Intestinal absorption of corn oil and beef tallow was studied in White Leghorn male chicks during the periods of 2 to 7 and 8 to 15 days of age. Absorption of both fats was less at the earlier age. The corrected absorbability of corn oil increased from 84 to 95%; that of beef tallow from 40 to 79%. With both dietary fats, the greatest amount of fat appeared in the excreta at 5 and 7 days of age and then decreased rapidly within a 2-day period. Absorbability values for corn oil and tallow during the 8 to 15 day period agreed with generally accepted values found in the literature, while those for the 2 to 7 day period were lower. These results show that the newly hatched chick does not have full physiological capacity for fat absorption. However, this appears to develop rapidly after the first few days of life.

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The Pima cotton (Gossypium barbadense L.) plant is inherently late maturing and unsuitable for production in areas where highly probable late‐season rainfall coincides with boll opening. A field study was conducted between 1990 and 1992 to determine if the maturity of Pima cotton can be enhanced with applied N and P without reducing lint yield. Five preplant‐applied N rates up to 180 kg ha−1 in 1990 and up to 269 kg ha−1 in 1991 and 1992 were tested. Four P rates from 0 to 45 kg ha−1 in a factorial combination with N were tested in 1991 and 1992. Nitrogen did not affect yield, days to first flower, or estimated percent open bolls in 1990. Nitrogen deficiency significantly enhanced maturity in 1991 and 1992. In 1991, >70% of the total bolls opened by 153 days after planting (DAP) where no N was applied, compared with 178 DAP where 202 or 269 kg N ha−1 was applied. In 1992, 68% of the bolls in the 0 kg N ha−1 treatment opened by 142 DAP, compared with <55% for all other treatments. The 0 kg N ha−1 treatment also significantly increased the ratio of reproductive to total plant dry weight earlier during the boll development period; however, the maturity‐enhancing effect of N deficiency occurred at the expense of lint yield. Relative to the 67 kg N ha−1 treatment, zero N reduced lint yield by 277 kg ha−1 (26%) in 1991 and 214 kg ha−1 (18%) in 1992. Phosphorus deficiency reduced lint yield in 1991, but did not affect percent open bolls or reproductive efficiency in 1991 and 1992. Earliness of Pima cotton may, therefore, be managed more effectively by minimizing applied N rates than by manipulating P fertilization.

Broiler chicks from 2 to 4 weeks of age were fed control (0.23%) and deficient (0.115, 0.058%) levels of L-tryptophan. Separate groups of control chicks were pair-fed daily with the deficient chicks. Deficient chicks grew less efficiently than did pair-fed controls. Plasma triiodothyronine (T3) was elevated in deficient chicks, especially compared to pair-fed controls, and this was accompanied by lower reverse T3. Plasma thyroxine (T4) was also reduced with 0.059% tryptophan. However, thyroid weights and follicle diameters were unchanged. Reductions in weight gain and bone growth, increases in pituitary and pineal weights, and elevations in plasma GH occurred in the tryptophan-deficient chicks apart from any effect due to reductions in feed intake. Comb and testis size, and plasma testosterone were little affected by the deficiency. Based on changes in plasma T3 levels and feed conversion efficiencies, we conclude that tryptophan-deficient chicks show signs of relative hyperthyroidism and energy wastage compared to pair-fed controls. The elevations in plasma growth hormone and T3 support the concept that serotonin is a negative modulator of the synthesis or release of these hormones in chickens.

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