Estimates of calf starter energy affected by consumption of nutrients. 1. Evaluation of models to predict changing digestion on energy content in calf starters

Apparent total-tract digestibility data from 3 published studies with calves from 0 to 4 mo of age were used to evaluate National Research Council (2001) estimates of metabolizable energy (ME) in calf starters (CS). Calves (n = 83) or pens of calves (n = 24) were used in model development. In each study, 48 Holstein bull calves (2 to 3 d of age at initiation of each study) were fed varying amounts of milk replacer with CS and water for ad libitum consumption. Calf starters varied in nutrient content and form (pelleted, texturized, or mixed with 5% grass hay and fed as a total mixed ration). Apparent total-tract digestibility was measured at various ages from 3 to 16 wk. Feed and feces were collected from 20 calves per trial during 5-d collection periods during the first 56 d of each trial. In 2 studies, calves were grouped in pens (4 calves/pen) for a second 56-d measurement period. Fecal collections were repeated occasionally during the second period. Total-tract digestibilities (n = 207) of neutral detergent fiber, nonfiber carbohydrates, crude protein, and fat were used to calculate digestible energy (DE) and ME in CS using equations from the 2001 Dairy National Research Council. Three modeling approaches were constructed to evaluate changing digestion of nutrients, DE, and ME in CS, including linear mixed models, broken-line regression, and exponential models. Linear mixed models provided best model fit statistics for digestion of crude protein, ether extract, neutral detergent fiber, and ME. Exponential models were optimal for digestion of dry matter and nonfiber carbohydrates. Linear mixed models were selected for evaluation of effects of intake on changing nutrient digestion from CS and amount of DE and ME available at various ages.     

Symposium review: Re-evaluation of National Research Council energy estimates in calf starters

Provision of nutrients in appropriate amounts to meet nutrient requirements for growth, production, and reproduction is the basis for modern animal nutrition. Ration formulation systems predict nutrient requirements based on numerous inputs and then predict nutrient supply based on predicted intake and nutrient content of feeds. Energy systems are used to predict energy supply based on gross caloric content of feeds followed by adjustments for digestion and metabolism of ingested energy. Many models of energy supply use static coefficients of digestibility based on nutrient composition of feed. Other models partition digestion dynamically between ruminal and postruminal digestion but use static estimates of intestinal digestibility to predict energy supplied to the animal. In young calves, both ruminal fermentation and intestinal digestion are underdeveloped; therefore, existing models of energy supply might overestimate the energy available before complete gastrointestinal maturation. In a series of experiments, we reported that total-tract digestion of nutrients changes with advancing age and nutrient intake. Total-tract digestion was measured in calves from 3 to 16 wk of age when fed different amounts and types of milk replacers. Calves were also fed different types of calf starter for ad libitum consumption. Total-tract digestibility of protein, fat, neutral detergent fiber, and nonfiber carbohydrate (NFC) was used to calculate the metabolizable energy (ME) in starter. We used nonlinear regression to estimate the contribution of protein and fat from starter and milk replacer before weaning. Early in life, calculated ME of starter was low and increased with increasing intake of NFC. Cumulative intake of NFC was more highly correlated with changing ME values than other indices, including age, intake of milk replacer, or intake of other nutrients in starter. When calves consumed at least of 15 kg of NFC, ME calculated from digestibility measurements was similar to the ME calculated using National Research Council equations and indicated maturation of gastrointestinal digestion. Our data suggest that intake of NFC is critical to gastrointestinal maturation and the calf's ability to extract energy from calf starter.     

Effects of including corn distillers dried grains with solubles in dairy calf feeds

A series of 5 trials was conducted to determine the effect of distillers dried grains with solubles (DG) in calf diets. Trial 1 compared 0 or 49% DG in 18% crude protein (CP) starters (as-fed basis) fed to calves initially 2 to 3 d old for 56 d. Digestibility was estimated during d 52 to 56 using chromic oxide. Trial 2 compared 0 or 39% DG in 16% CP growers fed to calves from 8 to 12 wk of age from 28 d. Trial 3 compared 0, 10, or 20% DG in 18% CP starters fed to calves initially 2 to 3 d old for 56 d. Trial 4 compared 0 or 20% DG in 16% CP growers fed to calves from 8 to 12 wk of age from 28 d. As DG increased in all diets, acid detergent fiber, neutral detergent fiber, and fat increased and calculated metabolizable energy was similar but not equalized. In trials 1 and 3, calves (n = 48/trial) housed in individual pens were fed 26% CP, 17% fat milk replacer powder and weaned at 28 d. Trials 2 and 4 used calves (n = 48/trial) housed in group pens (6 calves/pen) that had been weaned for 28 d before the trials’ start. Trial 5 (n = 18 calves) had the same starter treatments as trial 3 fed in combination with high or low milk replacer intake, with calves killed at 35 d to determine effects of DG and milk replacer intake on rumen development. In trial 1, average daily gain (ADG) was 6% greater and dry matter digestibility was 10% greater for calves fed 0% versus 49% DG. In trial 2, ADG (9%), feed efficiency (10%), and hip width change (19%) were greater for calves fed 0% versus 39% DG. Performance measures did not differ among starter treatments in Trials 3 and 5. In trial 4, ADG (4%), feed efficiency (5%), and hip width change (19%) were greater for calves fed 0% versus 20% DG. In trial 5, rumen development was not affected by DG inclusion, but was greater for calves fed milk replacer at 630 versus 940 g/d, which had greater starter intake. Overall, we conclude that high levels of distillers in calf starters and growers decrease growth of calves; however, starters with ≤20% DG allow for normal growth rates and rumen development.     

