Effects of starch content of calf starter on growth and rumen pH in Holstein calves during the weaning transition

The objective of this study was to evaluate the effects of substituting high fiber byproducts for dry ground corn in calf starter on growth and rumen pH during the weaning transition. Holstein bull calves were raised on an intensified nursing program using milk replacer containing 26% CP and 18% fat. Calves were fed a texturized calf starter containing either dry ground corn at 18.8% of dry matter (DM; CRN), beet pulp replacing dry ground corn at 10.2% dietary DM (BP), or triticale dried distillers grains with solubles replacing dry ground corn and high-protein feedstuffs at 18.6% of dietary DM (DDGS) in the pellet; treatment calf starters differed only in the pellet portion. Starch concentrations of CRN, BP, and DDGS were 35.3, 33.4, and 31.4%, respectively. After a calf consumed 2.50 kg of starter for 3 consecutive days, a small ruminant rumen pH data logger was inserted orally and rumen pH was measured continuously for 4d. Calves were then killed and rumen fluid was sampled to determine volatile fatty acid profile. No difference was found in overall average daily gain or growth rates of hip height, withers height, and heart girth. During the weaning transition, rate of increase in calf starter intake was greater for calves fed DDGS compared with those fed CRN (87.7 vs. 77.5 g/d), but lower for calves fed BP compared with CRN (68.1 vs. 77.5 g/d). The area under pH 5.8 (470 vs. 295 min × pH/d) or pH 5.2 (72.7 vs. 16.4 min × pH/d) was greater for calves fed DDGS than those fed CRN. Rumen pH profile was not affected by BP treatment compared with CRN, but calves fed BP tended to have greater water intake than those fed CRN (6.6 vs. 5.8 L/d). Volatile fatty acid profile was not affected by treatment with the exception of molar proportion of butyrate, which tended to be lower for calves fed BP compared with those fed CRN (15.0 vs. 16.6%). Hay intake was positively correlated to mean rumen pH for calves used in this study (r=0.48). Decreasing dietary starch concentration did not mitigate rumen acidosis in calves during weaning transition, and low rumen pH did not adversely affect growth during the weaning transition.     

Effects of adding extra molasses to a texturized calf starter on rumen development, growth characteristics, and blood parameters in neonatal dairy calves

A texturized calf starter containing 5 (control) or 12% molasses [on a dry matter (DM) basis] was fed to dairy calves to determine effects on intake, growth, blood parameters, and rumen development. Forty-six Holstein calves (26 male and 20 female) were started at 2 +/- 1 d of age and studied for 42 d. Starter DM intake was measured and fecal scoring was conducted daily. Growth and blood parameter measurements were conducted weekly. A subset of 6 male calves (3 per treatment) was euthanized at 4 wk of age, and rumen tissue sampled for rumen epithelial growth measurements. Starter sugar content was significantly increased in the starter containing extra molasses. Postweaning and overall starter DM intake, overall total DM intake, daily heart girth change, and final heart girth were significantly decreased, whereas overall average daily gain tended to decrease when calves received starter containing 12% molasses. However, blood volatile fatty acid concentrations were significantly increased when calves received a starter containing 12% molasses. No significant differences were observed between calves receiving starters containing 5 or 12% molasses for all other variables. The data indicates that adding extra molasses to a texturized calf starter decreases intake and structural growth, possibly causing decreased weight gain, but increases blood volatile fatty acid concentrations and slightly increases ruminal development. However, feed handling and physical prehension problems in addition to the negative influences on calf growth and intake do not support increasing starter molasses content to 12% of the supplement.     

Effects of corn processing, particle size, and diet form on performance of calves in bedded pens

