Biomedical subjects

L O Tedeschi

Publications and source records attributed to L O Tedeschi.

At least 19 recordsLinked to original sources

PubMed2007

Evaluation of protein fractionation systems used in formulating rations for dairy cattle.

Production efficiency decreases when diets are not properly balanced for protein. Sensitivity analyses of the protein fractionation schemes used by the National Research Council Nutrient Requirement of Dairy Cattle (NRC) and the Cornell Net Carbohydrate and Protein System (CNCPS) were conducted to assess the influence of the uncertainty in feed inputs and the assumptions underlying the CNCPS scheme on metabolizable protein and amino acid predictions. Monte Carlo techniques were used. Two lactating dairy cow diets with low and high protein content were developed for the analysis. A feed database provided by a commercial laboratory and published sources were used to obtain the distributions and correlations of the input variables. Spreadsheet versions of the models were used. Both models behaved similarly when variation in protein fractionation was taken into account. The maximal impact of variation on metabolizable protein from rumen-undegradable protein (RUP) was 2.5 (CNCPS) and 3.0 (NRC) kg/d of allowable milk for the low protein diet, and 3.5 (CNCPS) and 3.9 (NRC) kg/d of allowable milk for the high protein diet. The RUP flows were sensitive to ruminal degradation rates of the B protein fraction in NRC and of the B2 protein fraction in the CNCPS for protein supplements, energy concentrates, and forages. Absorbed Met and Lys flows were also sensitive to intestinal digestibility of RUP, and the CNCPS model was sensitive to acid detergent insoluble crude protein and its assumption of complete unavailability. Neither the intestinal digestibility of the RUP nor the protein degradation rates are routinely measured. Approaches need to be developed to account for their variability. Research is needed to provide better methods for measuring pool sizes and ruminal digestion rates for protein fractionation systems.

Amino Acids, Essential↗

PubMed2006

Energy and protein requirements for maintenance and growth of Boer crossbred kids.

Meat production by goats has become an important livestock enterprise in several parts of the world. Nonetheless, energy and protein requirements of meat goats have not been defined thoroughly. The objective of this study was to determine the energy and protein requirements for maintenance and growth of 34 (3/4) Boer x (1/4) Saanen crossbred, intact male kids (20.5 +/- 0.24 kg of initial BW). The baseline group was 7 randomly selected kids, averaging 21.2 +/- 0.36 kg of BW. An intermediate group consisted of 6 randomly selected kids, fed for ad libitum intake, that were slaughtered when they reached an average BW of 28.2 +/- 0.39 kg. The remaining kids (n = 21) were allocated randomly on d 0 to 3 levels of DMI (treatments were ad libitum or restricted to 70 or 40% of the ad libitum intake) within 7 slaughter groups. A slaughter group contained 1 kid from each treatment, and kids were slaughtered when the ad libitum treatment kid reached 35 kg of BW. Individual body components (head plus feet, hide, internal organs plus blood, and carcass) were weighed, ground, mixed, and subsampled for chemical analyses. Initial body composition was determined using equations developed from the composition of the baseline kids. The calculated daily maintenance requirement for NE was 77.3 +/- 1.05 kcal/kg(0.75) of empty BW (EBW) or 67.4 +/- 1.04 kcal/kg(0.75) of shrunk BW. The daily ME requirement for maintenance (118.1 kcal/kg(0.75) of EBW or 103.0 kcal/kg(0.75) of shrunk BW) was calculated by iteration, assuming that the heat produced was equal to the ME intake at maintenance. The partial efficiency of use of ME for NE below maintenance was 0.65. A value of 2.44 +/- 0.4 g of net protein/kg(0.75) of EBW for daily maintenance was determined. Net energy requirements for growth ranged from 2.55 to 3.0 Mcal/kg of EBW gain at 20 and 35 kg of BW, and net protein requirements for growth ranged from 178.8 to 185.2 g/kg of EBW gain. These results suggest that NE and net protein requirements for growing meat goats exceed the requirements previously published for dairy goats. Moreover, results from this study suggest that the N requirement for maintenance for growing goats is greater than the established recommendations.

Animal Feed↗

PubMed2006

Identifying differences in feed efficiency among group-fed cattle.