Effects of fat concentration of a high-protein milk replacer on calf performance

The hypothesis was that calves fed high-fat milk replacers (MR) would have reduced starter intake, digestibility, and average daily gain (ADG). Forty-eight Holstein calves (initially 42.4 ± 1.5 kg of body weight, 2 to 3 d of age; 12 calves/treatment) were fed 0.66 kg dry matter (DM) of MR per calf daily that contained 14, 17, 20, or 23% fat. This MR had crude protein (CP) to metabolizable energy (ME) ratios ranging from 51.6 to 56.7 g of CP/Mcal of ME, which were above and below a previously determined optimum. Calves were weaned at 28 d; postweaning measurements were continued to d 56. A 20% CP starter and water were fed ad libitum all 56 d of the trial. Measurements of digestion were made using chromic oxide as a marker in the MR and starter from fecal samples collected on d 19 to 23 from 4 calves/treatment. Selected serum constituents were measured on d 21. Calves were housed individually in pens bedded with straw within a naturally ventilated barn with no added heat. The average barn temperature was 2°C. Data were analyzed as a completely randomized design using polynomial contrasts to separate differences in the means. Preweaning apparent digestibility of DM, organic matter, fat, nonfiber carbohydrates, Ca, and P and serum amylase concentration were linearly reduced as fat increased from 14 to 23%. Preweaning starter intake responded quadratically to fat, being lowest at 14 and 23% fat. A reduction in digestibility and starter intake contributed to less ADG at the higher fat concentrations in the MR. A 27% CP, 17% fat MR with 55 g of CP/Mcal of ME maximized preweaning ADG when fat concentration was varied to obtain various CP to ME ratios in the MR. Additionally, a 27% CP, 20% fat MR with 53 g of CP/Mcal of ME supported overall ADG similar to calves fed the 17% fat MR but preweaning digestion measurements and serum amylase concentrations were less than in calves fed the 17% fat MR.     

Relationships between protein and energy consumed from milk replacer and starter and calf growth and first-lactation production of Holstein dairy cows

The objective was to determine relationships between protein and energy consumed from milk replacer and starter and calf growth and first-lactation production of Holstein heifer calves. Milk replacer and starter protein intake and metabolizable energy (ME) intake data were collected from 4,534 Holstein heifer calves for growth and 3,627 Holstein cows for production from birth year of 2004 through 2014. Calves from 3 commercial dairy farms were assigned to 45 different calf research trials at the University of Minnesota Southern Research and Outreach Center, Waseca, Minnesota, from 3 to 195 d of life. Calves were moved to heifer growers at 6 mo of age, and calves were returned to their farm of birth a few weeks before calving. Most calves (85%) were fed a 20% crude protein and 20% fat milk replacer at a rate of 0.57 kg/calf daily. Metabolizable energy and protein consumed from milk replacer and starter were calculated for each individual calf for 6 and 8 wk of age. Mixed model analyses were conducted to determine the effect of protein and energy consumed from both milk replacer and starter on calf growth and first-lactation 305-d production of milk, fat, and protein, adjusting for herd, season of birth, year, average daily gain (ADG), and calf trial. Calves with ADG >0.80 kg/d consumed more combined protein and ME than calves with lower ADG. Protein and ME intake from calf starter affected growth more than protein and ME intake from milk replacer because most calves were fed the same fixed amount of milk replacer. Calves born during the fall and winter had greater combined protein and ME intake than calves born during the spring and summer. Milk replacer protein and ME intake did not have a relationship with first-lactation 305-d milk, fat, and protein production. However, starter protein and ME intake during the first 6 and 8 wk of age had a significant positive relationship with first-lactation 305-d milk, fat, and protein production. Consequently, combined protein and combined ME intake had a positive effect on 305-d milk, fat, and protein production. Variance in protein and ME intake was high, suggesting that additional factors affect calf growth during the first 8 wk of life and milk production in first lactation.     

Effects of fatty acids and calf starter form on intake,growth, digestion,and selected blood metabolites in male calves from 0 to 4 months of age

