Control 1.61 Mcal of net energy for lactation (NEL)/kg of dry matter (DM), high grain (1.70 Mcal of NEL/kg of DM), or high fat 1.70 Mcal of NEL/ kg of DM with 2.3% tallow (DM basis) diets were fed to ...43 cows (150±3.1 d in milk) during mid to late lactation to determine effects on performance characteristics, metabolic parameters, or both during mid to late lactation, the dry period, and the first 100 d of the next lactation. All cows received identical diets during the dry period and during early lactation. Increasing the energy density of the diets during mid to late lactation increased DM intake (DMI), plasma nonesterified fatty acid concentration, milk production, and milk protein yield. Compared with the high grain diets, fat supplementation decreased DMI and the percentage of milk protein but increased plasma nonesterified fatty acid concentration without causing elevation of liver triglyceride at the end of mid to late lactation. Increased energy density of the diets did not affect body condition score during mid to late lactation. There were no residual effects for any of the treatments on DMI, lactation performance, or body weight in the subsequent lactation. However, energy supplementation during mid to late lactation increased liver triglyceride content after calving. Compared with high fat diets, high grain diets fed during mid to late lactation increased plasma β-hydroxybutyrate concentration in the subsequent lactation. High energy diets fed during mid to late lactation may influence lipid metabolism during the following lactation.
The present study examined the effects of diet on the concentration and excretion of allantoin in milk and the relationship between allantoin in milk and urine of dairy cows. Results are reported ...from three experiments. In Experiment 1, four diets with two different protein percentages and two different rumen degradabilities were fed to 12 cows in a continuous trial. In Experiment 2, four diets with different protein balance values in the rumen were fed to four cows in a 4 × 4 Latin square design. In Experiment 3, four diets with different contents of concentrate and fat were fed to four cows in two incomplete 2 × 2 Latin squares. The excretion of allantoin N in milk increased as dry matter intake increased (Experiment 1) and as the concentrate in the diet increased (Experiment 3). In Experiments 1 and 3, the excretion of allantoin in milk was correlated with its concentration in milk and with its excretion in urine. In the three experiments, allantoin excretion in milk was closely correlated with milk yield. The amount of allantoin secreted in milk represented a small proportion (0.63 to 1.34%) of the total excretion in urine and milk. The proportion of allantoin secreted in milk was negatively correlated with the urinary excretion of allantoin in Experiments 2 and 3 and positively correlated with the excretion of allantoin in milk in Experiment 1. In Experiments 1 and 2, the proportion of allantoin excreted in milk was not constant but increased as milk yield increased.
A review and comparison of feedstuff amino acid digestibility values for poultry and swine is presented and the use of amino acid digestibility and availability is discussed. The effect of ...overprocessing on amino acid digestibility of oilseed meals is also reviewed. In general, true digestible amino acid values determined in cecectomized roosters are 5–10% higher than apparent digestibility values determined in ileal-cannulated pigs. Several studies have shown beneficial responses to formulating diets based digestible amino acid values vs. total amino acid values. However, feedstuff amino acid digestibility values determined via balance assays are often higher than amino acid availability values determined by slope-ratio growth assays. In addition, recent work with pigs suggests that the ileal digestibility assay overestimates the amount of amino acids available or utilizable for protein synthesis. Finally, overprocessing of oilseed meals greatly reduces the amount of digestible or available lysine, whereas other amino acids are usually much less affected. Protein solubility in KOH is a good in vitro assay for detecting decreased protein quality due to overprocessing and the use of Coomassie Blue dye simplifies and reduces the time required to conduct the assay.
An in vitro procedure was developed to estimate rate and extent of ruminal protein degradation using 15NH3 to quantify uptake of protein degradation products for microbial protein synthesis. ...Incubations were conducted for 6 h in stirrer flasks with ruminal inoculum plus buffer, reducing solution, pectin, soluble carbohydrates, and added (15NH4)2SO4. Seven protein concentrates were tested in the system. Samples of media were analyzed for 15N enrichment of NH3, microbial N, and total solids N. Degradation rate was computed from net (i.e., protein-added minus blank) release of NH3 N plus net synthesis of microbial protein N; escape was estimated assuming ruminal passage rate 0.06/h. Over the course of the incubations, pH was stable at 6.6, protozoal numbers increased slightly, and microbial protein content increased by more than 200%. Free AA had not accumulated at the end of the incubations. Microbial protein synthesis was a linear function (P 0.001; r2 0.780) of extent of degradation. Mean degradation rates and ruminal escapes determined were, respectively, 0.569/h and 10% (casein), 0.148/h and 29% (solvent soybean meal), 0.036/h and 63% (expeller soybean meal), 0.026/h and 70% (low solubles fish meal), 0.063/h and 49% (high solubles fish meal), 0.034/h and 64% (corn gluten meal), and 0.050/h and 55% (roasted soybeans). Overall, degradation rates averaged 28% greater than those previously estimated using an inhibitor in vitro system; however, rates obtained for the fish meals using the 15N method were slower
