Supplemental fat for dairy calves during mild cold stress

Eighty-one Holstein and Holstein-cross dairy calves fed calf milk replacer (CMR) were used to determine response to increasing amounts of supplemental fat during mild cold stress. Calves (n = 27) were randomly assigned to 1 of 3 treatments: (1) low fat [LF; 28% crude protein:15% fat milk replacer (28:15 MR)]; (2) medium fat [MF; 28:15 MR + 113 g/d of commercial fat supplement (FS)]; (3) high fat (HF; 28:15 MR + 227 g/d of FS). The MF and HF calves received FS from d 2 to 21, and all calves were fed LF from d 22 to 49. The CMR was fed at 1.4% of birth body weight (BBW) from d 1 to 10, at 1.8% of BBW from d 11 to 42, and at 0.9% of BBW from d 43 to 49. Calves were weaned on d 49 and remained in hutches until d 56. The CMR was reconstituted to 13% solids. Calves were fed a commercial starter grain (19.2% crude protein on a dry matter basis) ad libitum and offered warm water after CMR feeding. Calves were fed CMR twice daily at 0630 and 1730 h in hutches bedded with straw. Starter intake, CMR intake, and ambient temperature were measured daily, and body weight (BW), hip height, and body length were measured weekly. Data were analyzed using PROC MIXED in SAS (SAS Institute Inc., Cary, NC) as a randomized design with linear and quadratic contrasts. Calf BBW averaged 42.0 ± 1.0 kg, total serum protein averaged 5.8 ± 0.1 mg/dL, and birth ambient temperature averaged 5.0 ± 1.1°C. Feeding FS increased metabolizable energy intake (ME_I) over maintenance but decreased efficiency of conversion of BW gain:ME_I. Starter intake by LF calves was greatest until the beginning of weaning, after which starter intake was similar among treatments. Because of higher starter intake, total ME_I was similar among treatments. Feed efficiency through d 49 was greater for calves fed MF and HF. Average daily gain during fat supplementation was greater for MF and HF than for LF. Lack of increase in BW gain and feed efficiency between MF and HF treatments indicated that HF did not result in advantages over MF. Supplementing fat to preweaned calves fed CMR increased BW gain and decreased starter intake through d 21 which had carryover effects on starter intake on d 49 and reduced hip height and tended to reduced withers height and body length by d 56. The addition of supplemental fat to LF, during mild cold stress, may result in a suboptimal ratio of crude protein to metabolizable energy in the CMR.     

Performance and health responses of dairy calves offered different milk replacer allowances

Eighty female Holstein calves (12 ± 4.1 d of age and 42 ± 4.3 kg of BW) were collected from different herds, brought to the study site, and blocked by age and assigned to either a 6 L/d maximum daily milk replacer (MR) allowance (LMR) or a maximum MR allowance of 8 L/d (HMR). Calves were kept in individual hutches until 52 d of age and then moved into pens, forming groups of 10. All calves had ad libitum access to a mash starter feed. Calves in both treatments received the MR distributed in 3 separate allotments between 1 wk after the beginning of the study and 52 d of age. Then, all calves were moved to group pens and preweaned by offering 2 L/calf of the same MR twice daily in a trough until the age of 59 d, when MR offer was further reduced to a single dose of 2 L until the age of 73 d, when all calves were completely weaned. Individual starter feed and MR consumption was recorded on a daily basis until 52 d of age, and on a group basis until weaning time. Body weight was measured at the beginning of the study and at 52 (preweaning), 73 (weaning), and 110, 160, and 228 d of age. Solid feed consumption (mean ± SE) was greater in LMR (821 ± 42.1 g/d) than in HMR calves (462 ± 42.1 g/d) between 42 d of age and 52 d (preweaning). As expected, as age increased, solid feed consumption increased, and LMR showed a more marked increase than HMR calves. Despite the greater solid feed intake of LMR calves, HMR grew faster than LMR calves until preweaning time, but from preweaning to weaning, LMR calves grew more than HMR calves (977 vs. 857 ± 30.7 g/d, respectively; mean ± SE). No differences in feed efficiency were observed. While calves were individually housed, no differences were observed in the incidence of bovine respiratory disease or diarrhea between treatment groups. We concluded that, under the milk regimen, age range of calves, and weaning method used in the current study, before preweaning, HMR calves grow more than LMR calves, but between preweaning and weaning, LMR grow more than HMR calves, overcoming the difference in BW at preweaning. As a result, with the weaning scheme followed herein, providing more milk does not ensure greater performance; no differences are obtained in BW at weaning and at 228 d of life. Also, based on solid feed consumption patterns seen in this study, we determined that the optimum age to reduce MR allowances and foster solid feed intake is around 45 d of age.     