The objective of this research was to determine if form of calf starter (CS) and addition of a fatty acid blend (FA) influenced intake, growth, digestion, and indices of immune status and stress in calves from 0 to 4 mo of age. Male Holstein calves [n = 48; 41.9 kg of body weight (BW), standard error = 0.7; 2 to 3 d of age] were assigned to receive reconstituted whole milk powder [0.66 kg of dry matter (DM)/d to 39 d, then 0.33 kg of DM/d to weaning at 42 d] without or with added FA. Calf starters were textured (pellet, whole oats, whole corn) or pelleted and were offered for ad libitum consumption from 0 to 56 d, then blended with 5% chopped grass hay and fed from d 57 to 112. Starters contained 20% crude protein (CP) and 38 to 40% starch in the DM. From d 0 to 56, calves were housed individually. From d 57 to 112, calves were grouped into pens by treatment (n = 4/pen). Form of CS during the initial 56 d had no effect on intake or growth, though days with fluid feces (fecal score ≥2.5) were greater when calves were fed textured CS. Feeding FA during the initial 56-d increased average daily BW gain, gain-to-feed ratio, and change in hip width, and reduced the number of days calves were treated with antibiotics. During d 57 to 112, CS form had no effects on any performance measure. Adding FA to CS increased average daily BW gain and hip width change, and tended to improve efficiency of BW gain. Total-tract digestibility was estimated at 4, 6, and 8 wk with 5 calves per treatment, and at 10, 13, and 16 wk of age using pen (n = 3 per treatment) as the experimental unit. Feeding FA increased or tended to increase total-tract digestion of DM, organic matter, starch, neutral detergent fiber (NDF), acid detergent fiber (ADF), CP, and fat at one or more measurement periods. Calves fed a textured CS increased or tended to increase digestion of DM, organic matter, starch, sugar, NDF, ADF, and CP during wk 6 and 8. However, during the second 56-d phase, feeding textured CS reduced or tended to reduce digestion of DM, organic matter, starch, NDF, ADF, and fat during wk 13 and 16. Inclusion of FA in milk increased serum bactericidal activity before weaning. Serum haptoglobin concentration increased 3 d postweaning when calves were fed textured CS. Feeding FA improved animal health, digestion, and performance. Form of CS had few effects on animal performance.     

Short communication: Effects of increasing protein and energy in the milk replacer with or without direct-fed microbial supplementation on growth and performance of preweaned Holstein calves

Forty-four Holstein calves were fed a direct-fed microbial (DFM) and 1 of 2 milk replacers to evaluate calf performance and growth. Treatments were (1) a control milk replacer [22:20; 22% crude protein (CP) and 20% fat], (2) an accelerated milk replacer (27:10; 27% CP and 10% fat), (3) the control milk replacer with added DFM (22:20+D), and (4) the accelerated milk replacer with added DFM (27:10+D). Dry matter intake, rectal temperatures, respiration scores and rates, and fecal scores were collected daily. Body weight, hip and withers height, heart girth, blood, and rumen fluid samples were collected weekly. Effects of treatment, sex, week, and their interactions were analyzed. Calves fed an accelerated milk replacer, regardless of DFM supplementation, consumed more CP and metabolizable energy in the milk replacer. No treatment differences were found for starter intake or intake of neutral detergent fiber or acid detergent fiber in the starter. Calves fed the accelerated milk replacer had greater preweaning and weaning body weight compared with calves fed the control milk replacer. Average daily gain was greater during the preweaning period for calves fed the accelerated milk replacer, but the same pattern did not hold true during the postweaning period. Feed efficiency did not differ among treatments. Hip height tended to be and withers height and heart girth were greater at weaning for calves fed the accelerated milk replacer compared with calves fed the control milk replacer. Fecal scores were greatest in calves fed DFM. Overall acetate, propionate, butyrate, and n-valerate concentrations were lower in calves fed the accelerated milk replacer, but DFM did not have an effect. Rumen pH was not different. Blood metabolites were unaffected by DFM supplementation, but calves fed the accelerated milk replacer had increased partial pressure of CO₂, bicarbonate, and total bicarbonate in the blood. Direct-fed microbial supplementation did not appear to benefit the calf in this trial     

Evaluation of the National Research Council (2001) dairy model and derivation of new prediction equations. 1. Digestibility of fiber,fat, protein,and nonfiber carbohydrate

Evaluation of ration balancing systems such as the National Research Council (NRC) Nutrient Requirements series is important for improving predictions of animal nutrient requirements and advancing feeding strategies. This work used a literature data set (n = 550) to evaluate predictions of total-tract digested neutral detergent fiber (NDF), fatty acid (FA), crude protein (CP), and nonfiber carbohydrate (NFC) estimated by the NRC (2001) dairy model. Mean biases suggested that the NRC (2001) lactating cow model overestimated true FA and CP digestibility by 26 and 7%, respectively, and under-predicted NDF digestibility by 16%. All NRC (2001) estimates had notable mean and slope biases and large root mean squared prediction error (RMSPE), and concordance (CCC) ranged from poor to good. Predicting NDF digestibility with independent equations for legumes, corn silage, other forages, and nonforage feeds improved CCC (0.85 vs. 0.76) compared with the re-derived NRC (2001) equation form (NRC equation with parameter estimates re-derived against this data set). Separate FA digestion coefficients were derived for different fat supplements (animal fats, oils, and other fat types) and for the basal diet. This equation returned improved (from 0.76 to 0.94) CCC compared with the re-derived NRC (2001) equation form. Unique CP digestibility equations were derived for forages, animal protein feeds, plant protein feeds, and other feeds, which improved CCC compared with the re-derived NRC (2001) equation form (0.74 to 0.85). New NFC digestibility coefficients were derived for grain-specific starch digestibilities, with residual organic matter assumed to be 98% digestible. A Monte Carlo cross-validation was performed to evaluate repeatability of model fit. In this procedure, data were randomly subsetted 500 times into derivation (60%) and evaluation (40%) data sets, and equations were derived using the derivation data and then evaluated against the independent evaluation data. Models derived with random study effects demonstrated poor repeatability of fit in independent evaluation. Similar equations derived without random study effects showed improved fit against independent data and little evidence of biased parameter estimates associated with failure to include study effects. The equations derived in this analysis provide interesting insight into how NDF, starch, FA, and CP digestibilities are affected by intake, feed type, and diet composition.     

