Milk Replacer Feeding Rate Research Articles

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.

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.

Effects of milk replacer feeding rate and fat content on Jersey calf nutrient digestion and performance to 4 months of age

This study evaluated effects of milk replacer (MR) feeding rate and fat concentration in MR on total-tract digestion (TTD) and growth performance in Jersey calves. Jersey heifer calves (n = 100, 2 blocks of 50; initially 30 ± 3.0 kg of body weight; 4-11 d of age) were randomly assigned to 1 of 4 treatments in a 2 × 2 factorial arrangement of MR feeding rate [454 g for 42 d, and 227 g for 7 d (MOD); or 454 g for 7 d, 681 g for 35 d, and 341 g for 7 d (HI), as-fed basis] and MR fat content (17 or 24% fat as-fed basis). Milk replacers (24% crude protein as-fed basis) were reconstituted to 14% solids and fed in 2 equal feedings for 42 d, and then mornings only for 7 d. Textured calf starter (21% crude protein, 40% starch, dry matter basis) and water were offered for ad libitum consumption. From d 57 to 112, calf starter was mixed with 5% chopped grass hay. Calves were housed individually to d 56 and housed in groups (4-5 calves/pen) from d 57 to 112. Estimates of TTD were measured in 5 calves/treatment (block 1) at wk 3 of the study using acid-insoluble ash as an indigestible marker. From 0 to 56 d, calf starter intake (CSI) was greater for MOD vs. HI and 17 versus 24% fat; average daily gain was greater for HI versus MOD; and hip width change was greater for 17 versus 24% fat. Estimates of organic matter TTD were greater for HI versus MOD, but neutral detergent fiber TTD was greater for MOD versus HI and for 17 versus 24% fat. From 57 to 112 d, hip height change was greater for MOD versus HI, and hip width change was greater for 17 versus 24% fat. In this study, feeding Jersey calves more MR improved preweaning average daily gain, but had a negative effect on CSI and likely rumen development, as neutral detergent fiber TTD was reduced at 3 wk and frame growth was reduced from d 57 to 112. This resulted in similar final calf body weights between MR feeding rates at the end of the study. No benefits were observed for feeding more fat in MR as CSI or for NDF digestibility, and frame growth was reduced.

Longitudinal assessment revealed the shifts in rumen and colon mucosal-attached microbiota of dairy calves during weaning transition

The objectives of this study were to investigate the shifts in rumen and colon mucosa-associated microbiota in dairy calves fed a high milk replacer feeding rate before and after weaning and to determine whether such shifts are associated with tissue physiological measures. Longitudinal biopsy was performed to collect rumen and colon mucosal tissues of 4 ruminally cannulated Holstein dairy bull calves (weaned at 6 wk of age) at the end of wk 5 (before weaning), 7 (weaning adaptation) and 12 (after weaning), and were used to assess mucosa-associated microbiota and their changes using amplicon sequencing. Both rumen and colon mucosa-associated bacterial communities shifted during the weaning process, as evidenced by their clear separation among 3 different weaning periods and increased α diversity (Shannon and Chao1 indices) during weaning transition. Among the 3 dominant bacterial phyla identified (relative abundance >1.0%), the relative abundance of Proteobacteria and Bacteroidetes decreased in the rumen mucosa, whereas the relative abundance of Firmicutes increased in both rumen and colon mucosa during weaning transition. In the rumen mucosa, Campylobacter (0.6-22.1%) gradually became prevalent during weaning transition, whereas Succinivibrio (6.2-10.3%) and Prevotella 1 (4.7-10.5%) were dominant regardless of weaning transition. In the colon mucosa, Bacteroides (12.8-25.4%) was dominant during weaning transition, although its relative abundance decreased after weaning. In the meantime, relative abundance of uncultured Lachnospiraceae increased from 2.2% to 25.7% during this period. In addition, genera Pyramidobacter (in the rumen mucosa) and Lachnoclostridium (in the colon mucosa) were positively correlated with rumen papilla surface area and colon mucosal thickness, respectively. Moreover, genera Ruminococcaceae UCG-005 and Sharpea in the rumen mucosa were positively correlated with the molar proportion of propionate and butyrate, respectively. Overall, our findings revealed that rumen and colon mucosa-associated bacterial communities altered in response to the weaning transition, and some bacterial taxa in these communities may have positive effects on rumen and colon mucosa development during this period.

