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.     

Interaction between the physical forms of starter and forage source on growth performance and blood metabolites of Holstein dairy calves

The objective of this study was to investigate the effects of the physical forms of starter and forage sources on feed intake, growth performance, rumen pH, and blood metabolites of dairy calves. Forty male Holstein calves (41.3 ± 3.5 kg of body weight) were used (n = 10 calves per treatment) in a 2 × 2 factorial arrangement of treatments with the factors being physical forms of starter (coarse mash and texturized) and forage source [alfalfa hay (AH) and wheat straw (WS)]. Individually housed calves were randomly assigned to 1 of the 4 dietary treatments, including (1) coarsely mashed (CM; coarse ground grains combined with a mash supplement) starter feed with AH (CM-AH), (2) coarsely mashed starter feed with WS (CM-WS), (3) texturized feed starter (TF; includes steam-flaked corn, steam-rolled barley combined with a pelleted supplement) with AH (TF-AH), and (4) TF with WS (TF-WS). Both starters had the same ingredients and nutrient compositions but differed in their physical forms. Calves were weaned on d 56 and remained in the study until d 70. All calves had free access to drinking water and the starter feeding at all times. No interaction was detected between the physical forms of starter feeds and forage source concerning starter intake, dry matter intake, metabolizable energy (ME) intake, average daily gain (ADG)/ME intake, ADG, and feed efficiency (FE). The preweaning and overall starter feed intake, dry matter intake, and ME intake were greater for calves fed TF starter diets than those fed CM starter diets. The ADG/ME intake was greater for calves fed TF starter diets than that fed CM starter. The FE was greater for calves fed TF starter diets compared with those fed CM starter during the preweaning, postweaning, and overall periods. The WS improved FE during the postweaning period compared with AH. The physical form of starter, forage source, and their interaction did not affect plasma glucose, triglycerides, and very low-density lipoprotein concentrations. Ruminal pH was greater for calves fed TF starter diets than those fed CM starter on d 30 of life. An interaction was observed between the physical forms of starter diets and forage source for β-hydroxybutyrate on d 28. These results showed that when starter diets contained similar ingredients and nutrient contents, processing calf starters to reduce the number of fine particles can improve the growth performance in dairy calves. Furthermore, the provision of WS improved FE and ADG of calves during the postweaning period.     

Effect of different forage sources on performance and feeding behavior of Holstein calves

One hundred seventy-nine Holstein male calves [44.7 kg of body weight (BW) and 8.3 d of age] participated in a series of 3 experiments to evaluate the effect of different forage sources on performance, apparent digestibility, and feeding behavior. Animals in each study were randomly assigned to 1 of 3 different dietary treatments: control (CON) calves were fed starter feed without any forage provision (this treatment was repeated in each of the 3 experiments), and the 2 other treatments consisted of the same starter feed plus a forage source: chopped alfalfa (AH) or rye-grass hay (RH) in the first study; chopped oat hay (OH) or chopped barley straw (BS) in the second study; corn silage (CS) or triticale silage (TS) in the third study. All calves were offered 2L of milk replacer (MR) at 12.5% dry matter (DM) twice daily via a bottle until 50 d of age, and 2L of MR at 12.5% DM during the week before weaning (57 d of age). The study finished when calves were 71 d old. Starter feed, MR, and forage intakes were recorded daily and BW weekly. Calves were individually housed and bedded with wood shavings. Compared with CON, animals receiving OH, TS, and BS consumed more starter feed (0.88 vs. 1.14, 1.17, 1.06 kg/d, respectively) and had greater average daily gain (0.72 vs. 0.93, 0.88, 0.88 kg/d, respectively). Animals in treatments RH, BS, CS, and TS consumed less forage (51 g/d) than AH (120 g/d) and OH (101 g/d) calves. Apparent organic matter, DM, and neutral detergent fiber digestibilities did not differ among treatments (81.5, 81.1, and 54.4%, respectively). Apparent crude protein digestibility was greater in RH, CS, and AH treatments than in CON (80.5 vs. 76.4%, respectively). Compared with CON calves, animals in the AH treatment spent less time eating starter feed and lying, animals in AH and RH treatments spent more time ruminating, with odds ratios (OR) of 5.24 and 5.40, respectively. The AH and RH calves devoted less time to performing nonnutritive oral behaviors (OR: 0.38 and 0.34, respectively), and TS calves tended to devote less time to perform nonnutritive oral behaviors (OR: 0.21) 1h after being offered MR and solid feed. In conclusion, free-choice provision of a forage source to young calves improves feed intake and performance without impairing digestibilities of DM, organic matter, crude protein, and neutral detergent fiber, and, depending on forage source, reduces nonnutritive oral behaviors and stimulates rumination.     

