Twelve cows were allotted to three 4 × 4 Latin Squares to evaluate pH, ammonium nitrogen, microbial protein production, number of protozoa in the rumen, plasma and milk urea concentration and balance of nitrogen compounds. Treatments consisted of maize silage or sugarcane with whole cottonseed, at 0, 7 or 14%. There were no differences on pH between sugarcane treatments, despite the reduction of values after the beginning of feeding. Ammonium nitrogen values were kept above 15 mg/dL after 6 hours […]

The objective of this trial was to evaluate the effect of replacing Tifton hay and corn with forage cactus (Opuntia ficus indica Mill ) on microbial protein synthesis and efficiency and N metabolism in lactating Holstein cows. Diets contained (% of DM): 0, 12.0, 25.0, 38.0, or 51.0%) of forage cactus. Five Holstein cows were randomly assigned to treatments in a 5 x 5 Latin square design. Each experimental period lasted 17 days with 10 days for diet adaptation and […]

The effects of collection days on urinary excretion of creatinine and purine derivatives (PD), absorbed purines and microbial N synthesis (Nmic) were evaluated in different categories of Nellore cattle: heifers, steers, bulls and lactating cows. Yield of Nmic estimated from spot urine samples was compared to that obtained by total urine collection. Sixteen feedlot Nellore animals were assigned to a completely randomized design in a split plot scheme with treatments (two levels of concentrate [25 or 50%] and four categories […]

Two trials were conducted to study the effects of different levels of urea or cottonseed hulls on yield of microbial protein, estimated by the urinary excretion of purine derivatives, concentration of plasma urea, and excretion of urea in steers. In the first trial, 24 crossbred castrated steers averaging 300 kg of initial live weight (LW) were uniformly assigned to four treatments in a complete randomized design as follows: 0, 0.65, 1.30, or 1.95% of urea (% of dry matter) that […]

Twelve Holstein cows were allotted to four 4 x 4 Latin square balanced in accordance with the lactation period, with the objective of evaluating the protein production, using the total purine derivatives (PD) excretion, obtained from spot urine collection, the plasma and milk urea and nitrogen(N)-urea, pH and ruminal ammonia concentration. The four experimental diets were formulated to contain 70% of corn silage and 30% of concentrate. Increasing levels of wheat middlings in the concentrate (0, 33, 67 and 100%) […]

Twelve purebred and crossbred Holstein cows were allotted to three 4 x 4 Latin Squares to evaluate the nitrogen (N) balance, microbial protein production, plasma and milk urea concentration and different urine collections times. The experimental diets were based on corn silage (CS) (AG 1051) with forage:concentrate ratio (F:C) of 60:40, in dry matter (DM) basis, or in sugar cane basis (SC) (RB 855536) with F:C of 60:40 with .35 or 1% of urea+ammonium sulfate (AS) mixture or FC of […]