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.     

Optimizing weaning strategies of dairy replacement calves

Two experiments were conducted to evaluate whether performance could be improved and incidence of respiratory problems decreased either by allocating 6 additional days of individual housing after weaning or by moving calves in groups before weaning at 2 different ages. The first experiment involved 320 female calves that received 2 L of milk replacer (MR) twice daily until 49 d of age, and then 2 L of MR once daily until weaning at 56 d of age. Half of the calves were allowed to remain individually housed for an additional 6 d after weaning, and the other half were moved immediately after weaning to a different pen holding 8 calves. The second experiment involved 240 female calves that received 2 L of MR twice daily until 49 d of age, and then 2 L of MR once daily. Half of the calves were moved at 49 d of age to superhutches holding 8 calves with an elevated trough that was used to continue delivering MR; the other half remained individually housed until the age of 56 d and were then moved to the superhutches, where they also continued to receive MR. Growth and incidence of respiratory problems were recorded in both experiments, and feed intake was recorded in experiment 2. Calves moved to groups immediately after weaning reached the target BW 6 d earlier and experienced a lesser incidence of respiratory afflictions than those grouped 6 d after weaning. From experiment 2, calves grouped at 49 d of age had a greater average daily gain and BW at 56 d of age as a result of a greater total solid feed consumption compared with those grouped at 56 d of age. Calves grouped at 56 d, however, had a greater average daily gain between 56 and 64 d of age (the week following grouping for the calves in the 56-d treatment) than those grouped at 49 d of age. Overall, the proportion of animals affected by a respiratory problem between 49 and 112 d of age did not differ between treatments. However, calves grouped at 49 d of age had a lower number of respiratory cases than those grouped at 56 d of age. It is concluded that moving calves from individual hutches to groups of calves in superhutches immediately after weaning is preferable to waiting an additional 6 d. In addition, moving calves from individual hutches to groups of 8 in superhutches at 49 d of age and starting to reduce MR offering once grouped is preferable to starting to reduce MR while calves are individually housed.     

Performance and visceral tissue growth and development of Holstein calves fed differing milk replacer allowances and starch concentrations in pelleted starter

The objectives of this study were to investigate how milk replacer (MR) allowance and differing concentrations of starch and neutral detergent fiber in starter alters visceral tissue and overall growth of the calf. Calves were randomly assigned to 1 of 4 dietary treatments (n = 12 per treatment) arranged in a 2 × 2 factorial based on daily MR allowance (MRA) and amount of starch in pelleted starter (SPS) as follows: 0.691 kg of MR/d [dry matter (DM) basis] with starter containing low or high starch (12.0% and 35.6% starch, respectively) and 1.382 kg of MR/day (DM) with starter containing low or high starch. All calves were housed in individual pens with straw bedding until wk 5 when bedding was covered to minimize intake. Calves were fed MR twice daily (0700 and 1700 h) containing 24.5% crude protein (DM) and 19.8% fat (DM), and had access to pelleted starter (increased by 50 g/d if there were no refusals before weaning, and then 200 g/d during and after weaning) and water starting on d 1. Calves arrived between 1 and 3 d of age and were enrolled into an 8-wk study, with calves undergoing step-down weaning during wk 7. Intakes were measured daily, and body weight (BW) and blood samples were recorded and collected weekly. Calves were dissected in wk 8 for visceral tissue measurements. Overall, there was increased MR DM intake for the high- (0.90 ± 0.01 kg/d; ± SE) compared with the low-MRA (0.54 ± 0.01 kg/d) calves, whereas starter DM intake increased in low- (0.47 ± 0.05 kg/d) compared with high-MRA (0.20 ± 0.05 kg/d) calves, which was driven by increases in wk 6, 7, and 8. High-MRA calves had increased BW during wk 2, 3, 4, 5, 6, and 7. The difference in BW disappeared by wk 8, with overall average daily gain having a tendency to be increased in high (0.57 ± 0.04 kg/d) compared with low-MRA (0.50 ± 0.04 kg/d) calves, whereas average daily gain was increased in high-MRA calves during wk 2 and 3 and increased in low-MRA calves during wk 7 and 8. There were several differences throughout visceral tissue measurements, but most notably, an increase in rumen mass (i.e., full, empty, and digesta weights) in low- compared with high-MRA calves, as well as in low- compared with high-SPS calves was observed. The length, width, and 2-dimensional area of rumen papillae were also increased in low- (area: 0.88 ± 0.03 mm²) compared with high-MRA (0.46 ± 0.03 mm²) calves. The majority of differences were attributed to increased MR allowance, which contributed to reduced pelleted starter intake by more than 50% and reduced rumen development, whereas differences in starch intake from the completely pelleted starter had minimal effects on overall growth and tissue measurements.     