In a series of 5 trials, Holstein calves from zero to 12 wk old were housed in pens bedded with straw and fed diets to evaluate physical form of starters containing different processed corn on calf performance. Starters were formulated to have similar ingredient and nutrient compositions. Calves, initially less than 1 wk old, were housed in individual pens through 8 wk and weaned at 6 wk in trial 1 and at 4 wk in trials 2 and 3. In trials 4 and 5, calves initially 8 wk old were housed in group pens (6 calves/pen) from 8 to 12 wk. Trial 1 compared feeding calves a pelleted versus textured starter. Trial 2 compared feeding calves a textured starter versus feeding half meal starter with half textured starter. Trial 3 compared feeding calves textured starters containing whole, steam-flaked, or dry rolled corn. Trial 4 compared feeding calves textured starters containing steam-flaked versus dry rolled corn. Trial 5 compared feeding calves textured starters containing whole or dry rolled corn. Measurements included average daily gain (ADG), starter intake, feed efficiency, hip width change, body condition score change, fecal scores, and medical treatments. Physical form of starter feed did not affect any measurements in trials 1, 3, 4, and 5. In trial 2, calves fed starters manufactured with large amounts of fines had 11% less feed intake and 6% slower ADG than calves fed a textured starter. When starters contained similar ingredient and nutrient contents, manufacturing processes did not affect calf performance unless the diet contained a significant amount of fines, which reduced intake and ADG.     

Effect of a mixture of steam-flaked corn and soybeans on health, growth, and selected blood metabolism of Holstein calves

The objective of the experiment was to evaluate the effects of steam-flaked corn grains and soybeans on calf health, growth, and selected blood parameters. Holstein bull calves (n = 30, approximately 7 ± 3 d of age) were purchased from local dairy farms and offered milk, starter diets, and hay, and were then assigned to the experiment at 21 ± 3 d of age. Calves were blocked into 3 treatments by birth date and body weight and randomly assigned to receive fresh milk and a commercial pelleted starter containing extruded corn and soybeans (ECS), steam-flaked corn and soybeans (SFCS), or ground corn and soybeans (GCS). The experiment was conducted with calves from 3 to 13 wk of age. Body weight, calf starter intake, milk intake, total dry matter intake, and body structural growth were not significantly influenced by corn and soybean processing during the study; however, feed efficiency was significantly improved by the SFCS treatment. Average daily gain generally decreased during the weaning week for all treatments, but did not differ significantly among treatments. Health incidences for calves fed the SFCS starter were lower than those fed the other 2 treatments. The blood hematocrit was higher for calves fed the SFCS starter than for those fed the GCS and ECS starters during wk 6 to 11. The concentration of plasma β-hydroxybutyrate was higher for the calves fed the GCS and SFCS treatments than for those fed the ECS treatment during wk 6 to 13, but lower during wk 4 and 5. Plasma glucose concentrations decreased remarkably with increasing calf age but were not affected by corn and soybean processing. Plasma nonesterified fatty acids were influenced by calf age, and higher NEFA concentration was observed in the SFCS treatment than in the other 2 treatments during wk 5 to 9. Calves consuming the SFCS starter had similar average daily gain, milk intake, starter intake, total dry matter intake, and body structure, but had improved feed efficiency when compared with animals consuming the GCS and ECS starters. The SFCS starter decreased incidence of diarrhea during the postweaning period and required less veterinary treatment. These data suggest that the steam-flaking of corn and soybeans can influence the growth performance and the selected blood parameters of calves and that, in this study, the extrusion of corn and soybeans had no beneficial effect on the growth performance of calves.     

Interactions of alfalfa hay and sodium propionate on dairy calf performance and rumen development

The objective of this experiment was to investigate the effects of different levels of alfalfa hay (AH) and sodium propionate (Pro) added to starter diets of Holstein calves on growth performance, rumen fermentation characteristics, and rumen development. Forty-two male Holstein calves (40 ± 2 kg of birth weight) were used in a complete randomized design with a 3 × 2 factorial arrangement of treatments. Dietary treatments were as follows: (1) control = concentrate only; (2) Pro = concentrate with 5% sodium propionate [dry matter (DM) basis]; (3) 5% AH = concentrate + 5% alfalfa hay (DM basis); (4) 5% AH + Pro = concentrate + 5% alfalfa hay + 5% sodium propionate (DM basis); (5) 10% AH = concentrate + 10% alfalfa hay (DM basis); and (6) 10% AH + Pro = concentrate + 10% alfalfa hay + 5% sodium propionate (DM basis). All calves were housed in individual pens bedded with sawdust until 10 wk of age. They were given ad libitum access to water and starter throughout the experiment and were fed 2 L of milk twice daily. Dry matter intake was recorded daily and body weight weekly. Calves from the control, 10% AH, and 10% AH + Pro treatments were euthanized after wk 10, and rumen wall samples were collected. Feeding of forage was found to increase overall dry matter intake, average daily gain, and final weight; supplementing sodium propionate had no effect on these parameters. Calves consuming forage had lower feed efficiency than those on the Pro diet. Rumen fluid in calves consuming forage had higher pH and greater concentrations of total volatile fatty acids and molar acetate. Morphometric parameters of the rumen wall substantiated the effect of AH supplementation, as plaque formation decreased macroscopically. Overall, the interaction between forage and sodium propionate did not affect calf performance parameters measured at the end of the experiment. Furthermore, inclusion of AH in starter diets positively enhanced the growth performance of male Holstein calves and influenced both the macroscopic and microscopic appearances of the rumen wall. These benefits, however, were small when only sodium propionate was offered.     

