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The objective of the trial was to determine if supplementing a low-K prepartum diet (

Three hundred lactating Holstein cows were used in a 3 × 3 Latin square trial to determine the impact of feeding whole cottonseed with different concentrations of free fatty acids (FFA) in the oil. Treatments included whole cottonseed with low (10.7% FFA, LO), high (35.5% FFA, HI) or a 50:50 blend of LO and HI (23.1% FFA, MED). Whole cottonseed provided 8.5% of the total dietary DM in the experimental diets, which were fed to each pen of 100 cows. Cows were assigned to each pen by parity, days in milk, and milk yield. The DMI and milk yield were similar for all treatments and averaged 27.5 and 39.9 kg/d, respectively. Milk fat percentage and yield were lower for cows fed diets containing HI (2.87% and 1.14 kg/d) compared with LO (3.02% and 1.21 kg/d) and MED (3.13% and 1.26 kg/d). No differences were observed in percentage or yield of milk protein among treatments, which averaged 2.97% and 1.18 kg/d, respectively. Yield of energy corrected milk was lowest for HI, reflecting the reduced yield of milk fat. Concentrations of milk urea N were lower for LO compared with HI. Results of this trial indicated that feeding whole cottonseed with elevated FFA does not negatively impact DMI or milk yield of lactating dairy cows although reduced milk fat percentage and increased milk urea N concentrations are possible.

Cherney, D.J.R., Cherney, J.H. and Siciliano-Jones, J. 1995. Alfalfa composition and in sacco fiber and protein disappearance as influenced by nitrogen application. J. Appl. Anim. Res. 8:105–119. Nitrogen (0, 112, 224, 336 kg of N as ammonium nitrate/ha) was applied to field plots of established alfalfa (Medicago sativa L.) to evaluate its effect on forage quality. Two first-growth cuttings (bud stage; 1 wk apart) were harvested beginning in May. Alfalfa fertilized with 336 kg N/ha had slightly lower neutral detergent fiber (NDF) than alfalfa fertilized with 0 kg N/ha (32% vs. 33% NDF). Nitrate, crude protein, soluble crude protein (dry matter basis) and crude protein solubility increased with increased N fertilization. As expected, the later cutting of alfalfa was higher in NDF and lignin and lower in nitrate and crude protein (CP). In another study, alfalfa was ruminally incubated in nylon bags to determine the influence of N fertilization, harvest date and level of fat in cow diet on dry matte...

Objectives of this study were to determine the influence of five donor cow diets that differed in source of fiber on true in vitro DM digestibility of eight forages. Test forages included two alfalfa (31.2 and 38.3% NDF), corn silage (50.2% NDF), oat forage (48.2% NDF), perennial rye (62.1% NDF), two reed canarygrasses (55.9 and 68.1% NDF), and timothy (68.2% NDF). Sources of fiber in donor cow diets were alfalfa haylage or alfalfa haylage plus either corn cobs, cottonseed hulls, oat hulls, or soy hulls. In addition, the effect of filtering through sintered glass crucibles or filter paper (two replicates each) was evaluated. There were differences (P.01) among feeds in in vitro DM digestibility, but there were no interactions (P.05) between test forages and either source of fiber in donor diets or filtration method. There was an interaction between source of fiber in the donor diet and method of filtration (P.01). Samples inoculated with ruminal fluid from cows fed diets with oat hulls or soy hulls had lower (P.01) in vitro DM digestibility when filtered on crucibles than on filter paper. Filtration method did not affect (P.05) in vitro DM digestibility of samples inoculated with ruminal fluid from other diets. The in vitro DM digestibility of samples inoculated with ruminal fluid from cows fed alfalfa haylage was less than the in vitro DM digestibility when other inocula were used. The source of fiber in the donor cow diet and filtration method can affect in vitro DM digestibility, but relative ranking of forages was unaffected by these variables.

Experiments were designed to compare true and functional specific gravity of feed particles and to study the effects of particle size and in vitro fermentation on functional specific gravity. True specific gravity was estimated by centrifuging size fractions of various feedstuffs in ethanol-carbon tetrachloride density gradients. Functional specific gravity was determined in pycnometers. True specific gravity ranged from 1.3 to 1.5 but did not consistently differ with feedstuff or particle size. In contrast, functional specific gravity was affected by feedstuff, particle size (for forages), and in vitro fermentation. Functional specific gravity increased as forage particle size decreased and, for different forages, changed similarly over the in vitro fermentation period. A significant forage by particle size interaction suggested that differences in functional specific gravity between forages were not maintained as particle size changed. Part of the reduction in ruminal retention time achieved by decreasing the particle size of a feedstuff may result from its effects on functional specific gravity. Manipulating the diet to alter the functional specific gravity of particles in the rumen may help to obtain the desired effects on digestion in and passage from the rumen.

