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.     

Growth characteristics of calves fed an intensified milk replacer regimen with additional lactoferrin

The objective of this study was to evaluate the effect of lactoferrin addition to milk replacer varying in crude protein (CP) on dry matter intake, growth, and days medicated. Thirty-four Holstein heifer calves were assigned to 4 treatments in a 2 × 2 factorial arrangement of treatments in a randomized complete block design. Treatments were as follows: 562 g daily of a nonmedicated conventional milk replacer (20% CP:20% fat) feeding regimen with or without 1 g of supplemental bovine lactoferrin (n = 9 for both treatments) or a nonmedicated intensified milk replacer feeding regimen (28% CP:20% fat) fed on a metabolizable energy basis (0.2 Mcal/kg BW^0.75) from d 2 to 9, and at 0.27 Mcal/kg BW^0.75 from d 10 to 42 with or without 1g supplemental bovine lactoferrin (n = 8 for both treatments). Calves were fed pelleted starter (25% CP) in 227.5-g increments beginning on d 2 and had free access to water. Calves remained on the study for 14 d postweaning. Dry matter intake was determined daily. Growth measurements were taken weekly. Blood samples were taken twice weekly for determination of blood urea N. On d 10 of life, calves were subjected to a xylose challenge. Calves on conventional treatments ate more starter preweaning, during weaning, and postweaning. Preweaning, intensively fed calves had higher dry matter intakes. Weights of intensified-fed calves were greater at weaning. Intensified milk replacer-fed calves had greater average daily gain preweaning and overall and higher gain:feed ratios preweaning, but conventionally fed calves had higher gain:feed ratios during weaning. Intensified milk replacer-fed calves had greater hip heights during weaning and postweaning and greater heart girths preweaning, weaning, and postweaning. Days medicated were greater preweaning and overall for intensified-fed calves. There were no differences among treatments for xylose absorption. Calves on conventional treatments had increased blood urea nitrogen concentrations preweaning. There were no effects of lactoferrin on any experimental variable. Intensified milk replacer-fed calves consumed less starter but had higher average daily gains overall and larger frames and greater BW than conventionally fed calves. An intensified milk replacer feeding regimen promotes faster growth during the preweaning period when compared with calves fed conventional treatments, but supplemental bovine lactoferrin was not beneficial under these experimental conditions.     

Impact of conventional or intensive milk replacer programs on Holstein heifer performance through six months of age and during first lactation

The objectives were to evaluate the impact of conventional or intensive milk replacer (MR) feeding programs on heifer calf performance through 6 mo of age, age at first calving, and first lactation performance. At 3 (±1 d) d of age, 133 Holstein heifer calves from 3 commercial dairy farms were randomly assigned, within calf source, to a conventional [20% crude protein (CP), 20% fat] or intensive MR (28% CP, 18% fat). Milk replacer treatments and percent solids were 1) conventional nonacidified (CNA), 13.9%; 2) conventional acidified (CA), 13.9%; 3) modified intensive high solids (IHS), 16.7%; 4) modified intensive low solids (ILS), 12.5%; and 5) intensive high solids, high feeding (IHSHF), 16.7%. Calves were individually housed and remained on trial for 56 d. At 2 mo of age, heifers were grouped in pens by treatment with 6 heifers per pen (4 pens per treatment). An 18.1% CP grower concentrate mix (dry matter basis) was fed to heifers that received a conventional MR and a 21.2% CP grower concentrate mix was fed to heifers that received the intensive MR preweaning. Heifers were offered 2.45 kg/d (dry matter basis) of their respective grower concentrate mix for 112 d plus free access to hay and water. At approximately 24 wk of age, heifers were transported to a second-stage grower before returning to their respective farms approximately 1 mo before calving. First-lactation performance was determined using Dairy Herd Improvement Association records. The IHSHF treatment resulted in increased calf body weight and hip height during the preweaning and early postweaning (PEP) period and the postweaning heifer grower (PHG) period as compared with the conventional (CNA and CA) or modified intensive MR treatments (IHS and ILS). Calves receiving the IHS treatment were heavier at d 56 of the PEP period compared with the conventional or ILS treatments; however, this growth advantage was not maintained in the PHG period. Feed cost per kilogram of gain during the PEP period was lowest for CNA and CA, intermediate for IHS and ILS, and highest for the IHSHF treatment. There was no effect of MR feeding program on first-lactation performance; however, heifers that received the IHSHF MR preweaning calved 27.5 d earlier than those fed a conventional MR.     