Effects of physical form of a starter for dairy replacement calves on feed intake and performance

One hundred six female Holstein calves [body weight (BW) = 41.5 ± 0.37 kg and 11.2 ± 0.3 d old] were used to evaluate the effects of physical form of a starter on animal performance and starter intake. Calves were randomly allocated to 2 treatments consisting of either a multiparticle or a pelleted starter. Both starters had exactly the same ingredient and nutrient composition but differed in their physical form. Calves received 4 L/d of the same milk replacer at a 150 g/kg dilution rate in 2 offers of 2 L each until they consumed an average of 300 g/d of starter (as fed) for 2 consecutive days; then the dilution rate was decreased to 120 g/kg until the age of 49 d when milk replacer was limited to 1 daily dose of 2 L until 57 d of age. Calves were kept in individual hutches for at least 1 wk after weaning. Body weight was measured at the beginning of the study and at 49 and 64 d of age. The median perimeters for the multiparticle and pelleted starters were 0.61 ± 0.016 and 2.71 ± 0.082 cm, respectively. Overall starter consumption was greater in calves receiving the multiparticle starter (944.8 ± 30.01 g/d) than in those receiving the pelleted starter (863.9 ± 32.04 g/d). There were no differences in the total milk replacer intake between the 2 treatments. Calf BW when leaving the individual hutches at the end of the study was similar between both treatments. Consequently, feed conversion efficiency was greater in calves consuming the pelleted than the multiparticle starter up to 64 d of age, mainly due to the greater conversion efficiency obtained with the pelleted than with the multiparticle starter after the preweaning period. It is concluded that pelleted starters may result in lower dry feed consumption compared with multiparticle starters, but because final BW was similar in both treatments, feed efficiency of calves consuming pelleted starters may be greater than that of calves consuming multiparticle starters. Therefore, when feeding a starter with similar nutrient composition to the one used in this study, there seems to be an economic advantage associated with feeding the starter in a pelleted form compared with a multiparticle form.     

Effects of milk replacer feeding strategies on performance,ruminal development,and metabolism of dairy calves

