Development of a novel system to estimate protein degradability in legume and grass silages

Five trials were conducted to develop a system to estimate rumen-undegradable protein (RUP) of legume and grass silages using near infrared reflectance spectroscopy. In situ procedures were the reference method used to determine silage RUP content. Trials 1, 2, and 3 were devoted to improving in situ procedures. In trial 1, alfalfa silage with and without heat treatment was incubated ruminally in 30 cows. The standard deviation of in situ RUP attributable to cow and diet was 0.82 and 3.80 g/10(-1) kg of crude protein (CP) for the unheated and heated alfalfa, respectively. Based on trial 1, it was determined that 8 cows would be required to establish RUP standards. In trial 2, low (13.3 g/10(-1) kg of CP) and high (44.5 g/10(-1) kg of CP) RUP standards were developed using eight ruminally cannulated cows. In trial 3, 11 new RUP standards were developed by mixing trial 2 RUP standards together. The RUP standards were used to employ a calibration curve technique in ruminally cannulated cows. The technique was employed in four ruminally cannulated cows to estimate RUP contents of 121 silages, and RUP values were used for near-infrared reflectance spectroscopic analysis in trial 4. Trial 4 procedures yielded a calibration for RUP content of silages with an R2 of 0.84 and a standard error of calibration of 1.55 g/10(-1) kg of CP. In trial 5, the equation was tested on 300 silage samples. The mean predicted RUP content was 21.8 g/10(-1) kg of CP. Data suggest near-infrared reflectance spectroscopy can predict RUP content of silages.     

Short communication: Comparison of protocols to estimate twenty-four-hour fat and protein percentages for herds with a robotic milking system

Currently, different protocols are used in various countries to estimate the 24-h fat and protein percentages for dairy cows that are milked with an automatic milking system. These protocols include estimating 24-h fat and protein percentages from 1) single samples from all animals in the herd; 2) single samples of fat adjusted for covariates and single samples of protein unadjusted for covariates; or 3) all samples (adjusted and unadjusted) collected on test days where test days vary in length from 10 to 18 h. The accuracy of estimated component percentages in predicting observed percentages was determined via agreement analysis for four protocols. Analysis of the data suggests collecting all samples (unadjusted for covariates) during a sampling period of at least 16 h on test day to be the most accurate protocol when estimating 24-h fat and protein percentages in herds with automatic milking systems.     

Short communication: Muscle protein synthetic response to microparticulated whey protein in middle-aged men

Whey protein concentrate (WPC) is a high-quality dairy ingredient that is often included in formulated food products designed to stimulate muscle anabolism. Whey protein concentrate can be affected by UHT processing, and its sensory properties are not compatible with some formulated food products. Microparticulated WPC (mWPC) is a novel ingredient that is resistant to heat treatment and has enhanced sensory properties. When 16 healthy middle-aged men consumed 20 g of either WPC or mWPC, both proteins increased plasma essential AA and leucine concentrations with no detectable difference in curve kinetics. Myofibrillar protein synthesis was increased in both groups for 90 min after ingestion with no difference between groups. Ingestion of mWPC resulted in a muscle anabolic response that was equivalent to that of WPC over the full 210-min measurement period. Formulated products incorporating mWPC or standard WPC would provoke equivalent anabolic responses.     

Short communication: effect of tannic acid on composition and ruminal degradability of bermudagrass and alfalfa silages

We measured the effects of the addition of tannic acid on chemical composition and crude protein (CP) ruminal degradability of bermudagrass, cv. coast cross (Cynodon dactylon L.) and alfalfa (Medicago sativa L.) silages with nylon bags incubated in the rumen of two fistulated lactating cows. Silage pH was greater for alfalfa than for bermudagrass. The addition of tannic acid had no effect on silage pH. Ammonia N was greater in alfalfa than in bermudagrass silage. Treated and control silages had similar ammonia N concentrations. The percentage of CP that was solubilized at time 0 was lower for alfalfa than for bermudagrass silage. The addition of tannic acid decreased the portion of CP solubilized at time 0 and increased the potentially degradable fraction of CP. The potentially degradable fraction of CP was greater for alfalfa than for bermudagrass. There was an interaction of species and treatment; the disappearance rate of CP increased with tannic acid treatment of alfalfa but decreased with acid treatment of bermudagrass. The effective degradability of CP was similar for control and treated alfalfa but lower for treated than for control bermudagrass. Tannic acid treatment is effective in decreasing the rapidly soluble fraction of alfalfa and bermudagrass silages, which could be beneficial to the animal because it would decrease the excess of N in the rumen after feeding. Tannic acid treatment decreased CP degradability of bermudagrass silage but had no effect on alfalfa silage, suggesting that tannic acid concentration required to effectively decrease CP degradability differs among forages.     