Effect of milk replacer program on digestion of nutrients in dairy calves

There are concerns with feeding young dairy calves amounts of milk solids approaching 0.9 kg of dry matter (DM) or more because of slumps in average daily gain (ADG) at weaning and low starter intakes. Additionally, programs feeding more than 0.6 kg of DM have not been thoroughly tested for success at different weaning ages. Four milk replacer (MR) programs were compared in trial 1. Program A was 0.44 kg of DM of a 21% crude protein (CP), 21% fat MR powder fed daily for 42 d. Program B was 0.66 kg of DM of a 27% CP, 17% fat MR powder fed daily for 42 d. Program C was 0.66 kg of DM of a 27% CP, 17% fat MR powder daily fed for 28 d. Program D was up to 1.09 kg of DM of a 29% CP, 21% fat MR daily fed for 49 d. Digestibility estimates were made and blood was sampled for serum constituents on d 53 to 56, and performance was measured for 84 d. Three programs feeding a 27% CP, 17% fat MR powder were compared in trial 2 over 56 d. Calves on program A were fed 0.66 kg of DM powder daily and weaned at 28 d. Calves on program B were fed 0.66 kg of DM powder daily and weaned at 42 d. Calves on program C were fed up to 1.09 kg of DM powder daily and weaned at 42 d. Digestibility estimates were made and blood was sampled for serum constituents d 21 to 24, d 36 to 39, and d 53 to 56. In trial 1, calves fed program A had the least overall ADG. Calves fed program D had the greatest ADG from 0 to 56 d, the least ADG from d 56 to 84, the least digestibility estimates, and the least concentrations of serum amylase. At 84 d, there were no differences in body weights of calves fed programs B, C, and D. In trial 2, calves fed program A had the greatest starter intake and greatest concentrations of serum amylase. Calves fed program C had the least estimates of digestibility from d 53 to 56 and the least serum concentrations of amylase. Calves fed up to 1.09 kg/d of 27 to 29% MR powders and weaned at 42 or 49 d had lower starter intakes, concentrations of serum amylase, and digestion of starter postweaning compared with calves fed conventional 21% CP, 21% fat MR powders fed at 0.44 kg/d. Calves fed 0.66 kg/d of a 27% CP, 17% fat MR powder and weaned at 28 or 42 d of age had no reductions in intake or digestion compared with calves fed conventional MR and gained as much total body weight from 0 to 84 d as calves stepped up to 1.09 kg of MR.     

Macronutrient profile in milk replacer or a whole milk powder modulates growth performance,feeding behavior,and blood metabolites in ad libitum-fed calves

Milk replacers (MR) for calves usually contain more lactose and less fat than bovine whole milk (WM). There are insufficient data to determine whether these MR formulations are optimal for calves fed at high planes of nutrition. Thus, the effect of 3 MR formulations and a WM powder were evaluated on growth, feeding behavior, and blood metabolites in 96 male Holstein calves fed ad libitum and with 45.5 ± 4.30 kg (mean ± standard deviation) BW at arrival. Calves were blocked based on arrival sequence, and randomly assigned within block to one of the 4 treatments (n = 24 calves/group): a high-fat MR (25.0% fat, dry matter basis; 22.5% protein, 38.6% lactose; 21.3 MJ/kg; HF), a high lactose MR (44.6% lactose, 22.5% protein, 18.0% fat; 19.7 MJ/kg; HL), a high protein MR (26.0% protein, 18.0% fat, 41.5% lactose; 20.0 MJ/kg; HP), and a WM powder (26.0% fat; 24.5% protein, 38.0% lactose; 21.6 MJ/kg; WP). In the first 2 wk after arrival, calves were individually housed and were fed 3.0 L of their respective liquid feed 3 times daily at 135 g/L. They were then moved to group housing and fed ad libitum until d 42 after arrival. Weaning was gradual and took place between d 43 and 70 after arrival; thereafter, calves were fed solids only. Concentrates, chopped straw, and water were available ad libitum throughout the study. Body weight was measured, and blood was collected at arrival and then weekly thereafter from wk 1 to 12. Weight gain and height were greater in HL than WP calves. In the preweaning phase, HL and HP-fed calves consumed more milk than WP, and HL-fed calves consumed more milk than HF calves. In wk 10, starter feed intakes were lower in HF calves than in the other groups. In the preweaning phase, ME intakes were the same for all treatments. This suggests that milk intakes were regulated by the energy density of the milk supplied. The percentage of calves requiring therapeutic interventions related to diarrhea was greater in WP-fed calves (29%) than HF and HL calves (4%), whereas HP (13%) did not differ with other groups. This was coupled with lower blood acid–base, blood gas, and blood sodium in WP than in MR-fed calves. Calves fed HF had greater serum nonesterified fatty acids compared with other groups, and greater serum amyloid A compared with WP and HL calves. Among the serum parameters, insulin-like growth factor-1 and lactate dehydrogenase correlated positively with ME intake and average daily gain. The high lactose and protein intakes in HL and HP calves led to greater insulin-like growth factor-1 concentrations than in WP-fed calves. Although growth differences were limited among MR groups, the metabolic profile largely differed and these differences require further investigation.     

