Influence of limestone level in high concentrate and high roughage diets on site and extent of digestion in lambs.

Two digestion and slaughter trials were conducted to evaluate the influence of limestone level on site and extent of digestion and rumen fermentation in lambs. In trial 1, 11 wether lambs (avg wt 40.7 kg) were fed 75% concentrate diets supplemented with .6, 1.5 or 3.0% limestone (.6,1.2,1.7% dietary Ca, respectively) in a completely randomized design. Dry matter intake increased linearly (P less than .10) with limestone level; therefore, other data were analyzed with dry matter intake as a covariate. Total tract organic matter digestion decreased linearly (P less than .05) with increasing limestone but dry matter and fiber digestion were not affected by limestone. Ruminal digestion of dry matter and organic matter declined linearly (P less than .05) with increasing limestone. Ruminal neutral detergent fiber (NDF) digestion was higher with the 1.5 than the .6 and 3.0% limestone diets (quadratic effect, P less than .05) but ruminal digestion of other fiber components was not affected by limestone. Ruminal volatile fatty acids were not affected by limestone level; however, rumen ammonia concentrations decreased linearly (P less than .05) with increasing limestone level. In trial 2, 12 wether lambs (avg wt 43.3 kg) were fed a 35% concentrate diet with .1, 1.5 or 3.0% limestone (.5, 1.2 and 1.6% dietary Ca, respectively) in a completely randomized design. Dry matter intake was not affected by limestone level, but digestibility of dry matter, organic matter and starch (P less than .10), energy, crude protein, acid detergent fiber (ADF) and cellulose (P less than .05) responded quadratically to limestone level, with increases at the 1.5% limestone level. Ruminal dry and organic matter (P less than .05), NDF (P less than .10), ADF (P less than .01), cellulose (P less than .05) and starch (P less than .05) digestion responded quadratically to limestone level with higher values at the 1.5% limestone level. Proportions of ruminal propionate increased linearly (P less than .01) with increasing limestone level and acetate: propionate ratio declined linearly (P less than .01) with limestone level.

Millet and alfalfa hays alone and in combination with high-energy diet for receiving stressed calves.

Calves subjected to stresses of weaning, marketing, shipping and processing ate more feed, gained more weight and gained more efficiently when fed a 75% concentrate receiving diet, alone or with free choice hay, than when fed hay alone (P less than .01). Diets with greater bulk or lower energy densities did not promote higher feed intake in these stressed calves, as would be the case in unstressed animals. No differences due to receiving diets were observed in number of calves treated, days treated per sick calf, death loss or relapses. There was a trend (P less than .1) for calves on hay diets to have fewer total sick days than those fed a 75% concentrate diet alone or with free choice hay. Feed intake, weight gains and conversion of feed to gain for calves on alfalfa hay alone were superior (P less than .05) to the corresponding measures for calves on millet hay alone. Both hays fed alone were inferior (P less than .01) to a 75% concentrate diet alone or in combination with either hay in promoting weight gains and conversion of feed to gain. Gastrointestinal tract fill estimated from apparent and predicted gains amounted to 93 and 76% of apparent gains for calves fed millet or alfalfa hay respectively, but only 58% or less for those fed diets containing the 75% concentrate milled feed. Growing lambs were in negative N balance when fed millet hay alone but retained approximately 15% of N intake when fed diets containing the 75% concentrate milled feed. N retention on alfalfa hay alone was intermediate. The data indicate net tissue growth in calves fed millet hay alone is near zero during a 28-day receiving period. No differences were noted between calves receiving grubicide as a dip and those given grubicide as a pour on.