Canola meal or soybean meal as protein source and the effect of microencapsulated sodium butyrate supplementation in calf starter mixture. I. Performance,digestibility, and selected blood variables

Two studies were conducted to assess the effect of protein source and microencapsulated sodium butyrate (MSB) inclusion in pelleted starter mixtures on growth performance, gain to feed (G:F) ratio, nutrient digestibility, and selected blood metabolites in calves. In study 1, 28 Holstein bull calves (8.7 ± 0.8 d of age and 43.0 ± 4.4 kg; mean ± SD) were allocated to 1 of 4 treatments in a 2 × 2 factorial arrangement and fed a pelleted starter mixture containing canola meal (CM, 35% as fed) or soybean meal (SM, 24% as fed) as the main source of protein, with or without supplemental MSB (0.3% as fed). Starter mixtures were formulated to be similar for crude protein, Lys, and Met, and were fed ad libitum. Calves were weaned after 42 d of milk replacer feeding (51.7 ± 0.8 d of age) and observed for another 21 d. Furthermore, selected blood metabolites were measured on d 21, 42, and 63 of the study, and nutrient digestibility was measured after weaning. In study 2, 60 Holstein heifer calves (9.1 ± 0.8 d of age and 43.2 ± 4.2 kg) were assigned to the same treatments as in study 1. The calves were weaned after 49 d of milk replacer feeding (59.1 ± 0.8 d of age) and observed for an additional 14 d. Milk replacer and starter mixture intake and fecal score were recorded daily, whereas body weight (BW) was recorded weekly. In study 1, calves fed starter mixtures containing CM had or tended to have lesser preweaning starter intake, weaning average daily gain (ADG), weaning and overall G:F ratio, and postweaning total-tract dry matter digestibility, as opposed to those fed starter mixtures with SM. However, these differences did not affect overall starter intake, overall ADG, or final BW. Supplementation with MSB only tended to increase the preweaning starter mixture intake. In study 2, heifer calves that were fed starter mixtures with CM had greater cumulative starter intake after weaning, but the protein source in the starter mixture had no effect on ADG, BW, or G:F ratio. Inclusion of MSB in starter mixtures for calves tended to decrease postweaning starter mixture intake. In conclusion, use of CM or SM as the main source of protein in starter mixture resulted in similar growth performance of bull and heifer calves; however, CM use in starter mixtures reduced starter intake, ADG, and G:F ratio at least at some points of rearing. Supplementation of MSB had minor effects on the growth performance of calves.     

Influence of starter protein content on growth of dairy calves in an enhanced early nutrition program

Our objectives were to determine the effect of starter crude protein (CP) content on growth of Holstein calves from birth to 10 wk of age in an enhanced early nutrition program, and to compare the enhanced program to a conventional milk replacer program. Calves (64 female, 25 male) were assigned to 3 treatments in a randomized block design: 1) conventional milk replacer (20% CP, 20% fat) plus conventional starter [19.6% CP, dry matter (DM) basis], 2) enhanced milk replacer (28.5% CP, 15% fat) plus conventional starter, and 3) enhanced milk replacer plus high-CP starter (25.5% CP, DM basis). Calves began treatments (n=29, 31, and 29 for treatments 1 to 3) at 3 d of age. Conventional milk replacer (12.5% solids) was fed at 1.25% of birth body weight (BW) as DM daily in 2 feedings from wk 1 to 5 and at 0.625% of birth BW once daily during wk 6. Enhanced milk replacer (15% solids) was fed at 1.5% of BW as DM during wk 1 and 2% of BW as DM during wk 2 to 5, divided into 2 daily feedings. During wk 6, enhanced milk replacer was fed at 1% of BW as DM once daily. Calves were weaned at d 42. Starter was available for ad libitum intake starting on d 3. Starter intake was greater for calves fed conventional milk replacer. For calves fed enhanced milk replacer, starter intake tended to be greater for calves fed enhanced starter. During the weaning period, enhanced starter promoted greater starter DM intake than the conventional starter. Over the 10-wk study, the average daily gain of BW (0.64, 0.74, and 0.80 kg/d) was greater for calves fed enhanced milk replacer with either starter and, for calves fed enhanced milk replacer, tended to be greater for calves fed high-CP starter. Rates of change in withers height, body length, and heart girth were greater for calves fed enhanced milk replacer but did not differ between starter CP concentrations. The postweaning BW for enhanced milk replacer treatments was greater for calves receiving the enhanced starter at wk 8 (73.7, 81.3, and 85.8 kg) and wk 10 (88.0, 94.9, and 99.9 kg). Starter CP content did not affect height, length, or heart girth within enhanced milk replacer treatments. Regression analysis showed that gain of BW during the first week postweaning (wk 7) increased with greater 3-d mean starter intake in the week before weaning. Starter with 25.5% CP (DM basis) provided modest benefits in starter intake (particularly around weaning) and growth for dairy calves in an enhanced early nutrition program compared with a conventional starter (19.6% CP).     