Effects of forage source and forage particle size as a free-choice provision on growth performance,rumen fermentation,and behavior of dairy calves fed texturized starters

We investigated the interactive effects of forage source and forage particle size (PS) as a free-choice provision on growth performance, rumen fermentation, and behavior of dairy calves fed texturized starters. Forty-eight Holstein calves (42 ± 3 kg of body weight) were randomly assigned (n = 12 calves per treatment) in a 2 × 2 factorial arrangement of treatments with the factors of forage source [alfalfa hay (AH) and wheat straw (WS)] and forage PS [(AH: medium = 1.96 mm or long = 3.93 mm) and (WS: medium = 2.03 mm or long = 4.10 mm), as geometric mean diameters]. The treatments were (1) AH with medium PS (AH-MPS), (2) AH with long PS (AH-LPS), (3) WS with medium PS (WS-MPS), and (4) WS with long PS (WS-LPS). Regardless of forage PS, the preweaning starter intake, dry matter intake, metabolizable energy intake, weaning body weight, and forage intake were greater for AH calves than WS calves. Average daily gain, average daily gain/metabolizable energy intake, feed efficiency, and final body weight of the calves did not differ among groups. An interaction of forage source and forage PS influenced acetate, propionate, and acetate-to-propionate ratio in the rumen on d 35, with the greatest acetate proportion and acetate-to-propionate ratio, but the least propionate proportion for AH-MPS calves than the other calves. The total volatile fatty acid concentration and the rumen proportions of propionate (d 70), butyrate (d 35), and valerate (d 35) were greater in AH-MPS calves than in AH-LPS calves. Calves fed AH had greater total volatile fatty acid concentration (d 35 and 70) and propionate proportion (d 70), but lesser ruminal proportions of butyrate (d 35 and 70), valerate (d 35 and 70), and acetate-to-propionate ratio (d 70) compared with calves fed WS. The ruminal valerate proportion (d 70) was greatest in WS-MPS calves than the other calves. An interaction of forage source and forage PS influenced preweaning standing time and starter eating time, with the least standing time for WS-MPS calves and the greatest eating starter time for AH-LPS calves. Calves fed AH spent less time for rumination, but devoted more time to non-nutritive oral behaviors than WS calves. Calves fed forage with long PS spent more time for rumination, eating forage, and spent less time lying and non-nutritive oral behaviors than medium PS. In conclusion, forage source and PS interacted, affecting behavior and rumen fermentation when calves were fed texturized starters. In addition, a desirable ruminal pH in dairy calves can be obtained with texturized starters.     

Dietary fiber and early weaning on growth and rumen development of calves

Holstein calves were assigned to treatments of 1) pelleted prestarter (22% protein and 12% fat) and starter containing 10% alfalfa; 2) prestarter and starter containing 20% alfalfa; 3) no prestarter and starter containing 10% alfalfa; and 4) no prestarter and starter containing 20% alfalfa. Calves assigned to treatments 1 and 2 were fed 3.64 kg milk/d for 2 wk and calves assigned to treatments 3 and 4 were fed 3.64 kg milk/d for 3 wk and 1.82 kg milk/d for wk 4. Calves on treatments 2 and 3 were heavier at 10 wk but body weights and heights were similar by 6 mo. Rumen fluid and plasma measures were similar among treatments. Bull calves were assigned to treatments 1 and 3 and necropsied at 3 or 6 wk. Dry feed intakes to 3 wk and volatile fatty acid concentrations were greater for calves on treatment 1 than those on treatment 3. Wet weights of the empty reticulorumens were greater for calves on treatment 1 than those on treatment 3. Papillary development was not affected by weaning system. Calves weaned at 17 d and fed a prestarter have earlier rumen development than calves fed no prestarter and weaned later.     