We tested the effects of substituting a whey protein concentrate for dam's colostrum at first feeding and of 1% brewer's yeast in dry feed on calf health and performance. Eighty-four calves were assigned to four preweaning and eight postweaning treatments based on feeding either dam's colostrum or a whey protein concentrate at birth and either yeast or no yeast in the dry feed both before and after weaning. After the first feeding, all calves were fed colostrum through 4 d of age and an all milk protein milk replacer from d 5 to 46 of age. Daily feed intakes, health measurements, and weekly BW were recorded. Calves fed whey protein concentrate at birth had similar health parameters and greater feed efficiency than calves fed colostrum over the preweaning period. Addition of 1% brewer's yeast to the dry feed apparently reduced the incidence of fever and the number of associated antibiotic treatments during the preweaning period, but had no effects thereafter. Under the conditions of this study, whey protein concentrate was an effective substitute for dam's colostrum at first feeding, and 1% brewer's yeast fed in dry feed may reduce susceptibility to infection prior to weaning.

Digestion in the large intestine was investigated in four growing steers fitted with duodenal and ileal cannulas. Diets assigned within a 4×4 Latin square were: 20% long alfalfa hay and 80% grain; 15% pelleted alfalfa, 5% hay, and 80% grain; 80% hay and 20% grain; and 60% pellets, 20% hay, and 20% grain. Intake of DM was not affected by diet. Organic matter digestion in the large intestine averaged 9, 3, 1, and −4% of total tract digestion for the 20% hay, 20% pellet, 80% hay, and 80% pellet diets, respectively, with significant increases due to high grain diets and long hay. Digestion of CP in the large intestine as a percentage of total tract digestion was unaffected by diet but averaged 3, −1, .3, and −6% for the respective diets. Percentage of total tract starch digestion occurring in the large intestine increased with grain feeding and averaged 6, 3, 1, and 1%, respectively. Digestion of ADF and NDF in the large intestine as a percentage of total tract was unaffected by diet; however, the respective means were 16 and 15, 7 and 7, 5 and 15, and 1 and 1%. In a second trial the same animals were fed a more typical dairy cow diet consisting of 50% grain, 25% corn silage, and 25% long alfalfa hay for a single 18-d period. Digestion in the large intestine accounted for 2.1, .2, 3.6, and 6.4% of total tract digestion of organic matter, starch, ADF, and NDF, respectively; however, feed intake was not as great as in the first trial. Although conditions of these studies differed from those commonly experienced by lactating cows, the underlying principals should apply. The large intestine would be expected to make an even greater contribution to total tract digestion in lactating cows consuming proportionally more DM.

Postruminal passage of inert particles varying in specific gravity, length, and time of administration in relation to feeding, as well as interactions among these factors, were studied in four ruminally cannulated steers. Animals were allowed access to a 40% grain mix, 60% long alfalfa hay diet for 6 h daily. Eleven combinations of particle specific gravity (.9, 1.17, 1.41, or 1.77) and length (1, 5, or 10 mm) were used. Two hundred particles of each combination were placed in the abomasum at the beginning of the meal, the end of the meal, or 6 or 12 h after the end of the meal. Recovery of particles in feces within 24 or 48 h of administration and times of first appearance and maximal concentration were examined. Particle recovery 24 h after dosing as a percentage of 48-h recovery and time of maximal concentration in feces best described postruminal passage of inert particles. Passage was affected by specific gravity, but not length, of particles. Those having a specific gravity of 1.17 passed most quickly. Time at which particles were placed in the abomasum in relation to feeding affected the passage of particles varying in specific gravity. This interaction may be important in studies of ruminal passage that depend on marker appearance in feces.

Contribution of cecal and ruminal VFA to metabolizable energy was investigated in steers with cannulas in both the rumen and cecum. Animals were fed ad libitum so that data would be applicable to the lactating dairy cow. Diets assigned within a 4×4 Latin square were: 20% long alfalfa hay and 80% concentrate; 15% pelleted alfalfa, 5% hay and 80% concentrate; 80% hay and 20% concentrate; 60% pellets, 20% hay and 20% concentrate. Intake of DM was unaffected by diet. Cecal fluid pH, osmolality, and concentrations of valerate and isovalerate were unaffected by diet. Concentrations of total VFA, acetate, propionate, butyrate, and lactate in the cecum increased with proportion of grain in the diet. The high grain diets depressed cecal ammonia concentration and acetate to propionate ratio. Acetate production in the cecum was higher with the high grain diets whereas that in the rumen was lower. Production of propionate and butyrate in both the cecum and rumen was unaffected by diet. Cecal VFA provided 8.6% of metabolizable energy intake, on average. Contribution of ruminal VFA to total metabolizable energy was affected by diet, accounting for 72, 51, 74, and 52% of metabolizable energy from the 20% hay, 20% pelleted alfalfa, 80% hay, and 80% pelleted alfalfa, respectively. Cecal VFA were an important source of energy for ad libitumfed steers; this contribution would undoubtedly increase with increasing feed intake.