Preweaning to postweaning rumen papillae structural growth, ruminal fermentation characteristics, and acute-phase proteins in calves

This study evaluated pre- to postweaning ruminal structural development, fermentation characteristics, and acute-phase protein levels in calves with a high milk replacer (MR) feeding rate prior to weaning. Six ruminally cannulated Holstein bull calves were fed MR (150 g/L) at 15% of body weight (BW) in 2 equal volumes daily. Volumes were adjusted weekly based on BW. Calves were weaned using a 1-step weaning method, with MR decreased by 50% at the end of wk 5 and full weaning at the end of wk 6. Calf starter, chopped straw, and water were offered ad libitum. Intake was recorded daily, and BW was recorded weekly. From wk 5 to 12, ruminal pH was continuously measured using a ruminal pH bolus. Ruminal fluid was collected weekly from wk 5 to 12 for measurement of short-chain fatty acid concentrations and quantification of total bacteria and protozoa. Rumen papillae were obtained at wk 5, 6, 7, 8, and 12 for histological analysis. Serum amyloid A and lipopolysaccharide-binding protein were measured weekly. Data were analyzed using GLIMMIX procedure of SAS (SAS Institute Inc., Cary, NC), with week as a fixed effect and calf as a random effect. During the weaning step-down, starter intake was 3-fold higher and continued to increase until wk 12. Body weight increased from birth to wk 12; however, BW did not change during wk 6, 7, and 8, possibly due to low metabolizable energy intake caused by the weaning strategy. Preweaning ruminal pH was below 5.8 for approximately 936.3 ± 125.99 min/d, implying ruminal acidosis. Furthermore, ruminal pH below 5.8 reached a peak at wk 8 with 1,203.9 ± 227.65 min/d below pH 5.8 and slowly decreased to 388.1 ± 189.82 min/d below pH 5.8 at wk 12. Papillae surface area, length, and width increased during wk 12 compared with wk 5. Corneum thickness increased by week, whereas spinosum/basale thickness only increased during wk 8 compared with wk 5. The acute-phase protein concentration was highest at wk 1 and then decreased and remained constant until wk 12. In conclusion, even before step-down weaning, calves experienced ruminal acidosis despite low starter intake. Further, the observed prolonged ruminal pH depression suggests that dietary rumen adaptation after weaning can take several weeks in calves with a high MR feeding rate preweaning. The prolonged depressed ruminal pH did not affect acute-phase proteins and this finding, along with the other results, suggests that rumen epithelium barrier integrity is not compromised during weaning.

Growth performance of newborn dairy calves fed a milk replacer with 2 protein concentrations at 2 feeding rates

ABSTRACT Objective The objective was to evaluate the growth performance by calves fed a conventional milk replacer (MR) or modified accelerated MR (24% CP) to prevent the slump in postweaning calf starter intake and feed efficiency. Materials and Methods A total of 104 (1 to 5 d old) Holstein heifer calves (39.3 ± 0.66 kg) were assigned randomly to 1 of 4 MR treatments to evaluate preweaning (1 to 42 d) and postweaning (43 to 56 d) performance in a 2 × 2 factorial arrangement of CP concentrations [20% CP or 24% CP high protein (HP) with feeding rates (FR) of 0.57 or 0.68 kg/d]. Treatments were MR fed at 15% solids (as fed): (1) control (CP1): a 20% CP:20% fat MR fed at 0.284 kg 2×/d for 35 d; (2) CP2: the 20:20 MR fed at 0.34 kg 2×/d for 35 d; (3) HP1: a 24:20 MR fed at CP1 rate; and (4) HP2: the 24:20 MR fed at CP2 rate. Results and Discussion No interactions of CP by FR were detected for growth parameters. During 1 to 14 d, calves fed higher MR FR (CP2 and HP2) had greater (P 0.10). Intakes of calf starter from 1 to 56 d were similar (P > 0.10) for calves fed MR with different CP concentrations (0.77 and 0.78 kg/d), whereas calf starter intake (0.81 and 0.74 kg/d) was reduced (P 0.01) for calves fed different CP concentrations (0.54 and 0.55 kg/kg) but were improved when fed higher MR FR (0.53 and 0.56 kg/kg). However, a trend (P Implications and Applications Feeding calves a conventional MR (20%CP:20% fat) at different FR with different CP concentrations resulted in similar performance. Feeding a higher CP MR (24% CP:20% fat) at higher FR did not affect preweaning gain of dairy calves.