Effects of spray-dried animal plasma in calf milk replacer on health and growth of dairy calves

Male Holstein calves (n = 120) purchased from local dairy farms were fed one of three calf milk replacers for 42 d. Experimental milk replacers were formulated to contain whey protein concentrate (WPC) as the primary protein source or WPC plus 5% spray-dried bovine plasma (SDBP) or spray-dried porcine plasma (SDPP). The SDPP was heated to remove heat-insoluble materials and provide products with similar IgG content. Calves were also fed commercial calf starter and water for ad libitum consumption. Intake, change in body weight (BW), feed efficiency, morbidity and mortality were determined. Mortality was 10, 3, and 2 in calves fed WPC, SDBP, and SDPP treatments, respectively. Morbidity, measured as the number of days that calves had diarrhea was reduced by 30% when SDBP or SDPP were fed. Calves had diarrhea for 6.9, 3.9, and 4.7 d during the 42-d study when fed commercial calf milk replacer containing WPC, SDBP, and SDPP, respectively. Fecal scores tended to be reduced and feed efficiency tended to be improved when SDBP or SDPP were fed. Mean intakes of total dry matter during the 42-d study were greater when calves were fed SDBP or SDPP and were 661, 710, and 684 g/d for calves fed WPC, SDBP, and SDPP, respectively. Mean BW gains from d0 to 42 were 231,261, and 218 g/d, respectively. Calves fed SDPP tended to have lower BW gain during the first 28 d of the study. However, difference in daily BW gain from d 1 to 28 was only 39 g/d. Inclusion of SDBP or SDPP in milk replacer reduced morbidity and mortality of milk-fed dairy calves.     

Preweaning nutrient supply alters serum metabolomics profiles related to protein and energy metabolism and hepatic function in Holstein heifer calves

Lifting the preweaning milk restriction in dairy calves has been causally associated with beneficial effects on growth and future lactation performance. However, the biological mechanisms linking early-life nutrient supply and future performance remain insufficiently understood. Thus, the objective of this study was to characterize growth and the metabolic profiles of calves fed a restricted (RES) and an elevated (ELE) milk supply preweaning. A total of 86 female Holstein Friesian calves were blocked in pairs by maternal parity and received identical colostrum supply within block. Treatments randomized within block consisted of a milk replacer (MR; 24% crude protein, 18% crude fat, and 45% lactose) supplied at either 5.41 Mcal of ME in 8 L of MR/d (ELE) or 2.71 Mcal of ME in 4 L of MR/d (RES) from d 2 after birth until they were stepped down by 50% during wk 7 and fully weaned at wk 8. All calves had ad libitum access to pelleted calf starter (17.3% crude protein, 24.4% neutral detergent fiber, 2.0% crude fat, and 18.2% starch), chopped wheat straw, and water. At 2 and 49 d of age, blood samples were taken for metabolomics analysis. The ELE group by design consumed more milk replacer, resulting in a lower starter intake and a greater body weight and average daily gain. The ELE calves consumed 20.7% more ME and 9.7% more crude protein. However, efficiency of growth was not different between groups. Metabolomic profiling using 908 identified metabolites served to characterize treatment-dependent biochemical differences. Principal component analysis revealed clearly distinct metabolic profiles at 49 d of age in response to preweaning milk supply. Changes in energy (fatty acid metabolism and tricarboxylic acid metabolites), protein (free AA, dipeptides, and urea cycle), and liver metabolism (bile acid and heme metabolism) were the main effects associated with the dietary differences. The ELE group consumed proportionately more glucogenic nutrients via milk replacer, whereas the RES group consumed proportionately more ketogenic nutrients from the digestion of the calf starter, comprising a larger portion of total intake. Associated with the higher growth rate of the ELE group, hepatic changes were expressed as differences in bile acid and heme metabolism. Furthermore, energy metabolism differences were noted in fatty acid and AA metabolism and the urea cycle. The metabolic profile differences between the ELE and RES groups reflect the broad differences in nutrient intake and diet composition and might point to which metabolic processes are responsible for greater dairy performance for cows fed a greater milk supply preweaning.     

Effects of feeding different amounts of milk replacer on growth performance and nutrient digestibility in Holstein calves to 2 months of age using different weaning strategies

Growth and the digestibility of nutrients can be greatly affected by diet preweaning and the rate at which calves are weaned. A 2 × 2 factorial design [moderate (MOD) or high (HI) milk replacer (MR) feeding rates and abrupt (AB) or gradual (GR) weaning] was used to compare these effects. Calves (n = 50) were randomly assigned to 1 of 4 treatments: MOD-AB, MOD-GR, HI-AB, and HI-GR. Calves assigned to MOD-AB were fed 0.66 kg of MR for the first 42 d and then 0.33 kg for the last 7 d; those assigned to MOD-GR were fed 0.66 kg of MR for 28 d, 0.33 kg for 14 d, and 0.17 kg for the last 7 d; those assigned to HI-AB were fed 0.66 kg of MR for 7 d, 0.82 kg for 7 d, 1.1 kg for 28 d, and 0.66 kg for the last 7 d; and those assigned to HI-GR were fed 0.66 kg of MR for 7 d, 0.82 kg for 7 d, 1.1 kg for 14 d, 0.66 kg for 14 d, and 0.33 kg for the last 7 d. All calves received the same MR [25% crude protein (CP), 17% fat; dry matter (DM) basis] and were given ad libitum access to water and a textured starter (42% starch and 20% CP). On d 26 to 30 and d 45 to 49, a fecal sample was taken from 5 calves in each treatment via the rectum to estimate apparent digestibility coefficients (dC). Apparent dC of DM, organic matter, and fat were greater for HI versus MOD calves. Apparent dC of neutral detergent fiber, acid detergent fiber, and sugar were greater for MOD versus HI calves. Apparent dC of DM was greater for AB versus GR calves [90.9, 89.0 ± 0.5384 (standard error)], and the apparent dC of acid detergent fiber was greater for GR versus AB calves (39.5, 32.3 ± 1.67). Feed efficiency was greater for HI versus MOD and AB versus GR. There were no significant differences between CP or starch dC based on treatment, and no interactions were observed. Starter consumption was greater for MOD calves compared with HI calves, and GR calves consumed more than AB calves. These results suggest that providing calves high amounts of MR preweaning enhanced readily available nutrient dC, but providing moderate amounts of MR resulted in increased fibrous fraction dC. Accordingly, the AB weaning strategy had higher dC for DM and organic matter, but there was a depression in fiber dC.     