Effects of supplemental butyrate and weaning on rumen fermentation in Holstein calves

The objectives of this study were to determine the effects of the weaning transition and supplemental rumen-protected butyrate on subacute ruminal acidosis, feed intake, and growth parameters. Holstein bull calves (n = 36; age = 10.7 ± 4.1 d; ± standard deviation) were assigned to 1 of 4 treatment groups: 2 preweaning groups, animals fed milk replacer only (PRE-M) and those fed milk replacer, calf starter, and hay (PRE-S); and 2 postweaning groups, animals fed milk replacer, calf starter, and hay without supplemental rumen-protected butyrate (POST-S) or with supplemental rumen-protected butyrate at a rate of 1% wt/wt during the 2-wk weaning transition (POST-B). Milk replacer was provided at 1,200 g/d; starter, water, and hay were provided ad libitum. Weaning took place over 14 d by reducing milk replacer provision to 900 g/d in wk 7, 600 g/d in wk 8, and 0 g/d in wk 9. Rumen pH was measured continuously for 7 d during wk 6 for PRE-S and PRE-M and during wk 9 for POST-S and POST-B. After rumen pH was measured for 7 d, calves were euthanized, and rumen fluid was sampled and analyzed for volatile fatty acid (VFA) profile. Individual feed intake was recorded daily, whereas, weekly, body weights were recorded, and blood samples were collected. Compared with PRE-M, PRE-S calves tended to have a greater total VFA concentration (35.60 ± 11.4 vs. 11.90 ± 11.8 mM) but mean rumen pH was unaffected (6.25 ± 0.22 vs. 6.17 ± 0.21, respectively). Between PRE-S (wk 6) and POST-S (wk 9), calf starter intake increased (250 ± 219 vs. 2,239 ± 219 g/d), total VFA concentrations increased (35.6 ± 11.4 vs. 154.4 ± 11.8 mM), but mean rumen pH was unaffected (6.25 ± 0.22 vs. 6.40 ± 0.22, respectively). Compared with POST-S, POST-B calves had greater starter intake in wk 7, 8, and 9, but POST-B tended to have lower total VFA concentration (131.0 ± 11.8 vs. 154.4 ± 11.8 mM) and lower mean ruminal pH (5.83 ± 0.21 vs. 6.40 ± 0.22). In conclusion, the weaning transition does not appear to affect rumen pH and VFA profile, but supplementing rumen-protected butyrate during the weaning transition increased starter intake and average daily gain. Further, these data suggest that the ability of the rumen to manage rumen pH changes fundamentally postweaning. Why weaned calves with lower rumen pH can achieve higher calf starter intakes is unclear; these data suggest the effect of rumen pH on feed intake differs between calves and cows.     

Intensive liquid feeding of dairy calves with a medium crude protein milk replacer: Effects on performance,rumen, and blood parameters

The objective of this study was to evaluate the effects of different liquid-feeding systems using a medium crude protein milk replacer on performance, rumen, and blood parameters. Thirty newborn Holstein calves were blocked according to birth weight and date of birth, and randomly distributed to different liquid-feeding systems: conventional (4 L/d), intensive (8 L/d), or step-up/step-down (wk 1, 4 L/d; wk 2 to 6, 8 L/d; wk 7 and 8, 4 L/d). The commercial milk replacer (12.5% solids, 20.2% crude protein, 15.6% fat) was fed twice daily (0700 and 1700 h) until calves were weaned, at 8 wk of age. Calves were individually housed in wood hutches, with free access to water and starter concentrate, and to hay only after weaning. They were followed through 10 wk of age. Milk replacer and starter intake were inversely affected by feeding system. After weaning, starter intake and hay intake were similar among feeding systems. Total dry matter intake was higher during the liquid-feeding period for calves on the intensive system compared to calves on the conventional system, but conventional feeding resulted in the highest dry matter intake after weaning. Feed efficiency was similar among feeding systems before and after weaning. Average body weight and daily gain were not affected by feeding system before or after weaning. During liquid feeding, diarrhea occurrence was lower for calves on the conventional system; however, when calves on the step-up/step-down system were fed lower volumes of liquid feed, diarrhea occurrence was similar to that of calves on the conventional system. Plasma concentrations of β-hydroxybutyrate were higher for calves on the conventional system, reflecting starter intake. Rumen pH, short-chain fatty acids, and N-NH₃ were not affected by feeding system. Feeding higher volumes of milk replacer with a medium crude protein content had no beneficial effect on the performance of calves up to 10 wk of age.     