Twelve crossbred barrows (initial BW of 59.7 kg) were used in nutrient balance trials to investigate the influence of adding two Bacillus products (Biomate 2B and Pelletmate Livestock, Chr. Hansen's ...Biosytems) to a 14% CP corn-soybean meal diet (.64% lysine, 0.6% Ca and 0.5% P). A 3 X 3 Latin-square design with an extra period was used. Treatments were as follows: 1) basal diet; 2) basal + Biomate 2B (BAC 1); and 3) basal + Pelletmate Livestock (BAC2). After a 7-d adaptation to metabolism crates, each 10-d period consisted of 5 d of diet adjustment followed by 4 d of total collection and 1 d for change-over. Both BAC1 and BAC2 were added at a level of 0.05% to supply approximately 3 million colony forming units per gram of diet. Pigs were fed twice daily at a daily rate of 3.2 to 3.5% of BW. Feeding BAC1 or BAC2 elevated (P 0.001) fecal Bacillus spore counts at the end of each collection period, but the effect on number of coliforms and lactic acid bacteria was not as consistent; coliform counts tended to be decreased (P 0.10) when BAC2 was fed, but not (P 0.10) when BAC1 was fed. The number of lactic acid bacteria was increased (P 0.05) when BAC1 was fed, but not (P 0.10) when BAC2 was fed. Body weights were similar among all treatments for all periods. There was no carry-over or pretreatment effect (P
The first edition of the Nutrient Requirements of Dairy Cattle was published by the National Research Council (NRC) in 1945. The current document is the sixth revised edition, published in 1989, and ...it appears that we are a few years from another edition being in print. Software designed to evaluate and formulate rations for dairy cattle commonly determine nutrient requirements using the NRC as a standard. However, the generation of new knowledge in dairy nutrition occurs more rapidly than the release of the NRC publication, and the developers of the software often modify the requirements based on more recently published research, geographical peculiarities, or factors not explicitly considered by NRC. The first step in evaluating or formulating rations is the prediction of dry matter intake (DMI). The primary variables used by NRC to predict DMI are body weight (BW) and fat-corrected milk (FCM) yield; however, developers of software programs often use different equations based on personal preference, availability of research data with given equations, and incorporation of other factors in addition to BW and FCM yield. The additional factors are included to provide a more dynamic estimation of DMI and, therefore, reduce the difference between predicted and actual DMI. Nutrients required for maintenance, lactation, and growth must be consumed in adequate quantities (e.g., kilograms or calories), but the dietary concentration of nutrients for a given animal group may differ because of DMI. Even when nutrients are fed above the requirements, dietary concentrations of nutrients may be important in some situations to minimize the risk of underfeeding caused by variability in the nutrient composition of feedstuffs and to account for interactions of certain nutrients (e.g., minerals). New research discoveries need to be incorporated into ration formulation strategies promptly, and the strategies used for ration formulation need to be dynamic.
Two experiments were designed to evaluate dietary N source and concentration on finishing steer performance and nutrient digestion. In Exp. 1, 100 steers were used in a randomized complete block ...design experiment with 2 x 2 + 1 factorially arranged treatments. Diets contained 1.93 or 2.24% N supplemented by urea or soybean meal (SBM), or 2.24% N supplemented by cottonseed meal (CSM). Steers fed SBM-supplemented diets gained 13% faster (P .01) and were 9% (P .01) more efficient converting feed to gain than steers receiving urea. Steers fed diets containing 2.24% N were 4% (P .05) more efficient than those fed diets containing 1.93% N. Steers fed CSM-supplemented diets gained 6% (P .10) less efficiently than steers receiving SBM. Increasing dietary N with urea from 1.93 to 2.24% decreased carcass weights 3%, whereas increasing dietary N with SBM increased carcass weights 3%. Carcass-adjusted gains were reduced 8% by increasing urea from .9 to 1.5% but increased 7% by increasing SBM from 6.1 to 10.5% of DM. In Exp. 2, four ruminally and duodenally cannulated steers (390 kg) were used in a 4 x 4 Latin square design experiment to evaluate urea and SBM supplementation on digestion. Diets contained no supplemental N, 1.84% N with urea or SBM as the supplement, or 2.16% N with SBM as the supplement. Total tract starch digestion, duodenal microbial N flow, and efficiency of microbial protein synthesis in the rumen were higher (P .10) in steers fed SBM- than in those fed urea-supplemented diets. Supplementation with SBM increased metabolizable protein supply and dietary energy utilization
One hundred primiparous sows were used to determine the effects of particle size of corn in lactation diets on sow and litter performance. The sows were fed a corn-soybean meal-based diet with the ...corn ground to 1,200, 900, 600, or 400 micrometer. Particle size of corn had no influence on sow BW or backfat loss (P > 0.30), subsequent weaning-to-estrus interval (P > 0.40), or percentage of sows returning to estrus (P > 0.09). However, ADFI was increased (linear effect, P < 0.04) as particle size was reduced from 1,200 to 400 microgram. Pig survivability was not affected (P > 0.30) but litter BW gain was increased by 11% when sows were fed diets with 400 vs 1,200 micrometer corn (linear effect, P < 0.05). Apparent digestibilities of DM, N, and GE were increased by 5, 7, and 7%, respectively, as particle size was reduced from 1,200 to 400 micrometer (linear effects, P < 0.001). Intake of DE was increased 14% (13.7 to 15.6 Mcal/d) as corn particle size was reduced from 1,200 to 400 micrometer. Intakes of digestible DM and N also were increased (11 and 14%, respectively), whereas fecal excretions of DM and N were decreased by 21 and 31%, respectively (linear effects, P < 0.001). Reducing particle size increased severity of ulceration and keratinization (nonzero correlations of P < 0.04 and P < 0.004, respectively) in the esophageal region of the stomach, although the changes were not associated with reduced sow performance. In conclusion, our data indicate that the optimum particle size of corn in lactation diets to maximize nutrient intake and litter weight gain in primiparous sows is near 400 micrometer.
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