Effect of feeding frequency and route of administration on abomasal luminal pH in dairy calves fed milk replacer

The aim of this study was to determine the effect of feeding frequency and route of administration on abomasal luminal pH in suckling calves. Six male dairy calves with cannulae in the abomasal body were administered the following six treatments in a randomized crossover design: 24 h fasting, suckling of a high-quality milk replacer (all-milk protein; 12% of body weight [BW]/d) at 12-h (2x), 8-h (3x), 6-h (4x), and 3-h (8x) intervals, and ruminal intubation of milk replacer (12% of body weight/day) at a 12-h (2x) interval. Abomasal luminal pH was measured every second for 24 h with miniature glass pH electrodes. Least squares mean 24-h fasting abomasal luminal pH was 1.73, whereas mean 24-h pH after suckling and intubation of milk replacer every 12 h were higher at 3.44 and 3.17, respectively. Increasing the frequency of milk replacer suckling to 3x, 4x, and 8x increased mean 24-h abomasal luminal pH; however, there was no difference in mean 24-h pH between 3x (3.69), 4x (3.64), and 8x (3.67) suckling. The percentage of the 24-h recording period that abomasal luminal pH was > 3.0 was 0, 49, 53, 61, 61, and 71% for fasting, 2x intubation of milk replacer, and 2x, 3x, 4x, and 8x suckling of milk replacer, respectively. Increasing the frequency of milk replacer suckling may be efficacious in the prophylaxis of abomasal ulceration in milk-fed calves.     

Optimal concentrations of lysine, methionine, and threonine in milk replacers for calves less than five weeks of age

The AA requirements of herd-replacement calves less than 5 wk old and fed milk replacers are not clearly defined and have been estimated in a limited number of studies using milk-fed calves ranging from 5 to 20 wk of age. The objective of these 4 studies was to investigate the effect of supplementing milk replacers containing 24 to 28% crude protein (CP; from milk sources) and 17% fat with Lys, Met, and Thr to estimate the optimum requirements for calves less than 5 wk of age. Holstein bull calves (initially 3 and 4 d old, 43 ± 1 kg of body weight, BW) were fed an 18% CP (as-fed) starter ad libitum and weaned at 31 to 32 d of age (28-d studies). Calves were housed in an unheated, curtain-sided nursery. In study 1, 6 milk replacer treatments were fed based on the combination of 3 CP concentrations (24, 26, and 28% CP) each with or without added Lys and Met. In studies 2 and 3, 26% CP and 2.34% Lys milk replacer treatments were fed to test the concentration of Met (0.64, 0.68, and 0.72% Met in study 2 and 0.64, 0.72, and 0.80% Met in study 3). In study 4, 26% CP, 2.34% Lys, and 0.72% Met milk replacer treatments were fed to test the concentration of Thr (1.06, 1.43, and 1.80%). There was a 17% improvement in average daily gain (ADG) in study 1 from adding Lys and Met that was maximized with 2.34% Lys. The ADG response to added Met in studies 2 (linear) and 3 (quadratic) were 13 and 7%, respectively, with a plateau at 0.72% Met. There was no ADG or efficiency response to added Thr in study 4. Formulating 17% fat, whey-based milk replacers fed at 0.68 kg/d to 26% CP, 2.34% Lys, and 0.72% Met appeared optimum based on responses of body weight gain, feed efficiency, and serum concentrations of urea nitrogen, while feeding calves more CP and essential AA did not improved ADG and efficiency. Requirements for calves less than 5 wk old, averaging 48 kg of BW, consuming 204 g of CP/d, and gaining 0.46 kg of BW/d, appeared to be met with 17 g of Lys, 0.31 Met:Lys ratio, 0.54 Met+Cys:Lys ratio, and a Thr:Lys ratio less than 0.60.     