Supplementation of cows grazing tropical grass swards with concentrates varying in protein level and degradability

Twelve Holstein and Brown Swiss cows participated in a replicated and balanced 3 x 3 Latin square experiment with 4-wk periods to test three commercial concentrate feeds as supplements to grazing at 4 cows/ha on mixed grass herbage of 6.94% mean CP. Available herbage DM was estimated at 27.5, 21.7, and 15.1 kg/cow per d in successive periods. Excessive rainfall had adverse effects in periods 2 and 3. Treatments were concentrates with 18, 15, or 15% CP with Protek (protein treated by a propietary process) as fed. Mean overall results were daily concentrate intake, 7.44 +/- 1.37 kg; daily milk yield, 17.3 +/- 4.8 kg: percentages of milk fat, SNF, and protein, 3.18 +/- .80, 8.58 +/- .28, and 2.94 +/- .27; FCM per concentrate DM, 2.33 +/- .41; and daily BW loss, .28 +/- .53 kg. Differences among treatments were small and unimportant. Concentrate allowances were intended to satisfy NE1 needs, but the anticipated contribution from pasture was overestimated. Energy rather than protein was deemed first limiting to animal performance, and neither CP higher than 15% in the concentrate nor protein protection was useful under these conditions.     

Short communication: Effects of feeding level on energy concentration in grass silage-based diets offered to dairy cattle

Twelve grass silages were offered to sheep as a sole diet at maintenance and to lactating dairy cows ad libitum as mixed silage and concentrates diets (n = 13 diets). Fecal and urinary energy outputs were measured for silages and mixed diets. Digestible energy (DE) and metabolizable energy (ME) concentrations for mixed diets with sheep at maintenance were estimated based on the silage dry matter (DM) proportion obtained in the cattle trials, the silage energy utilization values (methane energy-predicted) determined using sheep, and tabulated concentrate values. A comparison of dietary mean data (n = 13) indicated that concentrations of ME (P < 0.01) and DE (P < 0.001) in mixed diets were significantly lower for cows at production feeding level than for sheep at maintenance. The reductions were proportionately 0.015 and 0.020 with each unit increase in feeding level above maintenance, respectively. These ME and DE data were also used to evaluate the feeding level correction factors previously proposed by Van Es (1975) (ME, 0.018) and Yan et al. (2002) (ME, 0.016; DE, 0.025) using the mean square prediction error technique. The ME correction factor proposed by Yan et al. (2002) had a greater prediction accuracy than that proposed by Van Es (1975) for the prediction of ME concentration in mixed diets offered to dairy cattle at production feeding level.     

Short communication: Absorption of protein and immunoglobulin g in calves fed a colostrum replacer

A well-managed colostrum program on farms is the most important step in reducing disease in neonatal calves. In the last few years, colostrum replacers have increased in popularity and are designed to be an alternative to colostrum on farms that have poor colostrum quality, limited colostrum reserves, or to break the cycle of transmission for certain infectious diseases. However, it is important to make sure these products are effective and are capable of providing adequate serum immunoglobulin concentrations. The objective of this study was to evaluate the efficacy of a commercially available colostrum replacer product in dairy calves. Holstein calves from a single dairy were randomly assigned to 1 of 3 groups at birth. Group 1 (n = 21) calves were given 4 quarts of colostrum via esophageal feeder within 3 h of birth and served as the control group for this study. Group 2 (n = 21) received 2 packages of a colostrum replacer product, and group 3 (n = 21) received 3 packages of the colostrum replacer product within 3 h of birth. Blood samples from all calves were collected 24 h after colostrum administration and analyzed for serum total protein and IgG concentrations. Calves fed fresh colostrum had significantly higher serum total protein levels and IgG concentrations compared with calves fed the colostrum replacer product. Calves fed the colostrum replacer also had a significantly higher percentage of calves with failure of passive transfer (serum IgG <1,000 mg/dL). The colostrum replacer product evaluated in this study failed to routinely provide adequate IgG concentrations when fed according to label directions.     

