract: Studies have shown that recombinant bovine placental lactogen (rBPL) improves adult rat growth performance in heat-challenge conditions. The present study was conducted to determine if similar improvement occurs during rapid prepubertal development. Sprague-Dawley female rats (50 d of age) were maintained in either thermoneutral (TN; 21 deg C) or heat-challenge (HC; 31 deg C) environments for 7 d, followed by daily ip injection of either rBPL (20 mg/day/kg BW) or sterile water for a 10-day period. Body weight and food consumption were recorded daily, with measurements of resting metabolic rate and body temperatures on the last injection day. Determinations of fat free mass (FFM), total body water (TBW), and mass of selected organs were made one day later. Change in body weight from pre-injection level was not altered by rBPL treatment in HC rats, but was increased 3.5 - 4.5 g above control level in TN rats by d 8 and 9 of injection (P<.02). Average daily gain was not altered in either environment by rBPL. Likewise, daily food intake, FFM, and TBW relative to body mass were not affected by rBPL. Relative food intake was lower, however, in HC compared to TN rats. Organ masses relative to body mass for liver, gastrointestinal tract, and kidneys were less in HC than in TN rats (P<.001-.03). However, there was no effect of rBPL treatment on relative organ weight. Metabolic rate decreased (P<.01) and tail-skin temperature increased (P<.0001) with an increase in test ambient temperature from 21 to 31 deg C, but were not affected by rBPL treatment. Although rBPL rapidly increased growth in adult rats at different ambient temperatures, it was only slightly effective in prepubertal rats. This suggests that there is an age-dependent difference in response to rBPL for this species.