Identification of efficient animals in the postweaning growth phase for use in selection for improved feed efficiency is important to improve the economic and environmental sustainability of the beef cattle industry. Progeny testing using group-fed animals in commercial feedlots is the most common and practical method used to evaluate postweaning growth on large numbers of animals. We developed the Cornell Value Discovery System (CVDS) to dynamically predict growth rate, accumulated weight, days required to reach target body composition, carcass weight, and composition of individual beef cattle fed in group pens. Observed BW, ADG, BW at 28% empty body fat (EBF), breed type, environmental conditions, and dietary ME concentration are used by the CVDS to predict, for each animal in a pen, the feed DM required for maintenance (FFM), the feed DM required for gain, and the total DM required for maintenance and gain (DMR). The CVDS then computes DMR-to-ADG ratio (DMR:ADG), which is a feed conversion measure, and ADG-to-DMR ratio (ADG:DMR), which is a feed efficiency measure, for each animal. This study used the observed F:G ratio of 362 individually fed steers to evaluate CVDS-predicted indicators of feed efficiency and the Kleiber ratio. A subset of 37 data points was used to evaluate residual feed intake (RFI) as an indicator of feed efficiency. The database included 4 published studies, each with detailed individual animal description, environment, diet, and body composition information. The CVDS-predicted DMR:ADG accounted for 84% of the variation in the actual F:G ratio with a mean bias of 1.94% (P = 0.20). The predicted FFM to actual DMI ratio had a high correlation with actual ADG (R2 = 0.76), and indicated a decay-type nonlinear dilution of FFM as ADG increased. The CVDS-predicted ADG:DMR and the Kleiber ratio had a significant (R2 = 0.88) logarithmic relationship. In an analysis of a contemporary group within the database, RFI was highly correlated with the F:G ratio (r = 0.71). There was a positive relationship between RFI and EBF. The RFIM (DMI - DMR) was moderately correlated with DMI and ADG (0.37 and -0.38; respectively), suggesting that selecting for low RFI(M) would decrease DMI and increase ADG in this database. We conclude that the CVDS model can be used to identify differences in the F:G and G:F ratios by predicting DMR for individual growing cattle fed in groups.

Animal Feed↗

PubMed2006

Effects of phase feeding of protein on performance, blood urea nitrogen concentration, manure nitrogen:phosphorus ratio, and carcass characteristics of feedlot cattle.

Two experiments with a randomized complete block design were conducted to determine the effects of phase feeding of CP on performance, blood urea nitrogen (BUN), manure N:P ratio, and carcass characteristics of steers fed in a feedlot. In Exp. 1, 45 crossbred steers (initial BW = 423 +/- 3.3 kg) were individually fed a diet formulated to contain 13.0% CP (DM basis) for 62 d. On d 63, the dietary CP was maintained at 13.0% or formulated to contain 11.5 or 10.0% CP until slaughter. Actual CP values were 12.8, 11.8, and 9.9%, respectively. Reducing the CP concentration of the diet did not affect ADG of steers from d 62 to 109 (P = 0.54) or over the 109-d feeding period (1.45, 1.50, and 1.49 kg/d for 13.0, 11.5, and 10.0% CP, respectively; P = 0.85). No differences (P > 0.12) among treatments were detected for BUN concentrations on d 0, 62, or 109. Gain:feed, DMI, and carcass characteristics did not differ among treatments (P > 0.10). In Exp. 2, 2 trials were conducted using 184 (initial BW = 406 +/- 2.6 kg) and 162 (initial BW = 342 +/- 1.9 kg) crossbred steers. Data from the 2 trials were pooled for statistical analysis, and trial effect was added to the statistical model. Steers were fed a diet formulated to contain 13.0% CP until reaching approximately 477 kg. When the average BW of the pen was 477 kg, diets were maintained at 13.0% CP or reduced to contain 11.5 or 10.0% CP. Actual CP values were 12.4, 11.5, and 9.3% CP for treatments 13.0, 11.5, and 10.0% CP, respectively. Reducing the CP content of the diet did not affect ADG after the diet changed (P = 0.16) or throughout the finishing period (P = 0.14). Immediately before slaughter, steers fed the 13.0% CP diet had greater (P < 0.001) BUN concentrations than steers fed the 11.5 and 10.0% CP diets. Carcasses from cattle fed the 11.5% CP diet had greater (P = 0.02) fat thickness than the 13.0 and 10.0% CP treatments, whereas carcasses from cattle fed 13.0% CP had greater (P = 0.004) marbling scores than steers fed the 11.5 or 10.0% CP diets. Other carcass characteristics, DMI, and G:F did not differ (P > 0.10) among treatments. The N:P ratio was increased with the 10.0% CP diet (P = 0.02) compared with the 11.5 or 13.5% CP treatments; however, manure composition did not differ (P > 0.10) among treatments. These results indicate that reduced CP concentration during the finishing period does not affect feedlot performance but can improve the N and P relationship in the manure.