Short communication: Determination of the whey protein index in milk protein concentrates

Milk protein concentrates are common ingredients in the dairy industry, with varying processing histories and composition. The objective of this research was to determine the feasibility of using the whey protein nitrogen (WPN) index, a well-established index for skim milk powder and nonfat dry milk, as a quality parameter for milk protein concentrates. The WPN index is a value based on the moisture-adjusted weight of skim milk powder. We hypothesized that WPN, even when standardized based on protein, may change depending on solubilization conditions of milk protein concentrates because of differences in solubilization conditions or processing history. The WPN was measured for model concentrates with different thermal history or reconstitution conditions. The WPN was not affected by an increased concentration of soluble casein in the dispersions nor after solubilization of the powder at 22 or 60°C. All reconstituted samples were standardized for protein. The WPN was also in full accordance with residual native protein measured by chromatography.     

Short communication: Ability of cultured mammary epithelial cells in a bicameral system to secrete milk fat

Mammary epithelial cells from lactating cows were cultured onto inserts coated with type I collagen. Every second day, the rates of fatty acid synthesis and secretion were determined by measuring the amount of [¹⁴C]-labeled sodium acetate incorporated into lipids over a 4-h period. The [¹⁴C]-containing lipids were identified by thin layer chromatography fractionation. In parallel, the integrity of the cell layer was evaluated by measurement of transepithelial electrical resistance. The integrity increased progressively to reach a maximum after 8 d of culture. Cells incorporated acetate into lipids; 1.34% of acetate was incorporated into lipids produced by freshly isolated cells. This percentage decreased to 0.5% after 2 d of culture. Moreover, this capacity decreased with the duration in culture; on d 8, the rate of incorporation dropped to about 3% of that on d 2. In the cell extracts, the [¹⁴C]-labeled lipids were mainly triglycerides, although the proportion of diglycerides and phospholipids progressively increased as a part of total newly synthesized lipids. The proportion of triglycerides decreased 0.66 times between d 2 and 8 when the proportion of diglycerides and phospholipids increased 1.33 and 2.18 times, respectively. About 28% of the newly synthesized lipids were secreted within 4 h of incubation. Around 65 to 85% of these labeled lipids were found in the apical compartment, suggesting a partially vectorial secretion. But 58 to 80% of labeled lipids found in the apical and basolateral medium were free fatty acids. Functional tight junctions and incorporation of labeled fatty acids into triglycerides are not compatible with an inferred status of complete dedifferentiation of the cell layer. Moreover, triglyceride secretion seems compromised, probably due to the lack of an appropriate cell environment and cell shape.     

Prediction of laboratory and in situ protein fractions in legume and grass silages using near-infrared reflectance spectroscopy

Legume and grass silage samples (n = 121) were collected from commercial forage testing laboratories (trial 1). Samples were dried at 55 degrees C for 48 h, ground, scanned on a near-infrared reflectance spectrophotometer, and analyzed for crude protein (CP), soluble CP, acid detergent fiber (ADF) CP, and neutral detergent fiber (NDF) CP by wet chemistry methods. Sixty samples were selected for calibration development, and the remaining samples were used for equation validation. Near-infrared reflectance spectroscopy accurately predicted the CP content of the silages (R2 = 0.96), but prediction of soluble CP, ADF CP, and NDF CP was markedly less accurate. The coefficients of determination and standard errors of calibration for CP, ADF CP, NDF CP (percentage of DM), and soluble CP (percentage of CP) were as follows (0.96 and 0.80, 0.77 and 0.24, 0.72 and 0.71, and 0.82 and 4.40). In a second study, legume and grass silage samples (n = 32) were dried at 55 degrees C and ground (2 mm). Duplicate dacron bags containing 5 g of silage were incubated in the ventral rumen of three ruminally cannulated cows for 0, 3, 6, 12, 24, 48, and 72 h. In situ protein fractions, including rapidly degraded protein, slowly degraded protein, undegradable protein, degradation rate, and rumen-undegradable protein, were determined. Original samples were reground (1 mm) and scanned. Previously defined near-infrared spectroscopy calibration procedures were conducted. Coefficients of determination for in situ CP fractions were R2 > 0.92 with the exception of degradation rate (R2 = 0.87). Data suggest that in situ protein fractions are better predicted by near-infrared reflectance spectroscopy than by laboratory protein fractions.     