Effects of milk replacer feeding rates on growth performance of Holstein dairy calves to 4 months of age, evaluated via a meta-analytical approach

Our objective was to evaluate effects of feeding milk replacer (MR) at 2 feeding rates on digestion, intake, and growth of young dairy calves, via a meta-analytical approach using individual data. A database was developed from 10 published studies from the Nurture Research Center (Provimi; Brookville, OH), in which 26 dietary treatments and 491 calves from 0 to 8 wk of age in 13 nursery trials, and 22 dietary treatments and 485 calves from 8 to 16 wk of age in 13 grower trials occurred. Male Holstein calves (n = 491; initial body weight 42.8 ± 4.9 kg) were randomly assigned to 1 of 2 treatments: (1) moderate (MOD), 0.64 to 0.66 kg of dry matter (DM)/d for the first 35 to 39 d, followed by half the allotment per d for 3 to 7 d, fed at the a.m. feeding only; (2) high (HI), 0.92 to 1.07 kg of DM/d for the first 35 to 44 d, followed by half the allotment per d for 5 to 7 d, fed at the a.m. feeding only. Calves were weaned at 6 to 7 wk of age. Milk replacer ranged from 24.8 to 28.6% crude protein (CP) and 17.6 to 20.2% fat; starter ranged from 17.3 to 22.2% CP and 3.0 to 4.3% fat on a DM basis. On d 56 calves (n = 485) moved into pens (4 calves/pen) by treatments and were fed starter (19.4 to 22.3% CP and 3.4 to 4.6% fat, DM basis) blended with 5% hay until d 112. In all nursery trials (d 0 to 56), calves fed MOD had lower average daily gain (ADG; 0.634 vs. 0.545 kg/d), gain/DMI (0.488 vs. 0.466 kg/kg), and hip width change (0.069 vs. 0.064 cm/d), but greater starter intake (0.473 vs. 0.696 kg/d) compared with calves fed HI. Apparent total-tract digestibility of DM (73.3 vs. 78.4%), organic matter (OM; 74.1 vs. 79.0%), CP (74.8 vs. 78.9%), and neutral detergent fiber (NDF; 40.8 vs. 53.9%) were greater for calves fed MOD vs. HI when estimated during wk 8. In all grower trials (d 56 to 112), ADG (1.015 vs. 0.976 kg/d), gain/DMI (0.375 vs. 0.349 kg/kg), and hip width change (0.089 vs. 0.081 cm/d) were greater, but dry feed intake per kg of BW0.75 did not differ (87.8 vs. 88.2 g/d) for calves previously fed MOD vs. HI. Apparent digestibility of DM (78.7 vs. 76.0%), OM (79.8 vs. 77.0%), CP (80.5 vs. 78.4%), and NDF (54.8 vs. 45.8%) were greater for calves fed MOD vs. HI when estimated between wk 11 to 13. Over the entire 112-d period, calves fed MOD had lower ADG (0.805 vs. 0.784 kg/d) but tended to have greater hip width change (8.415 vs. 8.589 cm) compared with calves fed HI. Under the conditions of this study, feeding higher MR rates caused calves to partially lose growth advantage during the weaning transition and further decreased BW gain and structural growth in the grower period (d 56 to 112), which could be due to reductions in nutrient digestibility as a result of feeding more MR.

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.