Animal Feed↗

PubMed2006

Using ultrasound measurements to predict body composition of yearling bulls.

Carcass traits have been successfully used to determine body composition of steers. Body composition, in turn, has been used to predict energy content of ADG to compute feed requirements of individual animals fed in groups. This information is used in the Cornell value discovery system (CVDS) to predict DM required (DMR) for the observed animal performance. In this experiment, the prediction of individual DMR for the observed performance of group-fed yearling bulls was evaluated using energy content of gain, which was based on ultrasound measurements to estimate carcass traits and energy content of ADG. One hundred eighteen spring-born purebred and crossbred bulls (BW = 288 +/- 4.3 kg) were sorted visually into 3 marketing groups based on estimated days to reach USDA low Choice quality grade. The bulls were fed a common high-concentrate diet in 12 slatted-floor pens (9 to 10 head/pen). Ultrasound measurements including back-fat (uBF), rump fat, LM area (uLMA), and intramuscular fat were taken at approximately 1 yr of age. Carcass measurements including HCW, backfat over the 12th to 13th rib (BF), marbling score (MRB), and LM area (LMA) were collected for comparison with ultrasound data for predicting carcass composition. The 9th to 11th-rib section was removed and dissected into soft tissue and bone for determination of chemical composition, which was used to predict carcass fat and empty body fat (EBF). The predicted EBF averaged 23.7 +/- 4.0%. Multiple regression analysis indicated that carcass traits explained 72% of the variation in predicted EBF (EBF = 16.0583 + 5.6352 x BF + 0.01781 x HCW + 1.0486 x MRB - 0.1239 x LMA). Because carcass traits are not available on bulls intended for use as herd sires, another equation using predicted HCW (pHCW) and ultrasound measurements was developed (EBF = 39.9535 x uBF - 0.1384 x uLMA + 0.0867 x pHCW - 0.0897 x uBF x pHCW - 1.3690). This equation accounted for 62% of the variation in EBF. The use of an equation to predict EBF developed with steer composition data overpredicted the EBF predicted in these experiments (28.7 vs. 23.7%, respectively). In a validation study with 37 individually fed bulls, the use of the ultrasound-based equation in the CVDS to predict energy content of gain accounted for 60% of the variation in the observed efficiency of gain, with 1.5% bias, and identified 3 of the 4 most efficient bulls.

Adipose Tissue↗

PubMed2006

Evaluation of the passage rate equations in the 2001 Dairy NRC model.

Dairy ration formulation to meet protein and amino acid requirements with the National Research Council Nutrient Requirements of Dairy Cattle (NRC, 2001) model depends on accuracy of predicting feed passage rates out of the rumen. The NRC (2001) passage rate (Kp) equations were evaluated for validity and sensitivity to input variables in predicting supplies of rumen degraded protein, rumen undegraded protein, and metabolizable protein. The database used in the development of the 3 Kp equations (for dry forage, wet forage, and concentrate) was used to independently derive the 3 equations using a meta-analysis technique. To extract quantitative relationships between statistically significant input variables and rate of passage, a random coefficients model that used each study effect as a random variable was used. The database was comprised of studies that only used rare earth markers. Outliers were identified by acceptance criteria defined a priori or the difference in fit statistic (DFFITS) value; 319, 63, and 139 treatment means were used to develop the Kp equations for dry forage, wet forage, and concentrate, respectively. We found that the sign of the regression coefficient for concentrate content in diet dry matter in the equation for Kp dry forage was inverted; it should be positive. A sensitivity analysis was conducted with a spreadsheet version of the NRC (2001) model developed for this study, using the Monte Carlo technique. The sensitivity analysis indicated that all Kp predictions were the most sensitive to variation in DM intake, and thus accurate measurement of DM intake is the most important factor in predicting Kp. Predictions for protein supply (rumen degraded protein, rumen undegraded protein, and metabolizable protein) were sensitive to variability in amount of feed crude protein (CP, %DM), digestion rate (Kd) of the B fraction of feed CP (%/h), and the Kp for concentrate (%/h), due to the high proportion of dietary CP in lactating dairy rations coming from concentrates. The sensitivity analysis indicated that accurate determinations of DMI, the Kd of the B fraction of feed CP, and feed CP are the most important variables needed to predict MP supply in lactating dairy cows with the NRC (2001) model. We conclude that the empirical Kp equations in the model are suitable for predicting passage rate in lactating dairy cows. More accurate predictions of Kp will require the development of a more mechanistic model that accounts for more of the biologically important variables (e.g., physical property of particles, liquid flow, and timely variation of intake) affecting passage rate.