Performance, rumen development, and metabolism of male Holstein calves (n = 54) were evaluated according to 1 of 3 liquid feeding strategies: 4 L of milk replacer (MR)/d until 60 d old (4L-60d), 6 L of MR/d until 29 d old and 4 L/d from 30 to 60 d (6L-29d/4L-60d), or 6 L of MR/day until 60 d old (60d-6L). Water and starter were provided ad libitum. Intakes of MR and starter were monitored daily and body weight (BW) weekly. Blood samples for glucose and insulin concentrations and ruminal content samples for volatile fatty acids and ruminal ammonia concentrations were collected at 15, 30, 45, 60, 75, and 90 d of age. Six calves on each treatment were euthanized at 30, 60, and 90 d of age. Empty weights of forestomach and abomasum, papillae length, and mitotic index were measured. Average MR intake/d (expressed as a percent of BW) was greater for calves receiving 6 L/d than for those receiving 4 L/d until 30 d of age. Calves on the 6L-29d/4L-60d had the smallest MR intake from 30 to 60 d old, followed by the 4L-60d and 6L-60d treatments. Starter intake (kg of dry matter/day) did not differ between groups. It increased from 0.065 kg/d in the first month to 0.386 kg/d in the second month, and to 2.065 kg/d after weaning. Weight gain was greater for calves fed more MR in the first month, but no difference was observed during the second month. After weaning, 6L-60d calves had greater rate of weight gain than others and were heavier at 30, 60, and 90 d of age. Weight of empty forestomachs, ruminal pH, and ammoniac nitrogen concentration were not different among groups. Propionate concentration was lower for 6L-60d calves, but acetate and butyrate concentrations were not influenced by MR feeding strategy. Calves fed more MR until d 30 had greater ruminal epithelium mitotic index. The different MR feeding strategies did not influence papillae length or ruminal epithelium thickness. Lesions such as ruminal parakeratosis or hyperkeratosis were not observed. The MR feeding strategy did not affect glucose concentration, but insulin was higher in 6L-60d calves than in the other groups. Glucose concentration increased with age, whereas insulin decreased until 45 d old, and then started to increase until 90 d. In conclusion, MR feeding strategy did not influence ruminal development. Feeding calves 6 L of MR/d over 60 d resulted in greater rate of weight gain without negative effects on starter intake or forestomach development. The weight advantage that 6L-60d calves obtained preweaning was maintained until 90 d of age.     

Influence of dietary fat and protein on body composition of Jersey bull calves

Thirty-nine bull calves between 6 and 9 d of age, were assigned to either baseline slaughter or 1 of 4 diets to determine the influence of dietary fat and protein content, at 2 levels of intake, on growth and body composition changes. Calves were assigned to the following diets a 28.5% protein and 16.4% fat milk replacer [MR; 29/16 (n = 9)], 27.3% protein and 33.4% fat MR [27/33 (n = 8)], 20.6% protein and 20.6% fat MR [20/20 (8)], or whole milk [WM (n = 8)]. Calves fed 27/33, 29/16, and WM received 180 g/d of CP to support 650 g of ADG based on predictions from the 2001 NRC. Calves were fed 3 times daily for 4 wk. Weight, hip height, wither height, heart girth, and body length were measured weekly. Weekly plasma samples were analyzed for plasma urea nitrogen, nonesterified fatty acids, and glucose. A subset of calves from each treatment was killed [29/16 (n = 7), 27/33 (n = 6), 20/20 (n = 6), and WM (n = 5)] at the end of wk 4 of treatment; processed for whole-body analysis of fat, protein, ash, and DM; and compared with baseline slaughter calves to estimate composition of empty BW gain. Calves did not differ in average weekly scour score or medication days. Feed efficiency and ADG were greatest for calves fed WM and least for calves fed 20/20; calves fed 29/16 and 27/33 did not differ. Calves fed 27/33 or WM had the greatest % body fat and gained more grams of fat than calves fed other diets. Calves fed 29/16 or 20/20 had similar % fat in empty body as baseline. Differences in % CP, % ash, or % water in empty body and empty BW gain were not detected. Calves fed 27/33 had a trend toward higher NEFA in wk 1 and 2 than calves fed 29/16 or WM. Growth of calves fed 27/33 and 29/16 were similar except that calves fed 29/16 had lower body fat % than calves fed 27/33. Calves on all diets gained less than predicted by the 2001 NRC.     