Effect of milk replacer feeding rate and frequency of preweaning dairy calves in the southeastern United States: Glucose metabolism

The objective of this experiment was to examine the effect of milk replacer (MR) feeding rate (FR) and frequency (FF) on glucose metabolism before and after weaning during summer and winter in the subtropical climate of the southeastern United States. Holstein calves (n = 48/season) were enrolled at 8 d of age (DOA) in the summer (June to August, body weight = 40.6 ± 0.7 kg) and winter (November to January, body weight = 41.9 ± 0.8 kg). In each season, calves were randomly assigned to 1 of 4 treatments in a 2 × 2 factorial arrangement including 2 FR [0.65 (low) or 0.76 kg of solids/d (high) of a 26% CP and 17% fat MR] and 2 FF [2× (0700 and 1600 h) or 3× (0700, 1600, and 2200 h)]. Calves were managed similarly and housed in polyethylene hutches bedded with sand. Milk replacer (12.5%) was fed based on treatments until 42 DOA when FR was reduced by half and offered 1×/d (0700 h) for 7 d. Plasma was collected weekly at 1400 h for analyses of glucose and insulin concentrations in all calves. Pre- and postprandial glucose and insulin concentrations of a subset of calves (n = 10/treatment per season) were measured on 20 DOA. A subset of calves (n = 8/treatment per season) was subjected to an intravenous glucose tolerance test (GTT) on 27 and 57 DOA and insulin challenge on 28 and 58 DOA at 1030 h. Average ambient temperature was 26.1 ± 2.2°C in summer and 12.9 ± 5.4°C in winter. During the preweaning period in both seasons, feeding high increased plasma glucose concentrations compared with low, and increasing FF reduced basal insulin concentrations. Compared with 2×, feeding 3× did not affect postprandial glucose but lowered insulin in the summer, whereas in the winter, increased glucose from 30 to 180 min but lowered insulin from 240 to 420 min after MR feeding. Following GTT before weaning in both seasons, 3× reduced insulin increment and area under the curve compared with 2× without affecting glucose disposal. After weaning, treatment did not affect glucose disposal or insulin responses after GTT during winter, but calves fed 3× had faster glucose disposal and stronger insulin responses than 2× during summer. In both summer and winter, preweaned calves fed 3× had greater decrement and area under the curve of plasma glucose after insulin challenge, suggesting enhanced peripheral tissue insulin response compared with 2×. This effect persisted after weaning only during summer. Increasing FR had no effect on metabolic responses in both seasons. In conclusion, increasing MR FF from 2 to 3 times per day reduced insulin secretion but enhanced insulin response on peripheral tissues of preweaned calves regardless of season.     

Optimizing nutrient ratios in milk replacers for calves less than five weeks of age

In trials 1A and 1B, the objective was to determine whether crude protein (CP) concentration could be lowered from 27% CP if Lys and Met were held constant. Forty-five calves per trial were fed milk replacer (MR) powders that contained 23, 25, or 27% CP (dry matter basis) from whey protein. Each MR powder contained 17% fat, 2.44% Lys, 0.75% Met, and 1.56% Thr by adding l-Lys, dl-Met, and l-Thr, and were fed at 0.681 kg/d. In trial 2, the objective was to estimate an optimal CP-to-energy ratio for 2 different amounts of MR fed. Ninety-six calves were fed 1 of 8 MR powders (dry matter basis): 1) 23% CP fed at 0.545 kg/d, 2) 25% CP fed at 0.545 kg/d, 3) 27% CP fed at 0.545 kg/d, 4) 29% CP fed at 0.545 kg/d, 5) 23% CP fed at 0.654 kg/d, 6) 25% CP fed at 0.654 kg/d, 7) 27% CP fed at 0.654 kg/d, and 8) 29% CP fed at 0.654 kg/d. In each MR, l-Lys and dl-Met were added to achieve a Lys:CP ratio of 0.09 and a Met:Lys ratio of 0.31. Holstein calves initially 2 to 3 d old and 43 ± 1 kg of body weight (BW) from 1 farm were fed MR until weaning at 28 d and were monitored for a total of 56 d. Calves were fed an 18% CP starter and water free choice from d 1 and were housed in individual pens bedded with straw in a naturally ventilated nursery with no added heat. Trials 1A and 1B were analyzed individually as completely randomized designs with repeated measures in a mixed model. Trial 2 was analyzed as a completely randomized block design with a factorial arrangement of 2 rates and 4 CP concentrations with repeated measures in a mixed model. In trials 1A and 1B, preweaning average daily gain (ADG) and feed efficiency declined as CP declined. Postweaning performance did not differ among treatments. In trial 2, preweaning ADG was greater and starter intake was lower at the high MR compared with the low MR feeding rate. Pre- and postweaning and overall ADG increased quadratically as CP increased. Preweaning MR rate interacted with CP; thus, at the low MR rate, providing 3.26 Mcal of metabolizable energy (ME)/d (0.0656 Mcal/kg of BW daily), 51.5 g of CP/Mcal of ME was the optimal ratio in the MR (25% CP, 17% fat, 2.26% Lys, and 0.68% Met) to maximize ADG. At the high ME intake, providing 3.71 Mcal/d (0.0743 Mcal/kg of BW daily), 55.0 g of CP/Mcal of ME was the optimal ratio in the MR (27% CP, 17% fat, 2.44% Lys, 0.75% Met) to maximize ADG.     