Algorithms↗

PubMed2006

Accounting for energy and protein reserve changes in predicting diet-allowable milk production in cattle.

Current ration formulation systems used to formulate diets on farms and to evaluate experimental data estimate metabolizable energy (ME)-allowable and metabolizable protein (MP)-allowable milk production from the intake above animal requirements for maintenance, pregnancy, and growth. The changes in body reserves, measured via the body condition score (BCS), are not accounted for in predicting ME and MP balances. This paper presents 2 empirical models developed to adjust predicted diet-allowable milk production based on changes in BCS. Empirical reserves model 1 was based on the reserves model described by the 2001 National Research Council (NRC) Nutrient Requirements of Dairy Cattle, whereas empirical reserves model 2 was developed based on published data of body weight and composition changes in lactating dairy cows. A database containing 134 individually fed lactating dairy cows from 3 trials was used to evaluate these adjustments in milk prediction based on predicted first-limiting ME or MP by the 2001 Dairy NRC and Cornell Net Carbohydrate and Protein System models. The analysis of first-limiting ME or MP milk production without adjustments for BCS changes indicated that the predictions of both models were consistent (r(2) of the regression between observed and model-predicted values of 0.90 and 0.85), had mean biases different from zero (12.3 and 5.34%), and had moderate but different roots of mean square errors of prediction (5.42 and 4.77 kg/d) for the 2001 NRC model and the Cornell Net Carbohydrate and Protein System model, respectively. The adjustment of first-limiting ME- or MP-allowable milk to BCS changes improved the precision and accuracy of both models. We further investigated 2 methods of adjustment; the first method used only the first and last BCS values, whereas the second method used the mean of weekly BCS values to adjust ME- and MP-allowable milk production. The adjustment to BCS changes based on first and last BCS values was more accurate than the adjustment to BCS based on the mean of all BCS values, suggesting that adjusting milk production for mean weekly variations in BCS added more variability to model-predicted milk production. We concluded that both models adequately predicted the first-limiting ME- or MP-allowable milk after adjusting for changes in BCS.

Adipose Tissue↗

PubMed2005

The effect of milk intake on forage intake and growth of nursing calves.

Thirty-nine Holstein steer calves were assigned to one of five treatments at birth and individually fed for 200 d with milk replacer reconstituted to equal the fat and protein concentration of beef cow milk. Treatment levels were the quantities of reconstituted milk fed per day based on lactation curves, which were based on peak milk levels (PML) of 2.72, 5.44, 8.16, 10.88, and 13.6 kg/d, respectively. In addition to reconstituted milk, chopped alfalfa hay was offered ad libitum to allow for maximal voluntary forage consumption. All calves were fed a high-energy diet postweaning until they reached a similar degree of fatness in the 12th rib (4 to 5% chemical fat) as determined by ultrasound. There were differences (P < 0.05) among groups in weaning weight, preweaning ADG, age, and weight at slaughter. During the preweaning phase, there was a linear relationship (P < 0.01) for daily milk and forage DE intake; however, DE intake per unit of BW did not differ across treatments (P = 0.06). Increasing PML resulted in a linear (P < 0.01) decrease in alfalfa hay intake in the preweaning phase, and G:F increased quadratically (P < 0.01). During the postweaning phase, preweaning milk intake had no meaningful effect on postweaning ADG, but overall ADG had a linear relationship (P < 0.01) with preweaning milk level. There was no effect of PML on the 12th-rib lipid percent, marbling score, or quality grade, but protein and fat concentration in the carcass and empty BW increased linearly (P < 0.01) with PML. The group fed at 2.72 kg/d PML was 58 kg lighter (P = 0.03) and required 34 d more (P < 0.01) to reach the predetermined degree of fatness at slaughter than the group fed at 13.6 kg/d PML, suggesting that increased milk production by the dam can decrease the number of days to the slaughter weight at which a similar rib lipid concentration is reached.

Adipose Tissue↗

PubMed2004

A mechanistic model for predicting the nutrient requirements and feed biological values for sheep.