Influence of starter crude protein content on growth and body composition of dairy calves in an enhanced early nutrition program

Our objectives were to determine the effect of starter crude protein (CP) content on body composition of male 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 (n = 45) were purchased on the day of birth and assigned to a randomized block design. Eight calves were harvested at baseline and remaining calves were divided among the following 3 dietary treatments: (1) low rate of milk replacer [LMR; 20.6% CP, 21.7% fat; 1.25% of body weight (BW) as dry matter (DM)] plus conventional starter (CCS; 21.5% CP, DM basis); n = 11 calves; (2) high rate of milk replacer (HMR; 29.1% CP, 17.3% fat; 1.5% of BW as DM for wk 1, 2% of BW as DM wk 2–5, 1% of BW as DM wk 6) plus conventional starter; n = 12 calves; and (3) enhanced milk replacer (HMR) plus high-CP starter (HCS; 26% CP, DM basis); n = 14 calves. A subset of calves (n = 8) was harvested on d 2 to provide baseline data. Calves began treatments on d 2 or 3 of age. Calves were weaned at d 42. Starter was available ad libitum. Calves from each treatment were harvested at 5 (n = 18) and 10 (n = 19) wk of age and divided into 4 fractions: carcass; viscera; blood; and head, hide, feet, and tail. Fractions were analyzed for energy, CP, lipid, and ash. Average weekly starter intake did not differ between enhanced treatments. Gain of BW was greater for calves fed HMR than for LMR, but was unaffected by starter CP. Carcass weights at 5 wk were greater for HMR but did not differ between starter CP content. At 10 wk, carcass weights were heavier for HMR and had a greater percentage of empty BW for HMR + CCS than for HMR + HCS. At 10 wk, the weights of reticulorumen and liver were greater for calves fed HMR + HCS than for those fed HMR + CCS. At 5 wk, empty BW gain for HMR contained more water and less fat and ash than in calves fed LMR. At 10 wk, empty BW gain for calves fed HMR + HCS contained a greater percentage of water and less fat than for calves fed HMR + CCS. Plasma β-hydroxybutyrate was greater after weaning for calves fed HMR + HCS than for those fed HMR + CCS. After weaning, calves fed HMR had greater plasma total protein concentration than those fed LMR, and total protein was greater for calves fed HMR + HCS than those fed HMR + CCS. Plasma urea N was greater for calves fed HMR treatments, and postweaning was greater for calves fed HMR + HCS. A high-CP starter had minimal effect on empty BW gain before weaning, but after weaning it tended to increase mass of reticulorumen and liver.     

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.     

Lactoferrin supplementation to dairy calves

Twenty-one Holstein calves (12 bulls, 9 heifers) were used to evaluate the effects of supplemental lactoferrin (0, 1, and 10 g/d) added to colostrum, milk, and milk replacer in a 56-d study. Calves fed lactoferrin (LF) weighed more during wk 2, 3, 4, 5, and 6 than control calves. Calves fed LF had increased preweaning daily weight gains and heart girth gains compared with calves not fed lactoferrin. Calves fed 1 g/d LF had a greater preweaning average daily gain than calves fed 10 g/d of lactoferrin. Hematocrit and serum Fe were unaffected by treatments. Calves were weaned when they had consumed 0.7 kg of calf starter grain for 2 consecutive d and were at least 28 d of age. All calves were weaned by 35 d of age, regardless of starter intake. Calves fed LF consumed more calf starter grain during the preweaning period and met weaning criteria at a younger age. This study indicates that supplementing calf diets with LF is advantageous to calf performance.     

Effect of intensified feeding of heifer calves on growth, pubertal age, calving age, milk yield, and economics