Effects of vegetable fats versus lard in milk replacers on feed intake, digestibility, and growth in Finnish Ayrshire bull calves

The aim was to study whether vegetable fat mixtures could be used instead of lard [15.2% in dry matter (DM)] in milk replacers without impairing the performance of Finnish Ayrshire bull calves (n = 58). The growth performance of the calves was measured before and after weaning from 14 d to 6 mo of age. The following 3 fat sources in a milk replacer were studied: 1) a mixture of palm, coconut, and rapeseed oil, 2) palm and coconut oil, and 3) lard. The calves were bucket-fed 2 L of milk replacer 3 times per day. The milk replacer contained 116 g of DM/L, resulting in an average DM intake of 4.8 g of DM/kg of body weight^0.75 (BW^0.75) during the 8-wk trial, after which the calves were weaned. All the calves had free access to water, commercial starter, and grass silage before weaning. The weaned calves had free access to water and grass silage and were given 3 kg/d (air-dry basis) of a commercial concentrate mixture. The concentrate was replaced by barley when the bulls were 4.5 mo old. There were no significant differences between the diets in feed intake and apparent diet digestibility. The health and BW of the calves were similar during the study. The feed conversion rate (kg of DM intake/kg of gain) before weaning was significantly greater for the lard diet compared with the 2 vegetable fat mixtures. After weaning, the feed conversion rate was slightly lower for the diet that included the palm, coconut, and rapeseed oil mixture than for the diet that included palm and coconut oil mixture. The study showed that the 2 mixtures consisting solely of vegetable oils were effective dietary components, thus providing 2 alternative fat mixtures of milk replacers, for use instead of lard in formulating commercial calf milk replacers.     

Effects of feeding milk replacer once versus twice daily on glucose metabolism in Holstein and Jersey calves

Eighteen Holstein (experiment 1) and 15 Jersey (experiment 2) heifer calves were fed milk replacer once or twice daily to determine effects of feeding frequency on weight gain, starter intake, and glucose metabolism. Body weights were measured weekly from birth to 8 wk. Blood samples were collected at wk 1 through 6 from all calves before and at 30, 60, 90, 120 and 180 min after the morning feeding. Plasma was analyzed for glucose, insulin, glucagon, and nonesterified fatty acids (NEFA). Urine was collected 90 min postfeeding to measure glucose concentration. Treatment did not affect mean starter intake or body weight. In experiments 1 and 2 mean plasma glucagon, glucose, NEFA, and insulin and urinary glucose concentrations were not affected by treatment. There was an interaction of sampling time and treatment for plasma insulin concentrations but not for glucose concentrations in both experiments. Following feeding, calves fed milk replacer once daily had higher insulin concentrations than those fed twice daily. There was an interaction of sampling time and treatment for plasma NEFA concentrations in Jersey calves only. Jersey calves fed milk replacer once daily had higher plasma NEFA concentrations before the morning milk replacer feeding. At wk 3 and 6, frequently sampled intravenous glucose tolerance tests were performed to assess glucose effectiveness, insulin sensitivity, and acute insulin response. In experiments 1 and 2 glucose effectiveness and insulin sensitivity were similar regardless of milk replacer feeding frequency. In Holstein and Jersey calves fed milk replacer twice daily, acute insulin response was greater than in calves fed once daily. However, insulin sensitivity decreased with age, while acute insulin response increased with age. These data suggest that feeding calves milk replacer once daily did not deleteriously affect performance or glucose metabolism regardless of breed.     

Colostrum replacer feeding regimen,addition of sodium bicarbonate,and milk replacer: The combined effects on absorptive efficiency of immunoglobulin G in neonatal calves

Eighty Holstein and Holstein cross dairy calves were blocked by birth date and randomly assigned to 1 of 8 treatments within each block to examine the effect of a colostrum replacer (CR) feeding regimen, supplementation of CR with sodium bicarbonate (NaHCO₃), and provision of a milk replacer (MR) feeding on IgG absorption. Calves were offered a CR containing 184.5 g/L of IgG in either 1 feeding at 0 h (within 30 min of birth), with or without 30 g of NaHCO₃, with or without a feeding of MR at 6 h of age, or 2 feedings of CR (123 g of IgG at 0 h with or without 20 g of NaHCO₃ and 61.5 g of IgG at 6 h with or without 10 g of NaHCO₃), with or without a MR feeding at 12 h. Therefore, treatments were (1) 1 feeding of CR; (2) 2 feedings of CR; (3) 1 feeding of CR + 30 g of NaHCO₃; (4) 2 feedings of CR + 30 g of NaHCO₃; (5) 1 feeding of CR + MR feeding; (6) 2 feedings of CR + MR feeding; (7) 1 feeding of CR + 30 g NaHCO₃ + MR feeding; and (8) 2 feedings of CR + 30 g NaHCO₃ + MR feeding. Blood samples were obtained at 0, 6, 12, 18, and 24 h after birth and were analyzed for IgG via radial immunoassay. Results indicated that CR feeding schedule, MR feeding, and the interactions CR × Na, CR × MR, and CR × Na × MR were similar for 24-h serum IgG, apparent efficiency of absorption, or area under the curve. Serum IgG at 24 h, apparent efficiency of absorption, and area under the curve were decreased with addition of NaHCO₃ compared with calves not supplemented with NaHCO₃. These data indicate that supplementation of CR with NaHCO₃ is not beneficial to IgG absorption and feeding MR within 6 h of CR feeding does not affect IgG absorption.     