Effect of increasing energy and protein intake on body growth and carcass composition of heifer calves

The objective was to determine whether increased energy and protein intake between 2 and 14 wk of age would increase growth rates of heifer calves without fattening. At 2 wk of age, Holstein heifer calves were assigned to 1 of 4 treatments in a 2 x 2 factorial arrangement with 2 levels of protein and energy intake (moderate [M]; high [H]) in period 1 (2 to 8 wk of age) by 2 levels of protein and energy intake (low [L]; high [H]) in period 2 (8 to 14 wk of age) to produce similar initial BW for all 4 treatments. Treatments were ML, MH, HL, and HH, indicating moderate or high energy and protein intake during the first period and low or high intake during the second period. The M diet consisted of a standard milk replacer (21.3% CP, 21.3% fat) fed at 1.1% of BW on a DM basis and a 16.5% CP grain mix fed at restricted intake to promote 400 g of average daily gain (ADG), whereas the L diet consisted only of the grain mix. The H diet consisted of a high-protein milk replacer (30.3% CP, 15.9% fat) fed at 2% of BW on a DM basis and a 21.3% CP grain mix available ad libitum. Calves were weaned gradually from milk replacer by 7 wk and slaughtered at 8 (n = 11) or 14 wk of age (n = 41). In periods 1 and 2, ADG and the gain:feed ratio were greater for calves fed the H diet. Calves fed the H diet were taller after both periods 1 and 2. No difference was observed in carcass composition at 8 wk, but at 14 wk calves fed MH and HH had less water and more fat than calves fed ML and HL. Plasma IGF-I concentrations were greatest for calves fed the H diet during either period. Plasma leptin concentrations were increased in calves fed the H diet during period 1 from 4 to 6 wk of age. Increasing energy and protein intake from 2 to 8 wk and 8 to 14 wk of age increased BW, withers height, and gain:feed ratio. Calves fed the H diet from 8 to 14 wk of age had more body fat than calves fed the L diet. Increased energy and protein intake can increase the rate of body growth of heifer calves and potentially reduce rearing costs.     

Performance, health, and postweaning growth on calves fed cold, acidified milk replacer ad libitum

Holstein calves were assigned to one of three regimens from d 4 to 35 of age, then abruptly weaned (program 1): A) conventional, all-milk protein milk replacer fed individually twice daily; B) ad libitum feeding of cold, acidified milk replacer to calves housed and fed individually in pens, and C) same as B, except calves were housed and fed in group pens. From d 36 of age to 136 kg of body weight calves were in group pens by treatment. Program 2 utilized the same treatments; however, acidified milk replacer calves were gradually weaned starting d 22 of age. For program 1, calves fed acidified milk replacer for ad libitum intake consumed more dry matter from liquid and less from grain than those fed conventionally. Calves fed acidified milk replacer showed improved gains of 8.7 and 8.4 kg up to d 35 of age. For program 2, dry matter intake from liquid was higher, and grain was lower for calves fed acidified milk replacer; however, differences were not as large as in program 1. Body weight gains were 1.1 and 2.8 kg higher for calves fed acidified milk replacer through d 35 of age. No mortality occurred with either program during preweaning. In both programs, fecal consistency was more fluid for calves fed acidified milk replacer; however, days calves were treated were less. Regardless of preweaning program, calves on all treatments reached 136 kg of body weight in approximately the same number of days.     

Effect of energy source in calf milk replacer on performance,digestibility, and gut permeability in rearing calves

Current calf milk replacer (CMR) compositions significantly differ from whole milk in their levels of energy, protein, and minerals. Energy source is one of the major differences, as CMR contains high levels of lactose, whereas whole milk contains higher levels of fat. The aim of this study was to determine the effect of partially exchanging lactose for fat on performance, digestibility, and gut permeability in calves fed twice daily on a high feeding plane. Lactose and fat were exchanged in the CMR formulation on a weight–weight basis. The CMR were isonitrogenous but not isoenergetic. A total of 60 male Holstein-Friesian calves were assigned to 1 of 30 blocks based on serum IgG, body weight, and date of collection after birth. Within each block, calves were randomly assigned to 1 of 2 treatments: high fat and high lactose. The CMR was provided twice daily until 49 d of age, followed by a gradual weaning period of 14 d. Starter, straw, and water were available ad libitum throughout the complete study. Exchanging lactose for fat did not affect growth; intakes of starter, straw, water, crude protein, or total energy; or apparent total-tract digestibility of nutrients. Gastrointestinal permeability was assessed by measuring the recovery of lactulose and Cr in 24-h urine and the Cr concentration and lactulose:d-mannitol ratio in serum following an oral pulse dose. Urinary recoveries of Cr and lactulose were generally low in both treatments but were higher in calves fed the high-fat CMR. Accordingly, the serum lactulose:d-mannitol ratio and serum Cr concentrations were higher in calves fed the high-fat CMR. In wk 1 and during the weaning transition, calves fed the high-fat CMR had significantly fewer abnormal fecal scores. In conclusion, exchanging lactose for fat in the CMR did not affect growth performance, total feed intake, or nutrient digestibility. The high-fat CMR was associated with an increase in permeability markers but positively influenced fecal scores in calves.     