The objective of this study was to determine if increasing the energy and protein intake of heifer calves would affect growth rates, age at puberty, age at calving, and first lactation milk yield. A second objective was to perform an economic analysis of this feeding program using feed costs, number of nonproductive days, and milk yield data. Holstein heifer calves born at the Michigan State Dairy Cattle Teaching and Research Center were randomly assigned to 1 of 2 dietary treatments (n = 40/treatment) that continued from 2 d of age until weaning at 42 d of age. The conventional diet consisted of a standard milk replacer [21.5% crude protein (CP), 21.5% fat] fed at 1.2% of body weight (BW) on a dry matter basis and starter grain (19.9% CP) to attain 0.45 kg of daily gain. The intensive diet consisted of a high-protein milk replacer (30.6% CP, 16.1% fat) fed at 2.1% of BW on a dry matter basis and starter grain (24.3% CP) to achieve 0.68 kg of daily gain. Calves were gradually weaned from milk replacer by decreasing the amount offered for 5 and 12 d before weaning for the conventional and intensive diets, respectively. All calves were completely weaned at 42 d of age and kept in hutches to monitor individual starter consumption in the early postweaning period. Starting from 8 wk of age, heifers on both treatments were fed and managed similarly for the duration of the study. Body weight and skeletal measurements were taken weekly until 8 wk of age, and once every 4 wk thereafter until calving. Calves consuming the intensive diet were heavier, taller, and wider at weaning. The difference in withers height and hip width was carried over into the early post-weaning period, but a BW difference was no longer evident by 12 wk of age. Calves fed the intensive diet were younger and lighter at the onset of puberty. Heifers fed the high-energy and protein diet were 15 d younger at conception and 14 d younger at calving than heifers fed the conventional diet. Body weight after calving, daily gain during gestation, withers height at calving, body condition score at calving, calving difficulty score, and calf BW were not different. Energy-corrected, age-uncorrected 305-d milk yield was not different, averaging 9,778 kg and 10,069 kg for heifers fed the conventional and intensive diets, respectively. However, removing genetic variation in milk using parent average values as a covariate resulted in a tendency for greater milk from heifers fed the intensive diet. Preweaning costs were higher for heifers fed the intensive diet. However, total costs measured through first lactation were not different. Intensified feeding of calves can be used to decrease age at first calving without negatively affecting milk yield or economics.     

Effects of milk replacer allowances and levels of starch in pelleted starter on nutrient digestibility,whole gastrointestinal tract fermentation,and pH around weaning

The objectives of this study were to examine the effects of pelleted starter diets differing in starch and neutral detergent fiber (NDF) content when fed differing levels of milk replacer (MR) on nutrient digestibility, whole gastrointestinal tract fermentation, pH, and inflammatory markers in dairy calves around weaning. Calves were randomly assigned to 1 of 4 dietary treatments (n = 12 per treatment) in a 2 × 2 factorial design based on daily MR allowance and amount of starch in pelleted starter (SPS): 0.691 kg of MR per day [dry matter (DM) basis] with starter containing low or high starch (12.0% and 35.6% starch on DM basis, respectively), and 1.382 kg of MR per day (DM) with starter containing low or high starch. All calves were housed in individual pens with straw bedding until wk 5 when bedding was covered. Calves were fed MR twice daily (0700 and 1700 h) containing 24.5% crude protein (DM) and 19.8% fat (DM), and had access to pelleted starter (increased by 50 g/d if there were no refusals before weaning and then 200 g/d during and after weaning) and water starting on d 1. Calves arrived between 1 and 3 d of age and were enrolled into an 8-wk study, with calves undergoing step-down weaning during wk 7. Starting on d 35, an indwelling pH logger was inserted orally to monitor rumen pH until calves were dissected at the end of the study in wk 8. Higher SPS calves showed an increase in rumen pH magnitude (1.46 ± 0.07) compared with low SPS calves (1.16 ± 0.07), a decrease in rumen pH in wk 8 (high SPS: 5.37 ± 0.12; low SPS: 5.57 ± 0.12), and a decrease in haptoglobin in wk 8 (high SPS: 0.24 ± 0.06 g/L; low SPS: 0.49 ± 0.06 g/L). The majority of differences came from increased starter intake in general, which suggests that with completely pelleted starters the differences in starch and NDF do not elicit drastic changes in fermentation, subsequent end products, and any resulting inflammation in calves around weaning.     