Effects of spray-dried animal plasma in milk replacers or additives containing serum and oligosaccharides on growth and health of calves

The effects of spray-dried animal plasma in milk replacer without or with the addition of additives containing fructooligosaccharides and spray-dried serum on health, growth, and intake of Holstein calves was measured in two 56-d experiments. In experiment 1, 120 calves were fed milk replacer containing 0 or 20% of crude protein as spray-dried bovine plasma for 42 d and 30 to 60 g/d of additives containing whey protein concentrate or bovine serum for the first 15 d. Commercial calf starter was available from d 29, and water was available at all times. In experiment 2, 120 calves were fed milk replacer containing 0 or 16% of crude protein as spray-dried bovine plasma with 0 or 30 to 60 g/d of additive containing bovine serum for the first 15 d. Additive containing bovine serum also contained fructooligosaccharides, whey, and vitamin/mineral premix. In experiment 1, calves fed additive containing bovine serum tended to have fewer days with diarrhea, lower use of electrolytes, and improved BW gain from d 29 to 56. The addition of spray-dried bovine plasma to milk replacer did not influence any parameter measured. In experiment 2, calves fed additive containing bovine serum or milk replacer containing spray-dried bovine plasma had lower mortality (4.4 vs. 20%) and tended to have improved fecal scores and fewer days with scours. Antibiotic use was lower when calves were fed the additive. Indices of enteric health (incidence of scours and treatment with antibiotics and electrolytes) were improved when plasma was added to milk replacer throughout the milk feeding period or as an additive during the first 15 d of the milk feeding period, when calves were most susceptible to enteric pathogens. The addition of spray-dried animal plasma to milk replacer or the addition of additive containing spray-dried bovine serum and oligosaccharides may be a useful adjunct to animal management during periods of stress.     

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 milk replacer feeding rate and frequency of preweaning dairy calves in the southeastern United States: Performance,abomasal emptying,and nutrient digestibility

To evaluate the effects of milk replacer (MR) feeding rate (FR) and frequency (FF) on performance, abomasal emptying, and nutrient digestibility in the southeastern United States, Holstein calves (n = 48/season) were enrolled at 8 d of age (DOA) during summer [June to August, body weight (BW; mean ± SD) = 40.71 ± 4.35 kg] and winter (November to January, BW = 42.03 ± 3.83 kg). Within season, calves were randomly assigned to 1 of 4 treatments in a 2 × 2 factorial arrangement including 2 FR [0.65 (low) or 0.76 kg of solid per day (high) of a 26% crude protein and 17% fat MR], and 2 FF [2× (0700 and 1600 h) or 3× (0700, 1600, and 2200 h) daily]. Calves were housed in polyethylene hutches and managed similarly throughout the trial. Milk replacer (12.5% solids) was fed to calves based on their respective treatments until 42 DOA, when MR allowance was reduced by 50% and offered once a day (0700 h) for the following 7 d until weaning. Calves remained on trial until 63 DOA. Calf starter and water were offered ad libitum. Ambient temperature and relative humidity inside and outside hutches were measured hourly. Starter and MR intakes were recorded daily. Respiration rate and rectal temperature were recorded 3 times a week. Structural growth and BW were measured weekly. Acetaminophen (50 mg/kg of BW) mixed with MR was fed to a subset of calves (0700 h, n = 10/treatment per season) on 20 DOA. Plasma was collected at 15, 30, 60, 90, 120, 150, 180, 210, 240, 270, 300, 330, 360, 420, and 480 min after feeding, to analyze acetaminophen. The acetaminophen concentration-time curve was modeled to the first derivative of Siegel's modified power exponential equation, and the time for plasma acetaminophen to reach maximum (Tmax) was calculated to evaluate abomasal emptying rate. During the pre- (14.9–17.9 DOA) and postweaning (51.0–54.0 DOA) periods, a subset (n = 8/treatment per season) of calves was used to determine the apparent digestibility of nutrients, using chromic oxide as the external marker. Feeding 3× reduced preweaning respiration rate during summer and reduced rectal temperature during winter. Increasing FR improved BW gain and structural growth. Feeding more times per day tended to improve growth during winter but not summer. We found no effect of treatment on nutrient digestibility. Increasing FR had no effect on Tmax during winter but tended to delay Tmax of plasma acetaminophen during summer. Regardless of season, increasing FF lowered Tmax of plasma acetaminophen. In conclusion, increasing FF accelerated abomasal emptying and might reduce heat load of preweaning dairy calves but improved growth only during winter. Increased MR allowance improved growth in both seasons but delayed abomasal emptying only under heat stress conditions.     