Effects of the amount of chopped hay or cottonseed hulls in a textured calf starter on young calf performance

Four trials were conducted to compare the concentrations of cottonseed hulls (CSH) and chopped hay in textured starters on calf body weight gain, intake, and efficiency. Holstein bull calves (initially 3 and 4 d old in studies 1, 2, and 3, and 59 to 60 d old in study 4) were fed ad libitum starters (geometric mean particle size of approximately 2,000 22mim; equal at 18% crude protein as-fed; digestible energy concentration declined with increasing roughage). All calves were weaned at 31 to 32 d of age. Calves were housed in individual pens bedded with straw within an unheated, curtain-sided nursery for d 0 to 56 and then grouped in pens of 6 calves for d 56 to 84. Study 1 compared textured starters containing A) 0% or B) 5% CSH for the first 56 d. On d 56 (through d 84), calves fed diet A were switched to diet C, which contained 0% CSH and 5% chopped hay; calves fed diet B were switched to diet D, which contained 5% CSH and 5% hay. Study 2 compared textured starters fed from 0 to 84 d that contained A) 0% CSH and 0% chopped hay, B) 5% CSH, C) 10% CSH, or D) 5% chopped hay. Study 3 compared textured starters fed from 0 to 56 d that contained A) 0%, B) 2.5%, and C) 5% chopped hay. Study 4 compared textured starters fed from d 56 to 84 that contained A) 5% and B) 15% chopped hay. In study 1, calves fed the diet with 5% CSH consumed less starter and were less efficient from 28 to 56 d than calves fed 0% CSH. Calves fed the diet with 0% CSH tended to have a greater average daily gain (ADG) and empty body weight ADG (EBWADG) from 28 to 84 d than calves fed the starter with 5% CSH. In study 2, EBWADG declined linearly from 0 to 28 d, and both ADG and EBWADG decreased from 28 to 56 d as CSH percentage increased in the starter. Both ADG and EBWADG responded quadratically to CSH percentage in the starter from 56 to 84 d, with calves fed the starter containing 10% CSH having the slowest ADG and EBWADG. Calves between 56 and 84 d that were fed starters with 5% roughage appeared more efficient than calves fed starters with 0 or 10% roughage. In study 3, ADG, EBWADG, starter intake, and efficiency declined linearly as hay percentage increased in the starter from 28 to 56 d. In study 4, ADG, EBWADG, and starter intake were less for calves fed starters with 15 vs. 5% hay. In conclusion, adding low-energy fibrous feeds to starters with adequate coarseness (approximately 2,000 μm) reduced ADG in weaned calves less than 3 mo old bedded on straw.     

Effects of additional milk replacer feeding on calf health, growth, and selected blood metabolites in calves

The objective of the experiment was to evaluate effects of increased milk replacer feeding on growth, intake, feed efficiency, and health parameters in stressed calves. Holstein bull calves (n = 120; approximately 3 to 8 d of age) were purchased from sale barns and dairy farms and housed in fiberglass hutches. In addition, wood shavings contaminated with coronavirus were mixed with clean shavings and added to each hutch before the start of the experiment. Calves were fed either a fixed amount (454 g/d) of a 20% crude protein (CP), 20% fat milk replacer to weaning at 28 d or a variable amount (454, 681, 908, and 454 g/d on d 0 to 7, 8 to 14, 15 to 31, and 32 to 41, respectively) of a milk replacer containing 28% CP and 17% fat without or with added dietary supplement containing bovine serum. Calves were also fed commercial calf starter and water ad libitum. Plasma IgG concentration in most calves on arrival at the facility was < 10 g/L. Intake, change in body weight, feed efficiency, morbidity and mortality, and selected plasma metabolites were determined. Body weight at 28 d, 56 d, daily body weight gain, intake of milk replacer, fecal scores, days with diarrhea, and days treated with antibiotics were increased with feeding variable amount of milk replacer over the 56-d study. Starter intake from d 1 to 56 was reduced from 919 to 717 g/d in calves fed fixed and variable amounts of milk replacer, respectively. Morbidity, measured as the number of days that calves had diarrhea, was increased by 53% when a variable amount of milk replacer was fed. Calves fed variable milk replacer were treated with antibiotics for 3.1 d compared with 1.9 d for calves fed 454 g of milk replacer/d. Concentrations of plasma glucose, urea N, and insulin-like growth factor-I were increased when calves were fed variable amount of milk replacer. Dietary supplement containing bovine serum had no effect on any parameter measured. There was no effect of milk replacer feeding on concentrations of nonesterified fatty acids, total protein, or growth hormone concentrations. Plasma tumor necrosis factor-α was highest in calves with the highest plasma IgG concentrations on the day of arrival and might be related to the calf's ability to identify pathogens in the environment. Under conditions of this study, calves fed variable amount of milk replacer and exposed to immunological challenge before weaning had greater BW gain, but also increased incidence of diarrhea that required added veterinary treatments.     

Hot topic: Apparent total-tract nutrient digestibilities measured commercially using 120-hour in vitro indigestible neutral detergent fiber as a marker are related to commercial dairy cattle performance

Measuring individual feed nutrient concentration is common practice for field dairy nutritionists. However, accurately measuring nutrient digestibility and using digestion values in total digestible nutrients models is more challenging. Our objective was to determine if in vivo apparent total-tract nutrient digestibility measured with a practical approach was related to commercial milk production parameters. Total mixed ration and fecal samples were collected from high-producing cows in pens on 39 commercial dairies and analyzed at a commercial feed and forage testing laboratory for nutrient concentration and 120-h indigestible NDF (iNDF) content using the Combs-Goeser in vitro digestion technique. The 120-h iNDF was used as an internal marker to calculate in vivo apparent nutrient digestibilities. Two samples were taken from each dairy and were separated in time by at least 3wk. Samples were targeted to be taken within 7d of Dairy Herd Improvement (DHI) herd testing. Approved DHI testers measured individual cow milk weights as well as fat and protein concentrations. Individual cow records were averaged by pen corresponding to the total mixed ration and fecal samples. Formulated diet and dry matter intake (DMI) records for each respective pen were also collected. Mixed model regression analysis with dairy specified as a random effect was used to relate explanatory variables (diet nutrient concentrations, formulated DMI, in vivo apparent nutrient digestibilities, and fecal nutrient concentrations) to milk production measures. Dry matter intake, organic matter (OM) digestibility, fecal crude protein (CP) concentration, and fecal ether extract concentration were related to milk, energy-corrected milk, and fat yields. Milk protein concentration was related to CP digestibility, and milk protein yield was related to DMI, OM digestibility, CP digestibility, and ether extract digestibility. Although many studies have related DMI and OM digestibility to milk production under controlled experimental settings, very few have related practical in vivo measures to milk production. By documenting the practical OM digestibility relationship with milk production, nutritionists and scientists may have confidence in this approach for measuring diet performance and collecting nutritional data for commercial dairies.     