Short communication: estimate of non electrostatic interaction free energy parameters for milk fat globules

The surface free energy components for bovine milk fat globules (MFG) were calculated by solving a modified Young-Good-Fowkes-Girafalco equation with experimentally obtained contact angles for liquids of known surface tension components. The surface free energy of MFG was dominated by the electron donor term (gamma-), which formed the basis of a significant repulsive acid-base interaction free energy term at the minimum equilibrium distance. Consideration of the decay of the acid-base and Lifshitz-van der Waals energy term over distance within the context of an "extended DLVO" model shows that physical contact of MFG in the absence of electrostatic repulsion (at their isoelectric point) is prohibited by the acid-base term but that "pseudo-flocculation" might occur at 4- to 5-nm separation in an energy minimum that was approximately 15 kT for MFG of diameter = 1.0 microm.     

Short communication: serum immunoglobulin G and total protein concentrations in dairy calves fed a colostrum-replacement product

Neonatal calf health is largely dependent on the ingestion and absorption of maternally derived antibodies via colostrum administration. The objective of this study was to evaluate the efficacy of a commercially available plasma-derived colostrum-replacement (CR) product as compared with bovine colostrum. Holstein calves were removed from the dam immediately after birth and randomly allocated to 1 of 3 groups. Group 1 calves (n = 22) were fed 1 package of the CR product; group 2 calves (n = 22) were fed 2 packages of the CR product; and group 3 calves (n = 22) were fed 3 L of bovine colostrum. Blood samples were collected from all calves 24 h after colostrum or CR feeding and analyzed for serum IgG and total protein concentrations. Calves fed bovine colostrum had significantly higher serum IgG and total protein concentration than calves in either group fed the CR product. Group 1 calves (1 package of CR product) had a significantly higher incidence of failure of transfer of passive immunity than calves in groups 2 or 3. The results of this study indicated that 2 packages of this CR product achieved adequate IgG concentrations in calves. However, calves fed 1 package of this CR product consistently had failure of transfer of passive immunity.     

Short communication: A reproductive tract scoring system to manage fertility in lactating dairy cows

We developed a reproductive tract size and position score (SPS) system as a reproductive management tool to identify lactating dairy cows with decreased fertility. This system, relying solely on transrectal palpation, considers the size (cervical and uterine) and position of the reproductive tract relative to the pelvis. Cows undergoing pre-breeding exams were identified as having reproductive tracts that were small (SPS1), medium (SPS2), or large (SPS3). Cows designated SPS1 had small and compact uterine horns that rested within the pelvic cavity; SPS2 cows had reproductive tracts that were intermediate in cervical and uterine horn diameter, with longer uterine horns resting partially outside the pelvic cavity; and SPS3 cows had reproductive tracts that were larger and rested mostly outside the pelvic cavity. Cows that were SPS1 had a higher rate of pregnancy per artificial insemination (43.3 ± 3.7%) than cows that were SPS2 (36.9 ± 3.6%) or SPS3 (27.7 ± 4.3%). The percentage of cows with an SPS2 score differed in pregnancies per artificial insemination compared with SPS3 cows. The average days in milk was similar for SPS1, SPS2, and SPS3 cows (104.3 ± 3.5, 98.4 ± 3.4, and 94.7 ± 7.7, respectively). Ultrasound measurements of the uterine horn and cervical diameter, and length measurements of the uterine horns, cervix, and vagina confirmed differences among the SPS groups derived by transrectal palpation. The ease with which transrectal palpation can be used to determine the size and position of the reproductive tract attests to the relevance and usefulness of this scoring system to identify less fertile lactating dairy cows. The ability to do so with ease provides an opportunity to make economically relevant management decisions and maximize reproductive efficiency in a given herd.     

