The purpose of this study was to evaluate the impact of polymer-coated urea on nitrogen retention, rumen microbial growth, and milk production and composition. Coated urea (CU) that is more slowly hydrolyzed to ammonia than unprotected urea could potentially be used more efficiently by rumen microorganisms. Eight cows were offered each of three diets in a randomized crossover design. Each treatment period consisted of a 14-d adjustment period and a 5-d collection period. Diets were formulated to maintain milk production while reducing plasma urea nitrogen concentrations and urinary nitrogen excretion. Diets consisted of corn silage, mixed grass/legume haylage, chopped alfalfa hay, corn meal, protein, vitamin and mineral supplements, in a total mixed ration and fed ad libitum. The diets contained 17.9%, 18.1%, and 16.4% CP and 0, 0.77%, and 0.77% CU (dry matter basis) and are denoted as CP18-CU, CP18+CU, and CP16+CU, respectively. Individual feed intakes were measured, and total fecal, and urine collections were conducted. Cows were milked twice daily at 0500 and 1700 h, and the milk sampled for composition and milk urea N analysis. Dry matter intake averaged 23.5 +/- 0.2 kg/d and was not altered by diet. Also, milk fat and true protein were not altered by diet and averaged 3.72 and 3.07%, respectively. Milk yield was highest for diets CP18-CU and CP18+CU. Significant differences were observed in N intake and excretion in urine, feces, and milk between dietary treatments. Cows fed CP16+CU consumed 11% less N than in CP18-CU. Cows fed CP18+CU showed the highest excretion of N in urine, and together with CP16+CU, the lowest N excretion in feces. Nitrogen excretion in milk was lower for cows fed CP16+CU. Calculated N balance was not significantly different between diets nor was it significantly different from zero. Efficiency of N capture in milk protein as a function of N intake was higher for animals on CP16+CU. Urinary excretion of purine derivatives was not different between diets, and estimated microbial CP was also similar. Coated urea was not effective at reducing nitrogen excretion by dairy cattle.

Betaine is a natural compound found in sugar beets that serves as a methyl donor and organic osmolyte when fed to animals. The objective was to evaluate the effect of feeding betaine-containing molasses on performance of transition dairy cows during late summer in 2 trials. In early September, cows were randomly assigned to betaine (BET) or control (CON) groups either shortly after dry off (trial 1; n = 10 per treatment) or 24 d before calving (trial 2; n = 8 per treatment) based on parity and previous mature equivalent milk yield. Cows were fed common diets supplemented either with a liquid supplement made of molasses from sugar cane and condensed beet solubles containing betaine [BET, 89.1 g/kg of dry matter (DM)] or a sugar cane molasses-based liquid supplement without betaine (CON) until 8 wk postpartum. The liquid supplements had similar nutrient contents and were fed at a rate of 1.1 and 1.4 kg DM/d for pre- and postpartum cows, respectively. Starting at their entry in the studies, cows were housed in the same freestall barn without a cooling system. After calving, all cows were housed in the same barn cooled by misters and fans and milked thrice daily. Intake was recorded daily and body weight and body condition score were assessed every 2 wk. Milk yield was recorded at each milking and composition was analyzed weekly. Blood samples were collected weekly from a subset of cows to assess concentrations of metabolites and AA. No treatment effects were apparent for DM intake and body weight in the prepartum and postpartum periods. For cows enrolled at dry off, BET supported higher milk yield (45.1 vs. 41.9 kg/d) and fat content (4.78 vs. 4.34%) and elevated plasma concentrations of nonesterified fatty acids and β-hydroxybutyrate in early lactation compared to CON. However, no differences were observed for milk yield, most milk component contents and yields, and blood metabolites between treatments for cows enrolled during the close-up period. Compared to cows in the CON group, BET cows enrolled during the far-off period tended to have lower plasma concentrations of Met, Thr, and Trp during the pre- and postpartum periods. They also had lower plasma concentrations of Lys and Phe before calving but higher plasma Gly concentration after parturition. In conclusion, feeding a betaine-containing liquid supplement from far-off through early lactation improves lactation performance but increases adipose tissue mobilization and production of ketone bodies in early lactation.