Effects of milk replacer feeding rate and long-term antibiotic inclusion in milk replacer on performance and nutrient digestibility of Holstein dairy calves up to 4 months of age

The objectives of this study were to evaluate calf performance and diet digestibility when feeding a milk replacer (MR; 25% crude protein, 18% fat, dry matter basis) at a moderate (MOD) and high (HI) rate, along with MOD with neomycin-oxytetracycline inclusion (1.43 each g/kg; NTMOD). Male Holstein calves (n = 48; 45 ± 1.0 kg of body weight; 3 to 4 d of age) were housed in individual pens for 56 d. All calves were initially fed 0.66 kg of dry matter from MR for the first p.m. and following a.m. feeding, then randomly assigned to 1 of 2 feeding programs: (1) 0.66 kg of dry matter/d for first 39 d divided into 2 equal a.m. and p.m. meals and 0.33 kg for 3 d fed once daily in the a.m. feeding only (MOD, NTMOD); (2) 0.85 kg of dry matter/d for the first 4 d divided into 2 equal a.m. and p.m. meals, 1.07 kg of dry matter/d for the next 31 d divided into 2 equal a.m. and p.m. meals, and 0.48 kg for 7 d fed once daily in the a.m. feeding only (HI). Calves were fed a textured starter containing whole grains (20% crude protein, 43% starch, dry matter basis). Fecal samples were collected for 5 individual calves per treatment between d 47 to 51 to estimate digestibility. Calves were moved into groups by treatment (4 calves/pen) at 56 d and fed the same starter blended with 5% hay until d 112. Data were analyzed as a completely randomized design with repeated measures when applicable using mixed models. Milk replacer dry matter intake averaged 27.4 kg for MOD and NTMOD and 40.3 kg for HI per calf. Preweaning starter intake was less for calves fed HI versus MOD. Preweaning calf BCS change was greater for calves fed HI versus MOD. Preweaning medical treatment days were fewer for calves fed NTMOD versus MOD. Postweaning starter intake was less for calves fed HI versus MOD. Postweaning average daily gain was less for calves fed NTMOD versus MOD. Over the 56-d nursery trial, calves fed HI had less starter intake than calves fed MOD. Digestibility of dry matter, organic matter, acid detergent fiber, and neutral detergent fiber were greater for calves fed MOD versus NTMOD or HI during d 47 to 51 postweaning. Additionally, digestibility of fat was greater for calves fed MOD versus HI. During d 56 to 112, hip width change was greater for calves fed MOD versus NTMOD or HI. Over 0 to 112 d, body weight gain was 100, 98, and 102 kg, whereas hip width change was 10.2, 9.0, and 9.2 cm for calves fed MOD, NTMOD, and HI, respectively. Any preweaning improvements from feeding NTMOD or HI over MOD were lost during the postweaning period, which could be partially explained by reductions in diet digestibility.

Effect of milk replacer feeding rate, age at weaning, and method of reducing milk replacer to weaning on digestion, performance, rumination, and activity in dairy calves to 4 months of age

The objectives of this study were to evaluate calf performance, diet digestibility, and rumination activity when feeding 4 milk replacer (MR) feeding programs. Male Holstein calves (n = 96; 43 ± 1.2 kg of body weight; 1 to 2 d of age) were housed in individual pens for 56 d. Calves were fed a common MR [25% crude protein (CP), 17% fat, dry matter (DM) basis]. Feeding programs were (1) 0.66 kg of DM/d of MR and weaning at 42 d (MOD6); (2) up to 1.09 kg of DM/d of MR weaned at 42 d (HIGH6); (3) up to 1.09 kg of DM/d of MR weaned at 53 d (HIGH8); and (4) up to 1.09 kg of DM/d of MR and gradually weaned from d 35 to 53 (GRAD8). Calves were fed a textured starter containing whole grains with 20% CP and 37% starch (DM basis). From 38 to 56 d of age, 4 calves/treatment had ear tag accelerometers fitted to provide measurements for eating, rumination, and activity. Calves were moved into groups by treatment (4 calves/pen) at 56 d and fed the same starter blended with 5% hay. Fecal samples were collected for individual calves between d 31 to 35, 45 to49 (MOD6 and HIGH6 only), and 56 to 60 from 5 calves/treatment. Fecal samples were collected by pen from d 80 to 84 and 108 to 112. Data were analyzed as a randomized complete block design with repeated measures when appropriate. Preplanned contrasts of MOD6 versus others, HIGH6 versus HIGH8, and HIGH8 versus GRAD8 were used to separate the means. Calves fed MOD6 were 3.4 kg lighter at 56 d than calves fed other treatments. Starter intake was greatest for MOD6 compared with other treatments (0.78 vs. 0.43 kg/d) from 0 to 56 d. Hip width and body condition score change from 0 to 56 d were similar among treatments. Average time ruminating, eating, and activity did not differ among treatments. Total-tract digestibility of DM, OM, CP, and fat were least for calves fed MOD6 versus other treatments on d 35, whereas NDF and starch digestibility were greatest for MOD6 at d 35. Digestibility of ADF and NDF were also greatest for MOD6 at d 49 (compared with HIGH6 only) and 60. From d 56 to 112, calves previously fed MOD6 had greater ADG versus other treatments. At 84 d, DM, OM, CP, NDF, ADF, and fat digestibility were greatest for calves fed MOD6 versus others. Calves fed HIGH6 and GRAD8 had greater digestibility of NDF and ADF compared with HIGH8 at 84 d. At 112 d, digestibility was similar among treatments. Calves were not different in BW and hip width at 112 d, with growth driven by less digestion of DM and fiber around and after weaning for calves fed >0.66 kg of MR. Gradual weaning did improve postweaning digestion.