Effects of mixing a high-fat extruded pellet with a dairy calf starter on performance,feed intake,and digestibility

During weaning, withdrawal of milk replacer is not directly compensated for by an increase in solid feed intake. Therefore, greater fat inclusion in the starter might mitigate this temporary dietary energy decline. However, fat inclusion in solid feeds may generally limit rumen fermentability and development. To address these potentially conflicting outcomes, we conducted 2 experiments to evaluate the effect of supplementing a high-fat extruded pellet mixed with a calf starter on feed intake, performance, and nutrient digestibility in calves. In experiment 1, 60 Holstein bull calves were blocked by serum IgG (2,449 ± 176 mg/dL) and date of arrival (2.5 ± 0.5 d of age). Within each block, calves were randomly assigned to 1 of 3 treatments: a standard control calf starter (CON; 3.1% fat) and mixtures of CON with 10% inclusion of 1 of 2 different high-fat extruded pellets containing 85% of either hydrogenated free palm fatty acids (PFA, 7.1% fat) or hydrogenated rapeseed triglycerides (RFT, 6.7% fat). Calves were offered milk replacer up to 920 g/d until 42 d of age, followed by a gradual weaning period of 7 d. Calves had ad libitum access to the starter diets, straw, and water. No differences were observed between CON, PFA, and RFT calves on body weight (BW) or average daily gain (ADG) until 49 d of age. From weaning (50 d) until 112 d, PFA calves had a greater BW and ADG than RFT and CON animals. Moreover, PFA calves had the highest intakes of starter, straw, calculated metabolizable energy, and crude protein after weaning. Overall, no differences were present in blood β-hydroxybutyrate and glucose concentrations between treatments; however, calves in the RFT treatment had a higher concentration of insulin-like growth factor-1. In experiment 2, 24 Holstein bull calves at 3 mo of age were assigned to 1 of 8 blocks based on arrival BW and age. Within each block, calves were randomly assigned to 1 of the 3 treatments previously described for experiment 1. Calves on the RFT treatment had the lowest total-tract apparent dry matter and fat digestibility, potentially explaining the differences in performance observed between PFA and RFT calves. Inclusion of the PFA pellet at 10% with a calf starter improved BW, solid feed, and energy intake after weaning. However, these benefits were conditioned by fat source and its digestibility.     

Effects of canola meal inclusion rate in starter mixtures for Holstein heifer calves on dry matter intake,average daily gain,ruminal fermentation,plasma metabolites,and total-tract digestibility

The objective of this study was to determine the effects of the canola meal (CM) inclusion rate in pelleted starter mixtures for Holstein heifer calves on dry matter intake, average daily gain, ruminal fermentation, plasma metabolites, and total-tract digestibility. Fifty Holstein heifer calves were blocked by birth date and body weight and, within block, randomly assigned to 1 of 5 pelleted starter treatments with 0, 15, 30, 45, or 60% of the crude protein supplied by CM instead of soybean meal (SBM). Pellets were formulated to be similar in crude protein (24.3%), starch (26.6%), and neutral detergent fiber (17.8%) and were provided to calves starting on d 8 of age, with starter intake measured daily. From 8.0 ± 0.0 (mean ± standard deviation) d of age through d 35.3 ± 2.4, calves were fed milk replacer at 15% of body weight, offered in 3 equal feedings at 0600, 1500, and 2100 h. After that, a gradual 21-d step-down weaning process was imposed, where no further milk replacer was provided starting on d 57.0 ± 0.0. Data for milk replacer and starter intake were calculated to determine weekly averages. On d 62.2 ± 0.8 of age, blood was collected every 4 h and analyzed for glucose, β-hydroxybutyrate, insulin, and urea concentrations. From d 66.2 ± 0.8 of age and extending for 3 d, fecal samples were collected every 12 h with a 3-h daily offset, to estimate fecal nutrient output and to determine apparent total-tract digestibility. Additionally, ruminal fluid (d 70.2 ± 0.8 of age) was sampled at 1300 h through an esophageal tube connected to a vacuum pump. The pH of ruminal fluid was measured, and ruminal fluid was analyzed to determine short-chain fatty acid and ammonia concentrations. Data were analyzed with fixed effect of treatment and random effect of block. Polynomial contrasts were calculated to assess linear, quadratic, and cubic effects with repeated measures statement for variables analyzed over time. Starter intake, average daily gain, body weight, and feed efficiency did not differ among treatments. Crude protein and ether extract digestibility were affected in a cubic manner, where CP was greatest for CM0, CM30, and CM45, and ether extract digestibility was least for CM15 and CM60. The molar proportion of acetate responded cubically, but the proportions of propionate and butyrate did not differ among treatments. Ruminal ammonia and plasma urea concentrations were not affected by CM inclusion rate. In conclusion, CM can replace up to 60% of the CP provided from SBM without affecting starter intake and growth of calves.     

