Thirty-six sows were used to study responses of milk production, milk composition, and N balance to six concentrations of dietary CP ranging from 63 to 238 g/kg (4.4 to 15.1 g of lysine/kg) during the first lactation. Sows, on average, were 149.3 kg live weight and had 26.1 mm of back fat at P1 (which is 45 mm from the midline at the level of the last rib) immediately after parturition. During lactation, all sows suckled nine pigs each and were offered up to 4,000 g of feed daily; diets contained similar balances of amino acids and similar amounts of DE (3.56 to 3.63 Mcal/kg). Nitrogen balance trials were conducted during early and late lactation and 5-d collection periods commenced on d 10 and 24 of lactation, respectively. During both periods of lactation, there were significant positive linear relationships between the level of dietary protein and milk yield and contents of fat and total solids in milk. Milk yield increased from 7.79 to 9.91 kg/d and from 7.02 to 8.90 kg/d, whereas total solids in milk increased from 199 to 225 g/kg and from 202 to 228 g/kg during early and late lactation, respectively, in response to increasing level of dietary protein from 63 to 238 g of CP/kg. A two-phase linear regression model used to describe the relationship between N balance and dietary CP level established that sows required a diet containing > or = 202 g of CP/kg or 12.8 g of lysine/kg to maximize N balances during both stages of lactation.(ABSTRACT TRUNCATED AT 250 WORDS)

Water temperature plays a key role in determining the persistence of shovelnose sturgeon Scaphirhynchus platorynchus in the wild and is a primary factor affecting growth both in the hatchery and in natural waters. We exposed juvenile shovelnose sturgeon to temperatures from 88C to 308C for 87 d to determine the effect of temperature on growth, condition, feed efficiency, and survival. Growth occurred at temperatures from 128C to 308C; the optimal temperature predicted by regression analysis was 22.48C, and the minimum temperature needed for growth was greater than 10.08C. The maximum feed efficiency predicted by regression analysis was 24.5% at 21.78C, and condition factor was highest in the 188C treatment. Mortality was significantly higher at 288C and 308C than at lower temperatures but less than 10% across the thermal regimes tested and 0% at 14-188C. Mortality was observed at and below 128C, suggesting that extended periods of low temperature may deplete energy reserves and lead to higher mortality. Rearing juvenile shovelnose sturgeon at temperatures above 248C reduced the growth rate and feed efficiency and increased mortality. Temperatures in the range 18-208C appeared to maximize the combination of condition, growth, and feed efficiency while not increasing thermal stress. This study corroborates field studies suggesting that altered temperature regimes in the upper Missouri River reduce the growth of shovelnose sturgeon. This information may help protect the thermal habitat critical to the species and guide restoration efforts by delineating temperature regime standards for regulated rivers and those affected by hydroelectric facilities and suggesting new criteria for conservation propagation.

To determine the effect of exogenous porcine somatotropin (ST) on lactation performance of sows, 24 first-litter sows were injected daily at 0800 with either 10 mg of recombinant ST or an equivalent volume of buffer between d 8 and 39 of lactation. Litter size was standardized to six (n = 2), seven (n = 8), eight (n = 6), or 10 (n = 8) pigs within each pair of sows by fostering pigs within a few days after parturition. Milk yield and composition of sows given ST was similar at all stages of lactation to that of control sows. Combining treatment data revealed that the milk yield of sows was related linearly (P < .01) to litter size and was described with the following equation: MY = 1.03 (+/- .71) + .899 (+/- .102) LS (n = 24, r2 = .78), where MY is average milk yield (kilograms/day) of sows over 4 to 7, 11 to 14, 18 to 21, 25 to 32, and 32 to 39 d of lactation and LS is number of pigs in the litter. The body temperature of sows increased (P < .05) in response to administration of ST. Plasma IGF-I and glucose were increased (P < .05) by ST, but plasma urea concentrations were lower (P < .05) in ST-treated sows. Sows treated with ST lost more backfat (P < .05) during lactation, but neither voluntary feed intake nor body weight loss was significantly (P > .05) affected by ST. These data indicate that a 10-mg daily injection of ST from d 8 to 39 of lactation alters metabolism but does not increase milk production in lactating first-litter sows.

No abstract

Determining the optimal rearing temperature for the June sucker Chasmistes liorus has been identified as a key component necessary for the design of a new June sucker hatchery and for achieving the June Sucker Recovery Implementation Program supplementation goal of 350,000 fish of 20‐cm length annually. A laboratory study was conducted to monitor the performance of June suckers reared at average temperatures of 8.3, 10.1, 12.3, 14.0, 16.1, 18.5, 20.5, 21.8, 23.9, 25.9, 27.9, and 29.7°C for 16 weeks. In this study, quadratic regression analysis was used to determine maximum condition factor and weight gain, respectively, and 22.5°C and 21.9°C were identified as the maximum water temperatures. According to this same regression analysis, the maximum feed efficiency and total length increase occurred at 21.6°C and 23.7°C, respectively, during the 16‐week study. The modified acclimated chronic exposure water temperature (50% survival for 60 d) was greater than 27.9°C. Spinal and fin deformities increased during this study in all treatments, and these malformations appear to be diet related. There was no temperature effect on deformities, but temperature did affect overall survival.

Reports from hatcheries have demonstrated that commercially available diets are inadequate for June Suckers Chasmistes liorus and suggest that fish quality can be improved through species‐specific diet optimization. To determine dietary protein and lipid levels for juvenile June Suckers, practical‐type diets were formulated with 35, 40, or 45% protein and 8, 12, or 16% lipid and tested in a 3 × 3 factorial design. Two additional diets (45% protein and 16% lipid [45:16] without dicalcium phosphate supplementation and 45:16 with 2× dicalcium phosphate) were formulated to test the necessity of dicalcium phosphate supplementation. Each diet was fed to three replicate tanks (average initial fish weight ± SD = 4.48 ± 0.24 g) of fish per treatment (85 fish/tank); only duplicate tanks were used for the nondicalcium phosphate‐supplemented treatment. Fish were reared in 80‐L tanks supplied with 4 L/min of 22°C spring water and fed 6–4% body weight (BW)/d by automated belt feeders, 6 d/week. At the end of 12 weeks of culture, tissue samples were obtained to determine nutrient partitioning. An acute temperature challenge was also conducted to investigate dietary adequacy. Significant effects of diet on growth and temperature tolerance were observed. Fish fed the diet with 45% crude protein gained more weight than did fish fed 40% or 35% crude protein, and fish fed 16% dietary lipid gained more weight than did fish fed 12% and 8% crude lipid. However, the composition of this growth indicated that fish fed the 16% lipid stored larger amounts of lipid in both the visceral cavity and the muscle. A significant negative interactive effect of dietary protein and lipid on temperature tolerance was observed at 45% crude protein and 16% lipid. Results of this study define acceptable ranges of dietary protein and lipid for juvenile June Suckers and provide culturists information to make better choices regarding appropriate diets for this species.