Effects of supplemental yeast (Saccharomyces cerevisiae) culture on rumen development, growth characteristics, and blood parameters in neonatal dairy calves

Yeast (Saccharomyces cerevisiae) culture was added to a texturized calf starter at 0 (control), 1, or 2% of dry matter to determine effects on intake, growth, blood parameters, and rumen development. Seventy-five Holstein calves (38 male; 37 female) were started on the experiment at 2 +/- 1 d of age and were studied for 42 d. Starter intake was measured, and fecal scoring was conducted daily. Growth and blood parameter measurements were recorded at weekly intervals. A subset of 6 male calves (2 per treatment) was euthanized at 5 wk of age, and rumen tissue was sampled for rumen epithelial growth measurements. An additional 6 male calves were euthanized at 6 wk of age for rumen epithelial growth measurements. Inclusion of yeast culture at 2% of the starter ration significantly increased starter and total dry matter intake, average daily gain, and daily hip width change when compared with the control treatment. Average daily gain was improved by 15.6% for the 2% yeast treatment. Daily change in hip height was also significantly greater for calves receiving 2% supplemental yeast culture than for calves receiving 1%. No significant treatment differences were observed for any other variables. These data suggest that the addition of yeast culture in a dairy calf starter at 2% enhances dry matter intake and growth and slightly improves rumen development in dairy calves.     

Hay intake improves performance and rumen development of calves fed higher quantities of milk

Research to date has suggested that access to forage before weaning can limit rumen development in calves, but no research has yet addressed the role of forage for calves fed higher quantities of milk. This study compared performance and rumen development of calves provided high volumes (equivalent to approximately 20% of calf birth weight) of milk with and without access to hay. At d 3 of age, individually housed calves were randomly assigned to treatment (either ad libitum access to chopped grass hay or no forage; n = 15 calves per treatment, 10 heifers, and 5 bulls). All calves were provided ad libitum access to water and starter throughout the study. All calves were offered 8 L of milk/d from a nipple bottle from d 3 to 35, 4 L/d from d 36 to 53, and 2 L/d until weaning at d 56. Solid feed intake and growth parameters were monitored from d 3 to 70. At d 70, males from both treatments were slaughtered to measure rumen development parameters. Overall dry matter (DM) intake from solid feed did not differ between treatments before wk 5. However, during wk 6 to 10, calves fed forage consumed more total DM (starter plus hay) than did calves fed no forage. Hip and wither height, heart girth, and body barrel at d 3, 56, and 70 did not differ between treatments. Reticulorumen weight was heavier in calves fed hay versus those fed only starter (12.77 ± 1.29 vs. 7.99 ± 0.69 kg with digesta; 1.89 ± 0.05 vs.1.60 ± 0.09 kg without digesta). Body weight without digesta was similar in calves fed forage or no forage. Mean rumen pH was higher in calves fed hay compared with those fed no forage (5.49 ± 0.08 vs. 5.06 ± 0.04). In conclusion, provision of chopped hay to calves fed high volumes of milk can promote solid feed DM intake and rumen development without affecting BW gain.     

Growth performance,nutrient digestibility,and ruminal fermentation of dairy calves fed starter diets with alfalfa hay versus corn silage as forage and soybean oil versus palm fatty acids as fat source