The effect of increasing the nutrient and amino acid concentration of milk diets on dairy heifer individual feed intake,growth, development,and lactation performance

Increasing early (<3 mo) nutrient feeding levels and growth rate of dairy calves has been found to increase their milk production potential. The objective of this study was to compare the effect of offering milk diets with or without added carbohydrates and amino acids on calf growth, weaning age, and subsequent growth and milk yield of dairy heifers in their first lactation. Friesian calves born at Massey University (n = 57) were selected at random, weighed, and allocated to receive 1 of 3 diets. All calves were fed colostrum from 1 to 3 d of age, followed by 4 L of whole milk (WM) per head per day and probiotics between 3 and 18 d of age. At 18 d of age, calves were weighed to ensure mean body weight (BW); then, at 19 d of age, calves changed diets to 1 of 3 treatments, which reached full treatment rate at 21 d of age. The diets were 4 L/head per day of WM (M); 4 L/head per day of WM plus 200 g of plant carbohydrates (MP); and 4 L/head per day of WM plus 200 g of plant carbohydrates with amino acids (MPA). Calves were weaned upon reaching a BW of 90 kg. During this period, BW, body condition, and hip height and width were measured. The heifers were commingled and grazed on ryegrass and white clover pastures until calving at 23 mo of age, when BW, body condition, and hip height and width were measured again. Milk yield and composition were measured throughout first lactation. At weaning, calves fed MPA had greater mean BW gain, a lower number of days to target BW, and a greater mean hip width gain compared with calves in the M group, although mean gain in hip height did not differ among treatments. Total calf starter intake during the milk period was lower for MPA-fed calves compared with those offered M, mainly due to a shorter milk feeding period required to attain the 90-kg weaning weight, whereas mean daily starter intake and straw intake did not differ. No difference was observed in the calving rate or calving age of heifers in any of the dietary feeding groups. First lactation fat-corrected milk yield, milk fat percentage, and total milk fat and protein yields were greater for animals reared on MP and MPA compared with M. Body weight, hip height and width at parturition, milk protein percentage, somatic cell count, or days in milk did not differ among treatments. Increasing nutrient intake, during the milk feeding period, improved the BW gain of calves and milk production of dairy heifers during first lactation.     

Effects of colostrum and milk replacer feeding rates on intake,growth, and digestibility in calves

Newborn Holstein male calves (n = 50) born on a single dairy farm were assigned randomly at birth to receive 3 feedings of 1.8 L of pooled maternal colostrum (MC) at 1, 6, and 12 h of age or 1 feeding of 500 g of a colostrum replacer reconstituted to 1.8 L at 1 h of age, followed by 2 feedings of 227 g of a commercial milk replacer (MR) reconstituted to 1.8 L at 6 and 12 h of age (CR). All feedings were administered by esophageal feeder. At 2 to 3 d of age, calves were transported to the experimental facility and assigned within colostrum group to receive 0.66 kg/d dry matter (DM) of MR to 39 d, and then 0.33 kg/d to 42 d (MRM) or 0.77 kg/d of MR DM to d 13, 1.03 kg/d for 22 d, and 0.51 kg/d for 7 d (MRH). The MR contained 25.8% crude protein and 17.6% crude fat (DM basis) and was based on whey proteins and lard as the primary fat source. Calf starter (21.7% crude protein, 15.7% neutral detergent fiber, 37.4% starch, DM basis) and water were available for ad libitum consumption throughout the 56-d study. Serum IgG and total protein were measured at 2 to 3 d of age. Intakes of MR and calf starter were monitored daily. Calf health and fecal scores were also monitored daily. Body weight was measured weekly, and hip width and body condition score were monitored every 2 wk. Digestion of DM, organic matter, crude protein, and ether extract were determined at 1 and 3 wk from 5 calves randomly selected within treatment and using chromic oxide as a digestibility marker added to the MR. Calves fed CR had lower serum IgG and total protein than calves fed MC. Also, calves fed CR grew more slowly, consumed less calf starter, and were less efficient to 56 d than calves fed MC. The number of days calves were treated with veterinary medications was higher when calves were fed CR. Calves fed MC-MRH gained more BW than other calves from 3 to 8 wk of age. Calves fed CR-MRH consumed less calf starter than other calves during wk 7 and 8. Digestion of nutrients at 1 and 3 wk of the study was unaffected by type of colostrum or level of MR fed and did not change from 1 to 3 wk. Over the first 2 mo of life, the calves fed MRH consumed less calf starter than calves fed MRM, but average daily gain or hip width change did not differ. One feeding of CR followed by 2 feedings of MR in the first 24 h likely reduced absorption of IgG from CR and contributed to differences in health and growth. Differences in animal performance observed in this study were unrelated to MR digestibility.