The Cornell Net Carbohydrate and Protein System (CNCPS), a mechanistic model that predicts nutrient requirements and biological values of feeds for cattle, was modified for use with sheep. Published equations were added for predicting the energy and protein requirements of sheep, with a special emphasis on dairy sheep, whose specific needs are not considered by most sheep-feeding systems. The CNCPS for cattle equations that are used to predict the supply of nutrients from each feed were modified to include new solid and liquid ruminal passage rates for sheep, and revised equations were inserted to predict metabolic fecal N. Equations were added to predict fluxes in body energy and protein reserves from BW and condition score. When evaluated with data from seven published studies (19 treatments), for which the CNCPS for sheep predicted positive ruminal N balance, the CNCPS for sheep predicted OM digestibility, which is used to predict feed ME values, with no mean bias (1.1 g/100 g of OM; P > 0.10) and a low root mean squared prediction error (RMSPE; 3.6 g/100 g of OM). Crude protein digestibility, which is used to predict N excretion, was evaluated with eight published studies (23 treatments). The model predicted CP digestibility with no mean bias (-1.9 g/100 g of CP; P > 0.10) but with a large RMSPE (7.2 g/100 g of CP). Evaluation with a data set of published studies in which the CNCPS for sheep predicted negative ruminal N balance indicated that the model tended to underpredict OM digestibility (mean bias of -3.3 g/100 g of OM, P > 0.10; RMSPE = 6.5 g/100 g of OM; n = 12) and to overpredict CP digestibility (mean bias of 2.7 g/100 g of CP, P > 0.10; RMSPE = 12.8 g/100 g of CP; n = 7). The ability of the CNCPS for sheep to predict gains and losses in shrunk BW was evaluated using data from six studies with adult sheep (13 treatments with lactating ewes and 16 with dry ewes). It accurately predicted variations in shrunk BW when diets had positive N balance (mean bias of 5.8 g/d; P > 0.10; RMSPE of 30.0 g/d; n = 15), whereas it markedly overpredicted the variations in shrunk BW when ruminal balance was negative (mean bias of 53.4 g/d, P < 0.05; RMSPE = 84.1 g/d; n = 14). These evaluations indicated that the Cornell Net Carbohydrate and Protein System for Sheep can be used to predict energy and protein requirements, feed biological values, and BW gains and losses in adult sheep.

Animal Feed↗

PubMed2003

Production and economic potentials of cattle in pasture-based systems of the western Amazon region of Brazil.

Our objectives were to evaluate strategies to improve productivity and economic returns from beef and dual-purpose cattle systems based on data collected on one dual-purpose (Bos taurus x Bos indicus) and two beef (Nellore) cattle farms in the western Amazon region of Brazil. Forage chemical composition and digestion rates of carbohydrate fractions of grazed Brachiaria decumbens and Brachiaria brizantha cv. Marandu grasses and Pueraria phaseoloides (tropical kudzu) legume were measured monthly during a 9-mo period from the end of one dry season to the end of the subsequent rainy season. Measurements of milk and growth responses to grazing these forages were used to predict animal productivity responses to dietary nutrient availability throughout an annual cycle. The ME available for gain in our simulations was always more limiting than metabolizable protein. The predicted ME available for gain was 0.50 kg/d for steers grazing B. brizantha and 0.40 kg/d for finishing steers grazing B. decumbens. Grasses contained more NDF and neutral detergent insoluble protein and less ME (P < 0.05) in the rainiest months than in the less rainy season, which resulted in 20% less predicted weight gain by growing steers (P < 0.05). Supplementation with sorghum grain was required to increase milk production and growth by 25 or 50% per animal, respectively, but this strategy was less profitable than current forage-only diets. Greater productivity of land and labor from higher stocking indicated greater net margins for beef production, but not for milk. This study suggested that more intensive beef production by judicious fertilization of grass-legume pastures and greater stocking density is the preferable strategy for owners of these cattle systems to improve economic returns under current conditions. It also might help decrease the motivation for additional forest clearing.

Animal Feed↗

PubMed2002

Energy requirement for maintenance and growth of Nellore bulls and steers fed high-forage diets.