The present study was intended to evaluate the effect of forage source (alfalfa hay; ALF vs. corn silage; CS) along with a supplemental fat source (soybean oil; SO vs. rumen-inert palm fatty acids; PF) on growth performance, nutrient digestibility, and ruminal fermentation in dairy calves. Forty-eight new-born Holstein female calves (3 d old) were assigned to one of 4 treatments: (1) alfalfa hay with soybean oil (ALF–SO); (2) alfalfa hay with palm fatty acids (ALF–PF); (3) corn silage with soybean oil (CS–SO); (4) corn silage with palm fatty acids (CS–PF). Starter diets had equal amounts of forage (100 g/kg dry matter; DM) and fat source (30 g/kg DM). Calves were fed a constant amount of milk (d 1 to 63) and had ad libitum access to water and starters (d 1 to 83). The lowest and greatest starter intakes during the preweaning period occurred in ALF–SO and CS–PF, respectively. This coincided with forage × fat source interaction for average daily gain (ADG) during preweaning. The forage source affected total DM intake and ADG over the entire period, body weight (BW) at weaning, and final BW with greater values in calves that received CS compared with ALF. The concentrations of total short-chain fatty acids and butyrate were increased, whereas concentration of acetate and acetate:propionate ratio were decreased in the rumen of calves fed CS compared with ALF. Feeding CS increased urinary excretion of allantoin and, as a trend, total purine derivatives (PD) and estimated microbial protein synthesis in comparison with ALF. The fat source affected starter intake, ADG, and BW postweaning with the highest values in PF. The digestibility of neutral detergent fiber, crude protein and, as a trend, organic matter were higher in calves fed PF compared with SO. Calves fed PF had lower ruminal ammonia-N concentration and urinary N excretion and greater urinary excretion of allantoin and total PD. Calves receiving SO had a lower ruminal protozoa population. In conclusion, supplementing starter diets with CS and PF is superior to ALF and SO. Interaction of the positive effects of CS and PF on performance underlines that concurrent supplementation of CS with PF is especially recommendable in young calves before weaning.     

Starch source evaluation in calf starter: II. Ruminal parameters, rumen development, nutrient digestibilities, and nitrogen utilization in Holstein calves

Ruminal parameters, rumen development, nutrient digestibilities, and N utilization were estimated in Holstein calves fed starch from different sources. Ground corn, ground barley, ground wheat, and crimped oats were used to formulate 4 isostarch (25% of starter dry matter) pelleted diets. These diets were randomly allocated to calves (16 calves per treatment, 8 female and 8 male) and fed ad libitum along with mixed grass hay throughout the experiment. Ruminal contents and blood were sampled at d 35, 50, and 70 of age to estimate ruminal parameters and plasma β-hydroxybutyrate, respectively. At d 70, twenty-four male calves (6/treatment) were randomly selected, euthanized, and forestomach weight, papillae length (PL), papillae width (PW), rumen wall thickness (RWT), and papillae concentration were measured. At d 63, twenty-four female calves (6/treatment) were randomly selected and moved to metabolism stalls to estimate total tract apparent nutrient digestibilities and N utilization. Female calves were given 2 wk for adaptation to experimental facilities and then total collections of feces and urine were made from d 77 to 84 of age. Ruminal pH at d 35 of age was higher in calves fed corn and oat diets than in those fed barley and wheat diets. Ruminal pH at d 50 and 70 of age was the lowest in calves on barley diets followed by those on oat and wheat diets and then by those on the corn diet. Ruminal total volatile fatty acid concentrations at d 35 of age were greatest in calves fed corn or wheat diets followed by those fed barley and oat diets. Calves on corn and wheat diets maintained greater ruminal volatile fatty acids concentrations at d 50 and 70 of age. Ruminal ammonia, acetate, propionate, butyrate, and blood β-hydroxybutyrate concentrations were also greater in calves on the corn and wheat diets. Full and empty weights of forestomach, PL, PW, RWT, and papillae concentrations were greater in calves on corn and wheat diets. Daily average intake of nutrients (dry matter, crude protein, neutral detergent fiber, starch, Ca, and P) was greater in calves fed corn and wheat diets than in those fed barley and oat diets. Starch source did not influence the total tract apparent digestibilities of nutrients in calves. Daily N retention (g/d) was greatest on the corn diet followed by the wheat diet and then the barley and oat diets. In conclusion, calves on a corn diet have greater ruminal capacity to accommodate feed bulk. More physically and metabolically functional rumens in calves on corn and wheat diets probably resulted in greater feed consumption and N retention.     

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.     

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.     