Effects of forage provision to dairy calves on growth performance and rumen fermentation: A meta-analysis and meta-regression

A meta-analysis of the potential effect of forage provision on growth performance and rumen fermentation of dairy calves was conducted using published data from the literature (1998–2016). Meta-regression was used to evaluate the effects of different forage levels, forage sources, forage offering methods, physical forms of starter, and grain sources on the heterogeneity of the results. We considered 27 studies that reported the effects of forage provision to dairy calves. Estimated effect sizes of forage were calculated on starter feed intake, average daily gain (ADG), feed efficiency (FE), body weight (BW), and rumen fermentation parameters. Intake of starter feed, ADG, BW, ruminal pH, and rumen molar proportion of acetate increased when supplementing forage but FE decreased. Heterogeneity (the amount of variation among studies) was significant for intake of starter feed, ADG, FE, final BW, and rumen fermentation parameters. Improving overall starter feed intake was greater in calves offered alfalfa hay compared with those offered other types of forages. During the milk feeding and overall periods, improving ADG was greater for calves fed a high level of forage (>10% in dry matter) compared with those fed a low level of forage (≤10% in dry matter) diets. The advantages reported in weight gain at a high level of forage could be due to increased gut fill. Improving overall ADG was lower for calves offered forages with textured starter feed compared with ground starter feed. The meta-regression analysis revealed that changes associated with forage provision affect FE differently for various forage sources and forage offering methods during the milk-feeding period. Forage sources also modulated the effect of feeding forage on ruminal pH during the milk-feeding period. In conclusion, forage has the potential to affect starter feed intake and performance of dairy calves, but its effects depend on source, level, and method of forage feeding and physical form of starter feed independently of grain sources included in the starter feed.     

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.     

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: I. Feed consumption, body weight gain, structural growth, and blood metabolites in Holstein calves

Holstein calves were fed pelleted iso-starch (25% of starter dry matter) diets containing barley (n = 16), corn (n = 16), oat (n = 16), and wheat (n = 16) starch for 12 wk of age. Feed consumption, nutrient intake, body weight (BW) gain, skeletal growth, and selected blood metabolites in calves during preweaning (d 1 to 49) and postweaning (d 50 to 84) periods were measured. Average daily starter consumption during pre-weaning and postweaning periods was the greatest in calves fed corn died followed by those fed a wheat diet and then in those fed barley and oat diets. During the preweaning period, the calves provided corn and wheat diets consumed greater amount of mixed grass hay than those fed barley and oat diets. During the postweaning period, mixed grass hay intake was the greatest in calves provided corn diet followed by those fed a wheat diet and then in those fed barley and oat diets. Nutrients (dry matter, crude protein, starch, and neutral detergent fiber) intake followed the solid feed consumption pattern in calves. Body weight and body measurements (body length, body barrel, heart girth, wither height, and hip height) at birth and at weaning (d 49) in calves fed different starch sources were similar. Body weight and body measurements at postweaning (d 84) were the greatest in calves fed a corn diet followed by those fed a wheat diet and then in those fed barley and oat diets. Overall average BW gain and total dry matter intake were the greatest in calves fed a corn diet than in those fed wheat, barley, and oat diets. Feed efficiency was greater in calves fed corn and wheat diets than in those fed barley and oat diets. Blood glucose, blood urea N, triglycerides, cholesterol, and creatinine were reduced with the advancing age of calves. Lesser blood glucose and greater blood urea N concentrations at wk 8, 10, and 12 of age were noticed in calves fed corn diet than in those fed barley, oat, and wheat diets. Occurrence of diarrhea was more frequent in calves fed oat diet than in those provided barley, corn, and wheat diets. Starch sources did not influence respiratory score, rectal temperature, and general appearance score. In conclusion, the calves on corn diet consumed more solid feed and gained greater BW than those fed barley, oat, and wheat diets.     