Nutrient composition and the use of solubility to estimate rumen degradability of food proteins in cattle

The use of protein solubility to estimate protein degradability in cattle was tested using 12 by‐products representing agricultural and distillers' food raw materials (RM). Agricultural RM included cereals (rice bran, maize gluten feed), legumes (field beans, soybean hulls) and oil‐seeds (rape meal, sunflower meal). Distillers' RM involved dark grains (DG1, DG2, DG3) and malts (MT1, MT2, MT3). Soluble proteins, as proportions of total soluble N (TSN), were extracted from RM and their undegraded residues (RU) after 18 h of in sacco rumen incubation in cattle (dg₁₈) by using water (albumin), salt (globulin), acid (glutalin 1) and alkali (glutalin 2) in succession. RM and RU differed significantly for all soluble proteins (P < 0.001). While albumin was the major protein in legume RM (0.74TSN), glutalin 1 was the major protein in legume RU (0.54TSN). Cereals were the most variable group, where maize gluten contained five times more albumin and two times more TSN in RM and three times more glutalin 1 + 2 in RU than those in rice bran. Distillers' RM contained slightly less albumin (0.53 vs 0.56TSN) but over twice as much glutalin 1 (0.29 vs 0.12TSN) as agricultural RM. Albumins were the most (0.55TSN, RM; 0.16TSN, RU) and glutalin 1 the least (0.21TSN, RM; 0.48TSN, RU) degradable proteins. There were moderate to strong correlations between protein solubility, dg₁₈ and acid detergent‐insoluble N (ADIN). ADIN correlated satisfactorily with glutalin 1 + 2 (r = ?0.55, RM and ?0.70, RU), TSN (r = ?0.75, RM and RU) and slowly degradable N, (SDN; r = ?0.70, all). TSN in all RM related well with SDN (r = 0.65) and dUN (r = 0.72). TSN in distillers' RM correlated closely with SDN (r = 0.91) and dUN (r = 0.96). Glutalin 1 in distillers' foods correlated extremely well (r = 0.94, RM and 0.93, RU) with dUN. Globulins correlated most consistently with SDN (r = 0.82, all; r = 0.77, agricultural; r = 0.92, distillers' RM). It is possible to predict protein degradability from the presence or absence of soluble proteins in various foods. While ADIN may be more suitable to predict DUN, globulins showed more potential to predict SDN in various foods. However, it may be necessary to be selective in choosing solvents for various foods. Further studies must validate this method by using a greater range of foods before suggesting its routine use for food evaluation. © 2001 Society of Chemical Industry     

Short communication: Validation of a novel milk progesterone-based tool to monitor luteolysis in dairy cows using cost-effective,on-farm measured data

The progesterone (P4) monitoring algorithm using synergistic control (PMASC) uses luteal dynamics to identify fertility events in dairy cows. This algorithm employs a combination of mathematical functions describing the increasing and decreasing P4 concentrations during the development and regression of the corpus luteum and a statistical control chart that allows identification of luteolysis. The mathematical model combines sigmoidal functions from which the cycle characteristics can be calculated. Both the moment at which luteolysis is detected and confirmed by PMASC, as well as the model features themselves, can be used to inform the farmer on the fertility status of the cows.     

Short communication: Labeling Listeria with anaerobic fluorescent protein for food safety studies

Many food safety-related studies require the tracking of inoculated food-borne pathogens to monitor their fate in food complex environments. In the current study, we demonstrate the potential of plasmids containing the fluorescence protein gene evoglow-Pp1 (Evocatal, Dusseldorf, Germany) as a real-time reporter system for Listeria strains. This anaerobic fluorescent protein provides an easily detectable phenotype of microorganisms for food safety studies. This work is the first to report a reliable method to identify fluorescently labeled Listeria strains in food ecosystems.     

Short communication: Evaluation of the efficacy of novel disbudding methods for dairy calves