Growth performance of calves fed microbially enhanced soy protein in pelleted starters

Our objective was to determine effects of feeding calves pelleted starters with microbially enhanced (fungi-treated) soy protein (MSP) in replacement of soybean meal (SBM) with different milk replacers (MR). Thirty-six Holstein calves (2 d old; 24 females, 12 males) in individual hutches were used in a 12-wk randomized complete block design study. Treatments were (1) MSP pellets with MR formulated for accelerated growth (28% crude protein, 18% fat; MSPA), (2) SBM pellets with MR formulated for accelerated growth (SBMA), and (3) MSP pellets with conventional MR (20% crude protein, 20% fat; MSPC). Pellets were similar except for 23% MSP or 23% SBM (dry matter basis). Pellets and water were fed ad libitum throughout the study. Feeding rates of MR on a dry matter basis were 0.37 kg twice daily during wk 1, 0.45 kg twice daily during wk 2 to 5, and 0.45 kg once daily during wk 6. Intakes were recorded daily. Body weights, frame size measurements, and jugular blood samples were collected 2 d every 2 wk at 3 h after the morning feeding. Fecal grab samples were collected 5 times per d for 3 d during wk 12 and then composited by calf for analysis of apparent total-tract digestibility of nutrients using acid detergent insoluble ash as an internal marker. Total and starter pellet dry matter intake were greatest for calves fed SBMA and least for MSPC. Calves had similar average daily gain among treatments, but there was a treatment by week interaction and during the last few weeks of the study calves on MSPC had less body weight compared with MSPA or SBMA. Gain-to-feed ratio was similar among treatments; however, there was a treatment by week interaction. Serum glucose was similar among treatments. Plasma urea nitrogen was greatest for calves fed MSPA and least for MSPC. Plasma concentrations of IGF-1 were greatest for calves fed SBMA. Plasma concentrations of triglycerides were greatest for calves fed MSPC. Plasma concentrations of β-hydroxybutyrate had a treatment by time interaction. Treatments had similar total-tract dry matter digestibility, but calves fed MSPC had greater crude protein digestibility than SBMA, with MSPA similar to both. Results demonstrated calves fed pelleted starters with MSP had maintained growth performance with less starter intake compared with SBM.     

Effects of feeding milk replacer at 2 rates with pelleted,low-starch or texturized,high-starch starters on calf performance and digestion

Milk replacer (MR) feeding programs have traditionally fed at less than ad libitum amounts to promote calf starter (CS) intake and allow early weaning. More recently, increased amounts of MR preweaning have been shown to increase preweaning ADG, although postweaning growth may be reduced. Several studies suggest that limited postweaning digestion of nutrients in CS may contribute to postweaning growth impairment. It is not clear whether CS formulation might also contribute to differences in postweaning nutrient digestion when calves are fed different MR programs. A 56-d feeding and digestion trial was conducted to compare growth and digestion in 2- to 3-d-old male Holstein calves (n = 48; initially 41.9 kg of body weight) fed a moderate (MRM) or high (MRH) MR program and either a pelleted CS containing 9.9% starch or a texturized CS containing 41.3% starch. Programs were 0.66 kg of dry matter (DM)/d of MR to d 46, then 0.33 kg/d to d 49 (MRM) and 0.85 kg of DM/d to d 5, then 1.07 kg/d to d 42, then 0.53 kg/d to d 49 (MRH). The MR contained 25% crude protein and 18.6% fat and was reconstituted to 13 (MRM) or 15% (MRH) solids. Calves were also assigned randomly to receive a pelleted CS (9.9% starch, 36.9% NDF) or a textured CS (41.3% starch, 13.3% NDF) and water for ad libitum intake for 56 d. During d 31 to 35 and 52 to 56, fecal samples were collected from 5 calves per treatment for estimates of digestibility. Selected nutrients and chromic oxide (d 31–35) or acid-insoluble ash (d 52–56) were analyzed in feed and feces to estimate digestibility. Data were analyzed as a completely randomized design. Repeated measures analysis was performed when data were measured by week. Calves fed MRH gained more body weight (but not hip width) and were more efficient to weaning compared with calves fed MRM, although fecal scores and days treated with medications were greater. We found no effect of CS on animal performance, although calves fed textured CS had higher fecal scores. Digestibilities of nutrients were affected by treatment and time of sampling (5 or 8 wk). At 5 wk, digestion of DM, organic matter, crude protein, and fat were lower and digestion of acid detergent fiber, neutral detergent fiber, and starch were higher in calves fed MRM and reflected greater CS intake. Also, digestion of DM, organic matter, acid detergent fiber, starch, crude protein, and fat were greater in calves fed textured CS at 5 wk. By 8 wk, when CS was the only source of nutrients, digestion of DM, organic matter, acid detergent fiber, and neutral detergent fiber were greater in calves fed MRM and digestion of DM and organic matter were greater, and acid detergent fiber and neutral detergent fiber digestion were lower in calves fed textured CS. Formulation of CS as well as amount of MR offered to young calves influenced animal performance and digestion in this study.