Corn silage versus corn silage:alfalfa hay mixtures for dairy cows: effects of dietary potassium, calcium, and cation-anion difference

Corn silage (CS) has replaced alfalfa hay (AH) and haylage as the major forage fed to lactating dairy cows, yet many dairy producers believe that inclusion of small amounts of alfalfa hay or haylage improves feed intake and milk production. Alfalfa contains greater concentrations of K and Ca than corn silage and has an inherently higher dietary cation-anion difference (DCAD). Supplemental dietary buffers such as NaHCO₃ and K₂CO₃ increase DCAD and summaries of studies with these buffers showed improved performance in CS-based diets but not in AH-based diets. We speculated that improvements in performance with AH addition to CS-based diets could be due to differences in mineral and DCAD concentrations between the 2 forages. The objective of this experiment was to test the effects of forage (CS vs. AH) and mineral supplementation on production responses using 45 lactating Holstein cows during the first 20 wk postpartum. Dietary treatments included (1) 50:50 mixture of AH and CS as the forage (AHCS); (2) CS as the sole forage; and (3) CS fortified with mineral supplements (CaCO₃ and K₂CO₃) to match the Ca and K content of the AHCS diet (CS-DCAD). Feed intake and milk production were equivalent or greater for cows fed the CS and CS-DCAD diets compared with those fed the AHCS diet. Fat percentage was greater in cows fed the CS compared with the AHCS diet. Fat-corrected milk (FCM; 3.5%) tended to be greater in cows fed the CS and CS-DCAD diets compared with the AHCS diet. Feed efficiencies measured as FCM/dry matter intake were 1.76, 1.80, and 1.94 for the AHCS, CS, and CS-DCAD diets, respectively. The combined effects of reduced feed intake and increased FCM contributed to increased feed efficiency with the CS-DCAD diet, which contained 1.41% K compared with 1.18% K in the CS diet, and we speculate that this might be the result of added dietary K and DCAD effects on digestive efficiency. These results indicate no advantage to including AH in CS-based diets, but suggest that improving mineral supplementation in CS-based diets may increase feed efficiency.     

Reconstituted versus dry alfalfa hay in starter feed diets of Holstein dairy calves: Effects on feed intake,feeding and chewing behavior,feed preference,and health criteria

We investigated the effect of reconstitution of alfalfa hay on feeding and chewing behavior, sorting activity, and health status using 20 neonate Holstein male calves (3 d of age; 40.3 ± 1.30 kg of body weight) that were assigned randomly to 2 treatments, a starter feed containing either 10% dry (AH) or reconstituted alfalfa hay (RAH), each consisting of 10 calves. Alfalfa hay was reconstituted with water 24 h before feeding to achieve a theoretical dry mater (DM) content of 20%. Both starter diets had the same ingredients and nutrient compositions but differed in their DM content (90.9 vs. 66.6% DM for AH vs. RAH, respectively). Calves were weaned on d 50 and remained in the study until d 70. Reconstitution of alfalfa hay increased the percentage of particles retained on 8- and 1.18-mm sieves, but reduced feed materials retained on the bottom pan. Feeding RAH tended to increase meal frequency (preweaning) and increased meal duration (pre- and postweaning), and thereby increased time devoted to eating without affecting nutrient intake. Calves fed RAH tended to have lower eating rate during the pre- and postweaning periods. Tendencies to concurrent increase in rumination frequency and rumination duration in calves fed RAH increased time devoted to ruminating during the preweaning period; however, a tendency to longer rumination duration did not affect ruminating time during the postweaning period. Calves fed RAH spent less time resting and standing and more time drinking during the postweaning period. Non-nutritive oral behaviors were not affected by treatment during the pre- and postweaning period. Feeding RAH decreased sorting of particles retained on 8-mm sieve compared with AH; however, calves in both treatment groups sorted for particles retained on 8- and 1.18-mm sieves and against the feed materials retained on the bottom pan. Crude protein and neutral detergent fiber intakes of particles retained on the both 8- and 1.18-mm sieves increased in calves fed RAH versus AH, with no changes in intake of nutrients retained on the bottom pan. Calves fed AH were more susceptible to develop diarrhea (odds ratio = 2.02) and pneumonia (odds ratio = 4.74) and thereby had lower chances of being treated. We found no difference between treatment groups for frequency and medication days of diarrhea; however, calves fed RAH experienced fewer days with diarrhea. Furthermore, frequency and number of days with pneumonia and administration of medication were greater for calves fed AH compared with calves fed RAH. Blood concentrations of total protein and globulin tended to be higher in calves fed RAH compared with calves fed AH. Overall, feeding RAH increased time devoted to eating by increasing meal frequency and meal duration but did not affect feed intake due to lower eating rate. Calves in both treatment groups exhibited feed sorting at the extent to which they balanced intake of nutrients and met their nutritional needs. Calves, in general, were healthy, but it seems that feeding a diet containing reconstituted alfalfa hay has a potential health-promoting effect, possibly through reducing diet dustiness and improving immune status.     