Data from three comparative slaughter experiments with individually fed Nellore bulls (n = 31) and steers (n = 66) were utilized to determine their NEm and NEg requirements when fed high-forage diets. The experimental design provided ranges in ME intake, BW, and ADG for the development of regression equations to predict NEm and NEg requirements. The Nellore bulls (Trial 1) were divided into two intake levels (ad libitum and 65% of the ad libitum). The steers (Trials 2 and 3) were allocated to three intake levels (ad libitum and 55 and 70% of the ad libitum). In both trials, there were three slaughter groups within each intake level. The three end points for the bulls were different days on treatment (100, 150, and 190 d and 130, 180, and 200 d, respectively, for older and younger animal subgroups). The steers were slaughtered when animals of the ad libitum treatment reached 400, 440, and 480 kg shrunk BW (SBW) on average for the first, second, and third group, respectively. For all body composition determinations, whole empty body components were weighed, ground, and subsampled for chemical analysis. In each of the trials, initial body composition was determined with equations developed from a baseline slaughter group, using SBW and empty BW (EBW), fat (EBF), and protein (EBP) as variables. The NEm was similar for bulls and steers; NEm averaged 77.2 kcal/ kg0.75 EBW. However, the efficiency of conversion of ME to net energy for maintenance was greater for steers than for bulls (68.8 and 65.6%, respectively), indicating that bulls had a greater ME requirement for maintenance than steers (5.4%; P < 0.05). Our analyses do not support the NRC (2000) conclusion that Nellore, a Bos indicus breed, has a lower net energy requirement for maintenance than Bos taurus breeds. An equation developed with the pooled data to predict retained energy (RE) was similar to the NRC (2000) equation. A second equation was developed to predict RE adjusted for degree of maturity (u): RE = (6.45 - 2.58/u) x EWG x e(0.469) x u), where u = current EBW/final EBW in which final EBW was 365 kg for steers and younger bulls and 456 kg for older bulls at 22% EBF, respectively.

Animals↗

PubMed2002

The effects of implant strategy on finished body weight of beef cattle.

We summarized experimental data to quantify the change in final BW due to a particular implant strategy when cattle are adjusted to the same final body composition. The database developed for this study included 13 implant trials involving a total of 13,640 animals (9,052 steers and 4,588 heifers). Fifteen different implant strategies were used among these trials, including no implant (control), single implants, and combinations of implants. Individual carcass data collected at slaughter were used to calculate the adjusted final shrunk BW at 28% empty body fat (AFBW) for each treatment group within a trial, then the implant treatments were grouped into categories according to their effect on weight at 28% empty body fat (four groups for steers and two groups for heifers). All differences in AFBW between categories were significant (P < 0.01), indicating an incremental anabolic implant dose response in AFBW over unimplanted animals. Values for AFBW ranged from 520 kg in unimplanted steers to 564 kg in steers implanted and reimplanted with Revalor-S. For heifers, AFBW ranged from 493 kg in unimplanted heifers to 535 kg in heifers implanted and reimplanted with Revalor-H. After accounting for differences in mean BW and composition of gain, implanted steers and heifers had 4.2 and 3.1% higher apparent diet ME values, respectively. Increasing the anabolic implant dose increases the weight at which animals reach a common body composition. This study indicates that anabolic implant response is due to a combination of a reduced proportion of the DMI required for maintenance, reduced energy content of gain, and efficiency of use of absorbed energy.

Adipose Tissue↗

PubMed2002

The effect of ruminal fluid preparations on the growth and health of newborn, milk-fed dairy calves.

The objective of this study was to determine the effect of oral doses of ruminal fluid (RF) on the growth and health of newborn, milk-fed heifer dairy calves (0 to 6 wk of age). Calves given 8 ml of RF each day until weaning gained more weight and had fewer scours than controls that did not receive RF. Because RF that was exposed to oxygen or was autoclaved also gave a response, it is unlikely that the preparations were acting as a probiotic. When the RF was centrifuged to separate the cells (RFC) from the fluid (RFS), both fractions had similar activity, and this result indicated that the response was not nutritional; that is, 1) RFC supplied a small amount of protein (approximately 8 mg/d), but RFS had much less protein, and 2) RFS had volatile fatty acid, but RFC had little if any volatile fatty acid. However, both RFS and RFC had bacterial polysaccharide, and bacterial polysaccharide has strong antigenic properties. In the first three studies, treated calves were given RF preparations each day until weaning (6 wk), but a subsequent experiment indicated that calves given autoclaved RF for only 5 d (d 1 to 5) also had greater body weight gains during the first 2 wk of life and fewer scours than untreated controls. Given that the dosage of RF was small and the material could be autoclaved to prevent disease transmission, RF supplementation could be a practical tool for improving calf health.