Effects of egg yolk inclusion, milk replacer feeding rate, and low-starch (pelleted) or high-starch (texturized) starter on Holstein calf performance through 4 months of age

The objectives of this research were to evaluate milk replacer (MR) feeding rates, alternative protein and fat sources in MR, and calf starter starch concentration and their effects on calf performance to 4 mo of age. Male Holstein calves (42.6 ± 1.2 kg of body weight; n = 192) were assigned at 3 d of age to 1 of 8 treatments in a randomized complete block design with a 2 × 2 × 2 factorial arrangement of treatments. Factors tested from d 0 to 56 (nursery) were low or high MR feeding rates, 0 or 10% inclusion of spray-dried egg yolks in MR, and low- or high-starch calf starter. The low MR rate was 0.66 kg of dry matter (DM) fed for 39 d followed by 0.33 kg of DM for 3 d. The high MR rate was 0.87 kg of DM fed for 5 d, 1.08 kg of DM for 37 d, and 0.43 kg of DM for 7 d. The MR contained 27.5% crude protein and 19.6% fat (DM basis) and starters were 21.2% crude protein; low starch was a complete pellet with 10.2% starch, and high starch was textured using whole corn and oats with 43.3% starch. From d 56 to 112 (grower), calves were randomly assigned to pens (4 calves/pen) maintaining MR rate and starch content while stratifying yolk treatments within pen, resulting in a 2 × 2 factorial arrangement. Starter was blended with 5% chopped hay during the grower trial. Fecal scores and medical treatments were recorded daily. In the nursery trial, calves were weighed initially and weekly thereafter. Hip width and body condition score (BCS) were measured initially and every 2 wk thereafter. In the grower trial, body weight, hip width, and BCS were measured on d 56, 84, and 112. Data were analyzed as repeated measures with calf (nursery) or pen (grower) as the experimental unit. Calf average daily gain, hip width, and BCS change were greater for calves fed high versus low MR, 0 versus 10% yolk, and high versus low starch in the nursery. In the grower trial, calves fed low MR and high starch had the greatest average daily gain (1.09 vs. 0.87 kg/d) and hip width change (5.4 vs. 3.9 cm) compared with calves fed low MR and low starch with other treatments intermediate. From 0 to 112 d, calves fed high MR had 9% greater body weight gain and 4% greater hip width change than calves fed low MR, yet nutrient efficiency was similar despite 80% more MR intake than calves fed low MR. Additionally, calves fed high-starch starter achieved 18% greater body weight gain and 17% greater hip width than calves fed low starch starter overall, a more than 2-fold greater response than the effect of MR feeding rate.