Effects of different physical forms of wheat grain in corn-based starter on performance of young Holstein dairy calves

The objective of the present study was to examine the effects of partially replacing corn with 2 forms of wheat grain on daily intake of starter feed, average daily gain, feed efficiency, rumen pH, fecal score, weaning weight, skeletal growth, and blood metabolites of dairy calves. Thirty-two male and female Holstein dairy calves (n = 8 calves per treatment) were used in a completely randomized block design. At d 3 of age, individually housed calves were randomly allocated to different treatments consisting of a starter diet with 60% ground corn (control), a starter diet with 60% whole corn, a starter diet with 30% ground corn plus 30% ground wheat (GCGW), and a starter with 30% ground corn plus 30% whole wheat (GCWW), with all other components in a meal form. All calves had free access to water and feed throughout the study period and received 4 L of milk replacer/d from d 3 to 50 and 2 L/d from d 50 to 52; weaning occurred at the end of d 52. Feed intake was recorded daily and body weight and skeletal growth measures were recorded on d 10 and every 10 d thereafter. Rumen pH was measured on d 30, 45, and 60. Blood sample were collected on d 30 and every 10 d thereafter through d 70. Data were analyzed using MIXED procedures of SAS (SAS Institute Inc., Cary, NC). Over the experimental period (d 1–70), the starter intake for the GCWW group was significantly different from the control group, but not different from the other groups. Calves fed whole wheat had a significantly greater average daily gain compared with other groups over the experimental period (d 1–70). Feed efficiency was only better in calves fed the GCWW diet than the GCGW group for postweaning and overall periods. No differences were observed for preweaning in body length, hip height, or withers height among the treatments; however, differences were significant in heart girth and body barrel. Postweaning, some of the body measurements were greater in calves fed the GCWW and GCGW starter diets. Blood glucose concentration reduced with age; however, blood urea nitrogen, β-hydroxybutyrate, albumin, and total protein increased with age. Treatment × time effects on blood urea nitrogen and total protein concentrations were detected. Blood urea nitrogen concentration (mg/dL) was affected by dietary treatments on d 30, 40, and 70, but no significant difference was detected on d 50 and 60. Serum total protein concentration (g/dL) was also affected by dietary treatments on d 40 and 70, but no significant difference was detected on d 40, 50, and 60. Whereas rumen pH was significantly reduced for the control compared with the GCWW treatment on d 45, comparison of the fecal scores showed no detectable differences among the treatments. Overall, the results of the current study indicate that starter diets containing whole wheat and ground corn can improve performance in young dairy calves compared with diets containing ground corn/ground wheat, whole corn, or ground corn, under our experimental conditions.     

Performance,nutritional behavior,and metabolic responses of calves supplemented with forage depend on starch fermentability

This study evaluated the interactive effects of forage provision on performance, nutritional behavior, apparent digestibility, rumen fermentation, and blood metabolites of dairy calves when corn grains with different fermentability were used. Sixty 3-d-old Holstein calves were randomly assigned to 1 of 4 treatments in a 2 × 2 factorial arrangement. Dietary treatments were (1) steam-flaked (SF) corn without alfalfa hay (AH) supplementation (SF-NO), (2) SF corn with AH supplementation (SF-AH), (3) cracked (CR) corn without AH supplementation (CR-NO), and (4) CR corn with AH supplementation (CR-AH). All calves received the same amount of pasteurized whole milk and weaned on d 56 of the experiment; the study was terminated on d 70. Steam-flaked corn contained higher amounts of gelatinized starch in comparison with cracked corn (44.1 vs. 12.5% of total starch, respectively). Starter intake was not affected by corn processing methods or AH provision during the pre- or postweaning periods. However, we noted an interaction between corn processing methods and forage supplementation for starter intake during d 31 to 50 of the experiment, where calves fed on SF-AH starter had greater starter intake than those fed SF-NO starter, but the starter intake was not different between CR-NO and CR-AH fed calves. Furthermore, AH increased average daily gain (ADG) of calves fed an SF-based diet but not in calves fed a CR-based diet during the preweaning and overall periods. Interaction between forage provision and time was significant for ADG and feed efficiency, as calves supplemented with forage had higher ADG (0.982 vs. 0.592, respectively) and feed efficiency compared with forage unsupplemented calves at the weaning week. Forage supplementation resulted in more stable ruminal condition compared with nonforage-fed calves, as evidenced by higher ruminal pH (5.71 vs. 5.29, respectively) at postweaning and lower non-nutritive oral behavior around weaning time (55 vs. 70.5 min, respectively). The concentration of blood β-hydroxybutyrate was also greater in calves supplemented with forage than in unsupplemented calves. Results of the present study indicated that performance response and skeletal growth were the same between 2 corn processing methods. Forage provision improved ADG of calves fed the SF-based diet, but not the CR-based diet throughout the study.     