Animal Feed↗

PubMed2001

The amino acid profiles of the whole plant and of four plant residues from temperate and tropical forages.

This study compared the amino acid (AA) profile of five residues (original forage, borate-phosphate buffer residue (BPR), neutral detergent fiber residue with (NDF+) and without (NDF-) sodium sulfite, and acid detergent fiber residue (ADF). Fourteen grasses and legumes from tropical and temperate regions were used in this study. The use of sodium sulfite did not affect the NDF concentration, but the NDF insoluble protein was lower (P < 0.05) in the NDF+ than in the NDF- (3.9 vs 4.5% DM, respectively). For all of the amino acids tested, the amino acid content, expressed as a percentage of CP, was lower in the ADF residue than in the original forage. There were no differences in the amino acid concentrations of the NDF- and NDF+ extracts (P > 0.05). Only in the case of methionine was there a difference in the amount of amino acid when the original forage was compared with the BPR (1.84 vs 1.45 % CP). When the AA profile of each residue was corrected for the AA content of the ADF, no difference was observed between the AA profile of the original forage and of the BPR (P > 0.05). Similar to the result without correction for the amino acids in ADF, the AA profiles of the NDF+ and NDF- fractions were similar (P > 0.05). From this result, we infer that the sodium sulfite had similar effects on all AA in the NDF residue that we tested. There were differences in amino acid concentrations in the original forage and the NDF residues for several amino acids (Met, Cys, Lys, Thr, Arg, Ile, Leu, and Phe) (P < 0.05). When the amino acid values of the original forage and the BPR were used with animal data in the Cornell Net Carbohydrate and Protein System model, few differences in animal predicted performance were evident. These findings suggest that the AA profile of the original forage can be used to predict the AA profile of the undegraded intake protein instead of using the borate-phosphate buffer residue for amino acid analyses. This would simplify obtaining feed amino acid values for use in the Cornell Net Carbohydrate and Protein System.

Amino Acids↗

PubMed2001

Predicting individual feed requirements of cattle fed in groups.

A published model designed to predict individual feed required for the observed shrunk BW and ADG of growing cattle when fed in groups was modified and evaluated to improve its accuracy. This model is needed to accurately bill feed and compute cost of gain in marketing programs based on individual animal management. Because of its importance in predicting energy required for growth, a database of 401 steers was used to develop an equation to predict percentage of empty-body fat (EBF) from carcass measurements (12th rib fat thickness, hot carcass weight, USDA quality grade, and longissimus muscle area), which accounted for 61% of the variation in EBF with no bias (P > 0.1). When tested with an independent data set of 951 steers, the equation accounted for 51% of the variation with 1% proportional bias. The large variation in the carcass measurements at a particular EBF observed in this study indicates further improvement is limited by the inability of carcass measurements to account for variation in fat distribution in the various carcass components. Because of its importance in setting the target end point, a database of 1,355 steers and heifers was used to determine the relationship between EBF and USDA quality grade. These data indicate growing and finishing cattle reach Select and low-Choice quality grades at an EBF of 26.15 +/- 0.19 and 28.61 +/- 0.20%, respectively (P < 0.05). A data set of 228 steers from different breeds from two serial slaughter studies indicated 14.26 +/- 1.52 kg of empty BW change are required to increase EBF one percentage unit for cattle fed high-energy diets; this adjustment is needed to adjust final shrunk BW to the target EBF end point. The model to predict DM required with modifications developed in this study was evaluated with data from 365 individually fed cattle and it accounted for 74% of the variation in observed DM consumed with no bias (P > 0.1). When the revised model was applied to a commercial feedlot data set containing 12,105 steers and heifers, the total observed DM consumed was predicted with a bias of less than 1%. The model presented in this study accounts for differences known to affect animal requirements (breed type, BW and ADG, and weight at the target EBF end point) and can be used to fairly allocate feed to individuals fed in a group under commercial feedlot conditions.

Animal Feed↗

PubMed2001

Effect of monensin on the performance and nitrogen utilization of lactating dairy cows consuming fresh forage.

