Effect of method of applying fibrolytic enzymes or ammonia to Bermudagrass hay on feed intake, digestion, and growth of beef steers.

This study examined how different methods of applying a fibrolytic enzyme or ammonia affect the nutritive value of Bermudagrass hay and the performance of beef cattle. Fifty Angus x Brangus crossbred steers (mean initial BW 244 +/- 26 kg) were individually fed for ad libitum intake of a 5-wk regrowth of a mixture of Florakirk and Tifton 44 Bermudagrass [Cynodon dactylon (L.) Pers] hay for 84 d with a concentrate supplement (77% soybean hull pellets, 23% cottonseed meal (DM basis) fed at 1% of BW daily. The Bermudagrass was conserved as hay without treatment (control), with NH(3) (30 g/kg of DM), or with a fibrolytic enzyme (16.5 g/t, air-dry basis) that was applied immediately after cutting (Ec), at baling (Eb), or at feeding. Chromic oxide was dosed to steers for 10 consecutive days, and fecal Cr concentrations from the last 5 d were used to estimate apparent total tract digestibility. In situ ruminal DM degradability was measured by incubating ground (4-mm) hay samples in duplicate in each of 2 ruminally cannulated cows having ad libitum access to Bermudagrass hay and 500 g/d of soybean meal. Unlike the enzyme treatment, ammoniation increased (P < 0.001) the CP concentration and reduced (P < 0.001) NDF, hemicellulose, and lignin concentrations of hay. Total DMI was greater (P < 0.05) for steers fed hays treated with Ec or NH(3) than for those fed control hays. All additive treatments increased (P < 0.05) DM digestibility, and NH(3), Ec, and Eb treatments also increased (P < 0.01) NDF digestibility. The initial and final BW, ADG, BCS, G:F, and hip height of the steers were not affected (P > 0.05) by treatment. The wash loss fractions in hays treated with Ec and Eb were lower than that in the control hay, but the potentially degradable fraction, total degradable fraction, and the effective degradability were increased (P < 0.01) by NH(3) treatment. Application at cutting was the most promising method of enzyme treatment, and this treatment was almost as effective as ammonia for enhancing forage quality.

Cortisol and vagal tone responses to competitive challenge in preschoolers: associations with temperament.

Sixty-one 3- to 5-year-old nursery school children participated in a study of tempera ment and stress responses to competition. Each child individually participated in a competition against a familiar adult experimenter to determine who would win enough games to receive a prize. After initially winning three games (Win Period), the children lost the next three games (Lose Period), before winning the final games and receiving the prize. Salivary cortisol, vagal tone, affect and turn-taking behavior were measured in response to the competition and examined in relation to child temperament using a teacher-report version of the Child Behavior Questionnaire. Behavioral measures indicated that the procedures were emotionally engaging and the threat of losing was aversive. Surgency (extroversion) was positively correlated with positive affect during Win periods and tense/angry affect during the Lose period of the competition. Vagal tone decreased as the children began to play against the adult and children who were more tense/angry while losing showed additional suppression of vagal tone when they began to lose the competition. Most of the children did not show a cortisol response to the competition; however, the 15% who increased cortisol (responses >1 SD of classroom baselines) were described by teachers as more surgent and lower in effortful control. All but one of these children who increased in cortisol was male. Cortisol responsive children also displayed higher levels of tense/angry affect during the Lose period. Surgent, extroverted children appear to be vulnerable to competition stress.

The start of a new school year: individual differences in salivary cortisol response in relation to child temperament.

Noon and evening salivary cortisol levels were examined in 70 elementary school children during the 1st week of a new school year. Samples were obtained on the 1st and 5th days of school and on weekend days. Delta cortisol scores were created to measure the change in children's levels on initial school days relative to weekend days. Temperament was assessed using Rothbart's Child Behavior Questionnaire, a parent report instrument. The three dimensions of surgency or extroversion, negative affectivity, and effortful control were examined. Positive correlations were obtained with Day 1 delta cortisol for negative affectivity and Day 5 delta cortisol for surgency. Contrary to the expectation that internalizing aspects of temperament (shyness, fearfulness) would be associated with larger increases in cortisol to the novelty and challenge of a new school year, these data indicate that larger increases in cortisol were observed in more extroverted children.