1461 Effects of milk replacer feeding rate, egg yolk inclusion in milk replacer, and calf starter starch content on Holstein calf performance through four months of age

1461 Effects of milk replacer feeding rate, egg yolk inclusion in milk replacer, and calf starter starch content on Holstein calf performance through four months of age

Effect of milk replacer feeding rate and functional fatty acids on dairy calf performance and digestion of nutrients

Calves fed large amounts of milk replacer (MR) gain more body weight preweaning than calves fed less MR; however, postweaning growth may be reduced because of impaired digestion of nutrients. This was explored in the current research, as was the inclusion of functional fatty acids (NT) that could ameliorate some poor growth and digestion issues in calves fed large amounts of MR. Two MR rates [moderate (MOD) or aggressive (AGG)] with and without NT were compared using 48 male Holstein calves initially 3d old (43±1.5kg of body weight) randomly assigned to treatments. The MOD rate was fed at 0.66kg of dry matter (DM) for 49d. The AGG rate was fed for 4d at 0.66kg of DM, 4d at 0.96kg of DM, then 34d at 1.31kg of DM, followed by 0.66kg of DM for the last 7d. Calves were completely weaned at 49d. The MR contained 27% crude protein and 17% fat. The textured starter was 20% crude protein. Starter and water were fed free-choice for the first 56d when calves were housed in individual pens. From 56 to 112d, calves were grouped (4 calves/pen), maintaining the same MR rate and NT treatments, and fed starter blended with 5% chopped grass hay free-choice with free-choice water. Digestibility was estimated from fecal collections made on d 19 to 23, 40 to 44, and 52 to 56. Data were analyzed as a completely randomized design with a factorial arrangement of MR rate and NT using repeated measures with a mixed procedure. Fiber and starch digestion increased with age and was lower for AGG versus MOD. Calf average daily gain and hip width change were greater before approximately 6wk of age for AGG versus MOD, but this was reversed from approximately 6 to 16wk. Calves fed AGG had lower average daily gain per unit intake of DM, crude protein, and metabolizable energy from 8 to 16wk than calves fed MOD. Preweaning starter intake was less for calves fed AGG versus MOD. Calves fed AGG had greater body weight gain than MOD over 112d, but hip width change did not differ. Feeding NT improved digestibility of organic matter, DM, neutral detergent fiber, and acid detergent fiber (over 50% improvement for neutral detergent fiber and acid detergent fiber), which resulted in 10.7kg (13%) more body weight gain and 1.4cm (16%) more hip width change over 112d. This was a greater improvement in growth than the difference in AGG and MOD programs over 112d.

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 ± 1kg 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), 51.5g 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), 55.0g 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 Feeding Rate of Milk Replacers and Bedding Material for Calves in a Cold, Naturally Ventilated Nursery

AbstractDifferent milk replacer (MR) programs and rates were evaluated with different bedding materials during cold temperatures. A MR (26% CP and 17% fat) was fed at 0.681 to 0.908 kg/d (study 1) or a MR (20% CP and 20% fat) was fed at 0.454 to 0.681 kg/d (study 2A) to calves bedded with hardwood shavings or wheat straw. In study 2B, calves from study 2A were grouped in pens by previous MR rate and fed a common diet for 28 d. In study 3, calves were fed A) a MR (26% CP and 17% fat) at 0.681 kg/ d for 42 d, B) or MR (26% CP and 17% fat) stepped up to 0.908 kg/d then reduced to 0.681 kg/d for 21 d, or C) 0.817 kg/d of a MR (22% CP and 27% fat) for 21 d and then fed 0.681 kg/d of a MR (26% CP, 17% fat) for 21 d. Calves were weaned at 42 d. In Studies 1 and 2A, ADG was unchanged and starter intake declined linearly (P < 0.05) from 0 to 56 d as MR fed increased. Straw bedding supported 5 to 12% faster (P < 0.05) ADG from 0 to 56 d than shavings. In study 2B, ADG and starter intake declined linearly (P < 0.05) as previous MR fed increased. In study 3, calves fed MR stepped up to 0.908 kg/d and then reduced to 0.681 kg/d for 21 d yielded 5% faster (P < 0.05) ADG from 0 to 56 d than calves fed MR at 0.681 kg/d for 42 d. Choice of bedding material was as or more effective than MR feeding rate in improving ADG of calves in cold temperatures.