The objectives of this study were to (1) evaluate whether cryoablation or the administration of clove oil was as efficacious as cautery disbudding at preventing horn growth, and (2) evaluate whether the efficacy of cautery disbudding is affected by removing or leaving the horn bud tissue intact after disbudding of dairy calves. At approximately 4 d of age (4.0 ± 0.88 d of age, mean ± SD), 265 dairy heifer calves from 3 dairy farms (farm 1: n = 129 calves; farm 2: n = 109 calves; farm 3: n = 27 calves) were disbudded. Each calf had 1 of 4 treatments randomly assigned to each horn bud: (1) clove oil (0.5 mL) administered subcutaneously under the horn bud (CLOV, n = 135 buds); (2) a liquid nitrogen–filled probe applied to the horn bud area for 30 s (CRYO, n = 134 buds); (3) cautery disbudding using an electric hot-iron and the horn bud removed (BUDOFF, n = 130); or (4) cautery disbudding and the horn bud tissue left intact (BUDON, n = 131). Calves were assessed for signs of infection at the disbudding site frequently within the first month after disbudding. At approximately 6 mo of age (6 ± 2.2 mo, mean ± SD) calves were assessed for scur or horn growth. The disbudding procedures were considered successful if no scur or horn development was observed. Within the first month, 12% of disbudding wounds showed some indication of infection, such as pus, exudate, or swelling; of the infected buds, 52% were associated with the BUDON treatment, 27% with CLOV, 25% with BUDOFF, and 2% with CRYO treatments. At 6 mo of age, BUDOFF was the most effective method of preventing horn growth and CRYO was the least efficacious [mean percentage of success: BUDOFF: 100% (95% CI: 97.7–100.0); CRYO: 1% (95% CI: 0.2–5.3)]. Injecting clove oil under the horn bud was 87% (95% CI: 80.6–92.5) successful. Not removing the horn bud tissue after cautery disbudding reduced the efficacy of this method by 9% [91% success (95% CI: 83.8–95.7)]; moreover, this method was associated with more infection at the site of disbudding. It appears as though the clove oil treatment could be used as an alternative to cautery disbudding of dairy calves; however, further research is needed to evaluate the tissue damage and associated pain caused by clove oil and to refine this technique (i.e., administration methods to improve efficacy) before it could be considered an alternative to cautery.     

Short communication: Detection of stx2 and elt genes in bovine milk by using a multiplex PCR system

The aim of this study was to detect 2 important toxin genes from diarrheagenic Escherichia coli (DEC) in bovine milk using a new multiplex PCR. To standardize the multiplex PCR, the stx2 and elt genes were investigated for the detection of Shiga toxin-producing Escherichia coli (STEC) and enterotoxigenic E. coli (ETEC), respectively. The DNA template was prepared with a thermal procedure (boiling) and a commercial kit. Samples consisted of UHT and pasteurized milk, both skimmed, and STEC and ETEC were tested in concentrations between 10¹ and 10⁹ cfu/mL. With the thermal procedure, the multiplex PCR system detected both pathotypes of E. coli at 10⁹ cfu/mL in UHT and pasteurized milk. When the commercial kit was used for template preparation, STEC and ETEC could be detected at concentrations as low as 10⁴ cfu/mL in UHT and pasteurized milk. Negative controls (Listeria monocytogenes, Salmonella Typhimurium, Salmonella Enteritidis, and Escherichia coli strain APEC 13) were not amplified with the multiplex PCR. These results indicate that the multiplex PCR was a rapid (less than 6 h) and efficient method to detect STEC and ETEC in milk using different methods for DNA preparation; however, the commercial kit was more sensitive than the thermal procedure.     

Short communication: Effect of dietary protein on growth and nitrogen balance of Holstein heifers

A growth study and a companion N balance study were conducted to evaluate the effect of dietary protein on growth and N utilization of postpubertal Holstein heifers. Forty heifers (398 +/- 9.4 kg) were fed one of four diets containing 8, 11, 13, or 15% crude protein (CP) for 121 d. Body measurements were taken at the beginning and end of the experimental period. Blood was collected via jugular vein every 28 d and evaluated for serum protein, albumin, and urea nitrogen. Curvilinear relationships were observed between dietary CP and gains in wither height and hip width, with maximal gains occurring at 13% CP. Feeding heifers higher amounts of dietary CP resulted in linear increases in heart girth gain, serum protein, albumin, and blood urea nitrogen. In the companion N balance study, feeding increasing amounts of dietary CP to heifers resulted in linear increases in N intake, fecal-N, urinary-N, and absorbed-N. There was a numerical trend towards maximal N retention in heifers fed diets containing 13% CP. Curvilinear relationships also were observed between dietary CP and dry matter, organic matter, and CP digestibility with maximal nutrient digestibilities occurring when heifers were fed diets containing 13% CP. Data suggest 13% dietary CP was optimal for postpubertal (400 kg) Holstein heifers.