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 starter protein content and alkali processing of wheat straw on growth,ruminal fermentation,and behavior in Holstein calves

The present study was conducted to investigate the effects of crude protein (CP) content of starter feed and wheat straw (WS) processing on growth performance, digestibility, ruminal fermentation, and behavior of Holstein calves. Sixty calves (28 male and 32 female) were randomly assigned to 1 of 4 treatments in a randomized complete block design. Treatments in a 2 × 2 factorial arrangement were (1) lower-CP ground starter feed mixed with alkali-processed WS (LP-PWS), (2) lower-CP ground starter feed mixed with unprocessed WS (LP-WS), (3) higher-CP ground starter feed mixed with alkali-processed WS (HP-PWS), and (4) higher-CP ground starter feed mixed with unprocessed WS (HP-WS). Wheat straw was fed at 4.75% of dry matter (DM), and low-protein (LP) and high-protein (HP) starter feed contained 19.5 and 23.5% CP, respectively. The calves were weaned on d 60 and remained in the study until d 75. During the experiment, the calves received 4.2 kg of whole milk per day and had free access to fresh water and starter feed. The interaction between WS processing and protein content of starter tended to be significant for starter feed intake, average daily gain (ADG), and body weight (BW); calves fed HP-PWS tended to have greater ADG and final BW than other treatments. The results showed that feeding HP ground starter feed increased ADG and feed efficiency compared with LP groups during the preweaning and the overall periods. Moreover, weaning and final BW were higher in HP-fed calves than in LP-fed calves. Apparent digestibilities of acid detergent fiber (ADF), starch, and CP were greater in calves fed HP than in calves fed LP starter feed. The HP ground starter feed increased rumen propionate and ammonia concentrations. Wheat straw processing had no effect on intake and growth of calves but increased DM, ADF, and neutral detergent fiber digestibilities and decreased ruminal pH. Using processed wheat straw (PWS) mixed with starter feed tended to decrease rumination time and ruminal acetate concentration in calves. Final body barrel and withers height tended to be greater in calves fed PWS. Overall, the results indicated that HP content of ground starter feed (23.5%) could be recommended for Holstein calves. Furthermore, PWS inclusion in the ground starter diet increased fiber digestibility but had no effect on calf performance. Moreover, calves fed HP-PWS had greater ADG and final BW than other treatments.     