Effects of feeding milk replacer at a moderate rate,ad libitum,or with a step-up program on Holstein calf growth performance to 4 months of age

The objective of this study was to evaluate 3 milk replacer (MR) feeding programs on calf performance to 4 mo of age. Male Holstein calves (n = 48; 2–3 d old) were randomly assigned to either a moderate rate of MR (MOD; 0.66 kg/d for 39 d, then 0.33 kg/d for 3 d), an ad libitum rate of MR (ADLIB; offered twice daily between 0630 and 0830 h and between 1430 and 1630 h for 35 d, 0.66 kg/d for 4 d, and 0.33 kg/d for 3 d), or a step-up rate of MR (STEPUP; increased from 0.32 to 0.62 kg/d in first 12 d, 0.66 kg/d for 27 d, and 0.33 kg/d for 3 d). The MR (25% CP, 18% fat) was fed twice daily to d 39 and once daily thereafter. During the nursery phase (0–56 d), calves were housed in individual pens and offered textured starter (40% starch, 21% CP on a DM basis) and water ad libitum. Calf body weight (BW) was measured initially and weekly thereafter. Hip widths (HW) were measured initially and every 2 wk thereafter. In the grower phase, (57–112 d), calves were grouped by previous treatment and moved to group pens (4 calves/pen). The same starter used in the nursery phase was blended with 5% chopped grass hay and offered ad libitum. Calf BW and HW were measured on d 56, 84, and 112. Total MR intake per calf averaged 27, 51, and 25 kg for MOD, ADLIB, and STEPUP programs, respectively, with a range of 42 to 63 kg for ADLIB. In the nursery phase, starter intake and feed efficiency were less for ADLIB versus MOD, whereas fecal scores and abnormal fecal score days were greater for calves fed ADLIB versus MOD. Calves fed STEPUP had lesser average daily gain than calves fed MOD. During the grower phase, initial BW was greater for ADLIB versus MOD, though final BW was not different between MOD and ADLIB or STEPUP. Calves previously fed MOD had greater average daily gain, feed efficiency, and HW change than calves fed ADLIB. In this study, feed efficiency was lower when MR was fed ad libitum, and growth advantages observed at 2 mo were lost by 4 mo of age.     

Effects of 2 liquid feeding rates over the first 3 months of life on whole-body energy metabolism and energy use efficiency of dairy calves up to 5 months

Intensified milk replacer (MR) feeding in calves has nutritional long-term effects and is suggested to increase milk production later in life. However, the underlying mechanisms are not completely understood. The aim of our study was to investigate whether MR feeding intensity has long-term effects on energy metabolism and energy use efficiency of dairy calves. Newborn female Holstein calves (n = 28) were randomly assigned to 2 liquid feeding groups offered daily either 10% of body weight (BW) colostrum followed by 10% of BW MR (10%-MR) or 12% of BW colostrum followed by 20% of BW MR (20%-MR). Calves were housed individually. Weaning was completed by the end of wk 12. Hay and calf starter were fed from d 1 until the end of wk 14 and 16, respectively. A total mixed ration was fed from wk 11 onward, and the metabolizable energy intake (MEI) was determined daily. Energy metabolism of calves was measured in respiratory chambers before weaning in wk 6 and 9, and after weaning in wk 14 and 22. The MEI/BW^0.75 was higher before weaning but lower during and shortly after weaning in 20%-MR calves. During the preweaning period, the 20%-MR animals had higher average daily gain, BW, back fat thickness and muscle diameter, but lower plasma β-hydroxybutyrate concentrations. The group difference in average daily gain ceased in wk 9, differences in back fat thickness and muscle diameter ceased after weaning, whereas difference in BW^0.75 persisted until wk 23. The energy conversion ratio (BW gain/MEI) was not different before weaning, but was lower during and after weaning in 20%-MR calves. The higher MEI and BW^0.75 in 20%-MR calves resulted in higher heat production (HP), as well as in higher carbohydrate oxidation (COX) and fat oxidation during the preweaning period. Gas exchange variables normalized to BW^0.75 or MEI differed between groups only during preweaning. The energy balance was lower in 10%-MR calves in wk 6 and 9. The HP/BW^0.75 and COX/BW^0.75 were higher, whereas HP/MEI was lower in 20%-MR calves in wk 6. When normalized to BW^0.75 and MEI, HP in wk 6 and 9, and COX in wk 9 was lower in 20%-MR calves. In conclusion, 20%-MR calves showed greater efficiency estimates preweaning, but this effect did not occur after weaning, suggesting that energy use efficiency does not persist until later stages in life.     

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).     

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.     

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.     

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.     

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.