We conducted a lactation trial with a fresh forage diet in order to evaluate 1) the effects of monensin on nitrogen metabolism, and 2) the Cornell Net Carbohydrate and Protein System (CNCPS). Thirty Holstein cows in midlactation (eight fitted with ruminal fistulas) were gradually introduced to a fresh forage diet. A concentrate mix based on corn meal was fed before the a.m. and p.m. milking times 0730 and 1730 h, then the fresh forage was fed at 0830 and 1830 h. Fifteen cows each were allocated to a control (no monensin) and a treatment group receiving 350 mg/cow per day of monensin in the p.m. concentrate feeding. A 7-d fecal and urine collection period and a 3-d rumen sampling period were conducted with the fistulated cows. After the lactation study was concluded, the fistulated cows were fed forage regrowth and a 3-d rumen sampling period was repeated. Monensin increased milk production by 1.85 kg. Milk fat and protein concentrations decreased and milk fat and protein yields increased, but the effects were nonsignificant. Monensin did not significantly affect DMI. Ruminal ammonia and the acetate-to-propionate ratio decreased with the addition of monensin in both fed forages. Monensin decreased fecal N output, and increased apparent N digestibility by 5.4%. Because of the decrease in ruminal ammonia and increase in apparent N digestibility, we concluded monensin was sparing amino acids from wasteful rumen degradation with a fresh forage diet. The precision of the CNCPS in predicting performance was high (r2 = 0.76), and the bias was low (overprediction of 3.6%). These results indicate that the CNCPS can be used for dairy cows consuming fresh forage and gives realistic predictions of performance.

Acetates↗

PubMed2000

Accounting for the effects of a ruminal nitrogen deficiency within the structure of the Cornell Net Carbohydrate and Protein System.

The Cornell Net Carbohydrate and Protein System (CNCPS) prediction of fiber digestion and microbial mass production from ruminally degraded carbohydrate has been adjusted to accommodate a ruminal N deficiency. The steps for the adjustment are as follows: 1) the ruminal available peptide and ammonia pools are used to determine the N allowable microbial growth; 2) this value is subtracted from the energy allowable microbial growth to obtain the reduction in microbial mass; 3) this mass reduction is allocated between pools of bacteria digesting fiber (FC) and nonfiber (NFC) carbohydrate according to their original proportions in the energy allowable microbial growth; 4) the reduction in fermented FC is computed as the FC bacterial mass reduction divided by its yield (g bacteria/g FC digested); and 5) this reduction is added to the FC fraction escaping the rumen. Five published studies included information that allowed us to evaluate the response of animals to added dietary N. These evaluations compared observed and CNCPS-predicted ADG with and without this adjustment. The adjustment decreased the CNCPS overprediction of ADG from 19.2 to 4.7%, mean bias declined from .16 to .04 kg/d, and the r2 of the regression between observed and metabolizable energy (ME) or metabolizable protein allowable ADG was increased from .83 to .88 with the adjustment. When the observed dry matter intake was regressed against CNCPS-predicted DMI with an adjustment for reduction in cell wall digestibility, the r2 was increased from .77 to .88. These results indicated the adjustment for ruminal nitrogen deficiency increased the accuracy of the CNCPS model in evaluating diets of growing animals when ruminally degraded N is deficient.

Animals↗

PubMed2000

Whole-herd optimization with the Cornell Net Carbohydrate and Protein System. I. Predicting feed biological values for diet optimization with linear programming.

We developed a diet optimizer for least-cost diet formulation with the Cornell Net Carbohydrate and Protein System (CNCPS) using linear programming. The CNCPS model is intrinsically nonlinear, and feed biological values vary with animal and feed characteristics. To allow linear diet optimization, we first used the CNCPS model to generate biological values to characterize the energy and protein content of each feed for the specific group for which the diet was being formulated. The biological values used were metabolizable energy (Mcal/kg), metabolizable protein [(% dry matter (DM)], passage rate (%/h), bacteria yield efficiencies (g/g), and degradation rate of the carbohydrate B2 fraction (%/h). In addition, the ruminal balances for nitrogen and peptides were included in the optimizer to optimize ruminal degradation of fiber. The objective function was to minimize diet cost subject to animal requirement and feed availability constraints. The animal constraints were set by requirements for DM intake (kg/d), metabolizable energy (Mcal/kg), metabolizable protein (%DM), and effective neutral detergent fiber (%DM) for a given level of production. Data from a dairy farm were used to evaluate this linear diet optimizer. Across all classes of dairy cattle, the CNCPS 4.0 model typically obtained a solution in less than six iterations that met the requirements with nearly 100% accuracy. We conclude this linear optimizer can be used to accurately formulate least-cost diets with the CNCPS model.

Animals↗