Effects of feeding different carbohydrate sources and amounts to young calves

Corn, oats, molasses, and soyhulls are commonly used carbohydrate sources in calf starters. A total of 180 calves were used in 4 studies to compare the use of these ingredients in calf starters. Study 1 compared textured starters with different amounts of molasses or sucrose. The control starter contained 5% molasses (A). The test starters contained greater concentrations of dietary sugar than starter A as either 10% molasses (B) or 5% molasses plus 1.5% granular sucrose (C). Starters B and C were equal in dietary sugar. Study 2 evaluated textured starters containing 0 or 25% whole oats for calves up to approximately 12 wk old. Study 3 evaluated pelleted starters containing 0 or 62.75% soyhulls for calves up to approximately 8 wk old. Study 4 evaluated textured starters containing 0, 14, 28, and 42% soyhulls for calves between approximately 8 and 12 wk old. Calves were housed in individual pens in an unheated nursery with curtain sides through 8 wk and then in group pens of 6 calves/pen from 8 to 12 wk. Calves were bedded with straw. In study 1, calves fed the starters with extra molasses or sucrose had an average of 9% slower average daily gain (ADG) and greater average fecal scores from 42 to 56 d and 9% slower ADG from 0 to 56 d than calves fed the textured starter with low molasses. In study 2, ADG and feed efficiency (kg of feed/kg of gain) were 22 and 20% less, respectively, in calves fed the starter without oats from 0 to 28 d, but there were no differences thereafter. In study 3, calves fed starters with soyhulls had a 10% slower ADG and 8% lower efficiency of gain from 28 to 56 d than calves fed the starters without soyhulls. In study 4, ADG declined linearly as soyhulls increased in the starter. The change in ADG was 14% from 0 to 42% soyhulls. Replacing corn in a starter with molasses, sucrose, or soyhulls reduced postweaning ADG and increased the cost of ADG. Whole oats were an acceptable substitute for corn.     

Short communication: Effect of calf starter on rumen pH of Holstein dairy calves at weaning

The objective of this study was to evaluate the effect of feeding calf starter on rumen pH of dairy calves during weaning transition. Twenty Holstein bull calves were paired into 10 blocks by starting date of the study and body weight, and fed either milk replacer and hay (MR) or MR, hay, and a commercial texturized calf starter (MR+S) in a randomized complete block design. All calves were fed 750 g/d of milk replacer as the basal diet. Calves on MR+S treatment were also fed a calf starter ad libitum to maintain similar energy intake between calves within blocks, and MR calves were fed additional milk replacer that was equivalent to energy from calf starter intake. When MR+S calves consumed a calf starter at 680 g/d for 3 consecutive d, rumen pH of a MR+S calf and his MR counterpart was measured continuously for 3 d using a small ruminant rumen pH measurement system. Treatment did not affect minimum pH, mean pH, maximum pH, standard deviation of mean pH, and duration or area under pH 5.8, indicating that calf starter consumption did not appear to affect rumen pH. However, hay intake was negatively correlated to area under pH 5.8, with a breakpoint at 0.080 kg/d intake, suggesting hay intake might play an important role in mitigating ruminal acidosis in dairy calves during weaning transition.     

Effects of lasalocid on selected ruminal and blood metabolites in young calves.

Twelve Holstein bull calves were ruminally cannulated at 5 d of age and assigned to 0 or 1 mg of lasalocid/kg of BW daily, administered postruminally via milk replacer or into the ruminal cannula. Calves were fed milk replacer for 8 wk and calf starter for 12 wk. Lasalocid administration was terminated at weaning in calves fed lasalocid in milk replacer. Ruminal pH tended to be higher in calves fed lasalocid ruminally than in calves on control treatment and averaged 5.9 and 5.6 and 5.4 and 5.1 during wk 1 to 8 and 9 to 12, respectively. Molar proportion of ruminal butyrate tended to be lower when lasalocid was added to the rumen, particularly after weaning. Blood beta-hydroxybutyrate and acetoacetate were lower when lasalocid was administered into the rumen after weaning and averaged .897 and .646 and .026 and .015 mM in calves on control and ruminal treatments, respectively. No effects of lasalocid administered via the milk replacer were observed, except for plasma NEFA, which were reduced postweaning. These data suggest that lasalocid reduces blood beta-hydroxybutyrate by changes in ruminal fermentation and subsequent metabolism of butyrate by ruminal epithelium.