Thirty-six 5-month-old Dorset ram lambs (28·7 kg) were used to investigate the effects of fasting and transport on performance and selected blood parameters. Three treatment groups (no. = 12) were: (1) control-food and water, without transport; (2) fasting for 72 h, without transport; and (3) transport in a trailer to a nearby auction-barn, then driven 8 h/day for 3 days without food or water for a total of 72 h. Lambs were given a total mixed diet containing 163 g/kg crude protein throughout the 28-day post-transport period. Both fasted and transported lambs consumed less food than the control group during the first 7 days post treatment (P < 0·05). Water intake was similar for all treatment groups on the 1st day post transport, after which both fasted and transport lambs drank less ivater than control lambs during the following 6 days (P < 0·05). Live-weight loss after the 3-day fast and transport period and subsequent body-weight gain during the 28-day realimentation period differed across all treatment groups (P < 0·05 and P < 0·09; (1) 1% and 305 g, (2) 14·8% and 343 g, and (3) 20·0% and 390 g, respectively, though control lambs had the highest weight gains over the 32-day experimental period. Plasma urea nitrogen was lower in both fasted and transported lambs on days 6, 7 and 11 compared with control lambs (P < 0·05). Plasma glucose concentrations on days 4 and 5 were lower in transported lambs than in fasted lambs, and highest in control lambs (P < 0·05); glucose concentration levels remained lower in both fasted and transported lambs than in control lambs on days 6 and 7 (P < 0·05). Plasma cortisol concentrations were highest in transported lambs during the 3-day transport period and for 2 days immediately following transport (P < 0·05). Effects of the 72 h fast were exacerbated by auction barn activity and subsequent transport, and compensatory gains by fasted and transport lambs were incomplete within the 28-day post transport period.

An in vitro technique and an in situ technique were used to measure release of Ca, Mg, P and Zn over time from hand-clipped alfalfa (Medicago sativa L.). Maximal release of P and Zn was greater using the in situ technique. 'Florida 77' alfalfa (Medicago sativa L.), 'Florigraze' rhizoma peanut (Arachis glabrata Benth.), 'Mott' dwarf elephantgrass (Pennisetum purpureum Schum.), 'Tifton 78' bermudagrass (Cynodon dactylon (L) Pers.), 'Pensacola' bahiagrass (Paspalum notatum Flugge) and 'Floralta' limpograss (Hemarthria altissima (Poir.) Stapf and Hubbard) were used to examine the ruminal release of Ca, Mg, P, K, Cu and Zn by means of the in situ technique. Minerals were ranked from highest to lowest for extent of immediate and maximal release in the rumen. Averaged across forage species, ranking was K at 100% and 100%, Mg at 82% and 95%, Cu at 71% and 84%, P at 66% and 80%, Zn at 26% and 69% and Ca at 29% and 70%. A large proportion of Ca was associated with the plant cell wall, based on the duration of incubation time needed to maximize its release and the large fractinal amount of Ca slowly released. A large portion of the Zn was released slowly as well (mean, 43.8%), but release of Zn was maximal in less than 24 h. Most of the Mg, K, P and Cu probably reside in the cell contents. Forages with high NDF concentrations can have high release coefficients for their minerals.

A study was conducted to measure the extent of DM disappearance and mineral release from six forage species within the rumen, abomasum and intestines of the adult bovine using the mobile bag technique. Three nonlactating Holstein cows, fitted with ruminal and duodenal cannulas, were given ad libitum access to alfalfa hay. One gram (DM) of alfalfa, rhizoma peanut, dwarf elephantgrass, bahiagrass, bermudagrass, and limpograss was individually weighed into 8-cm x 3-cm dacron bags. After ruminal incubation for 24 h, bags were incubated in an acid-pepsin solution (a simulated abomasal environment) for 1 h, inserted into the duodenum via cannula, and collected in the feces upon excretion. Ruminal incubation accounted for 86% to 100% of total DM disappearance. Release of Ca from all forages was at least 65%, with the majority having extents of release of over 70%. Most Ca was released in the rumen, but acid-pepsin incubation and washing increased Ca release an additional 17 to 272%. Forages with the highest NDF concentration (bermuda, bahia, and limpograss) sequestered Ca in the intestines. Total tract P release ranged from 84 to 98%, with an average of 7.5 percentage units occurring postabomasally. Grasses released more P in the intestines than legumes. Eighty-eight to 98% of total Mg was released in the rumen. Acid-pepsin incubation increased Mg release only slightly, with some Mg being sequestered in the intestines. Potassium release was complete in the rumen. Ranking of minerals based on maximal extent of release was K greater than Mg greater than P greater than Ca. With the exception of K, legumes released more of their minerals than grasses.