Whole-plant flint corn silage inclusion in total mixed rations for pre- and postweaning dairy calves

Assuming that acetic acid plays a minor role in the development of ruminal epithelium of preweaning dairy calves, the fiber supply for growing calves has been neglected. More research has been done on including starch and nonfibrous carbohydrates in solid feed for preweaning calves. Accordingly, the fiber requirement of these calves is not well known, as diet recommendations vary greatly. Hence, elucidating the effects of including fiber from long particle sizes in the diet may be essential for helping calves overcome the transition challenge during weaning. Forty-five Holstein calves were used in a randomized block design, considering sex, birth date, and weight at 28 d of age, when the supply of the total mixed ration (TMR) with the inclusion of corn silage started. Three TMR with increasing whole-plant flint corn silage content (0, 10, or 20% on a dry matter basis) were compared: 0CS, 10CS, or 20CS, respectively. During the first 28 d of life, the calves were managed homogeneously and were fed 6 L/d of whole milk, a commercial calf starter pelleted, and water ad libitum. Next, the solid diet was changed to the respective solid feed treatment. Calves were gradually weaned from 52 to 56 d of age but were evaluated for an additional 14 d postweaning. Feed intake was measured daily, while body weight and metabolic indicators of intermediate metabolism were evaluated weekly. Ruminal fluid was collected at 6, 8, and 10 wk of age. Behavioral analysis was conducted on wk 7 (preweaning) and 10 (postweaning). There was a quadratic effect for dry matter intake from wk 7 to 10, with higher intake for the 10CS diet than the 0CS and 20CS diets. Consequently, the 10CS diet also promoted greater average daily gain at wk 8 and 9 compared with the 0CS and 20CS diets. However, the final body weight was not affected by the different solid diets. Silage inclusion in calves' diet positively affected time spent ruminating and chewing pre- and postweaning. Including 10% of whole-plant flint corn silage in the diets of young dairy calves is a strategy to increase total solid intake and decrease acidosis risk by increasing pH and ruminating activity around weaning.     

Substituting corn silage with reconstituted forage or nonforage fiber sources in the starter feed diets of Holstein calves: Effects on intake,meal pattern,sorting, and health

We examined the effect of replacing corn silage (CS) with reconstituted alfalfa hay (RAH) or reconstituted beet pulp (RBP) in the starter diets on feeding behavior, sorting, and health criteria using 54 neonatal female Holstein calves that were assigned randomly to 3 groups receiving starter diets containing CS (10% on a dry matter basis), RAH, or RBP. The starter diets had the same nutrient composition and moisture level but differed in particle size distribution. Calves fed CS tended to have a lower intermeal interval compared with calves fed RAH before weaning; however, meal frequency and duration, eating rate, and meal size were not affected by treatment before and after weaning, which resulted in no changes in feed intake and time spent eating. Rumination frequency was higher for calves fed CS than for calves fed RAH or RBP after weaning. Feeding RBP decreased rumination duration compared with CS and RAH after weaning; however, calves fed RBP had a higher rumination bout interval compared with calves fed CS. Calves fed CS spent more time ruminating compared with calves fed RAH or RBP after weaning. Feeding CS tended to decrease and decreased time devoted to standing and lying, respectively, compared with calves fed RBP; however, calves fed RBP tended to spend more time on nonnutritive oral behaviors compared with calves fed RAH. Calves fed CS sorted against particles retained on the 8-mm sieve of the Penn State Particle Separator (PSPS) and for particles retained on the 1.18-mm sieve of the PSPS. Feeding RAH increased sorting for particles retained on the 8- and 1.18-mm sieves of the PSPS. Calves fed RBP sorted only for particles retained on the 1.18-mm sieve of the PSPS. Calves fed RBP tended to be more susceptible to developing pneumonia compared with calves fed CS or RAH; however, frequency and duration of diarrhea and pneumonia or number of days needed to medicate the diseases were unchanged across treatment groups. Initial (d 3) blood total protein concentration was similar (6.51 g/dL) across treatment groups. Overall, replacing CS with RAH or RBP did not affect time devoted to eating and feed intake due to no significant changes in meal size or intermeal interval before and after weaning. Calves showed feed sorting at the extent to which they balanced intake of nutrients and met their nutritional needs. Calves in general were healthy; therefore, CS, RAH, or RBP can be used interchangeably based on availability and competitive feed price.     

Reconstituted versus dry alfalfa hay in starter feed diets of Holstein dairy calves: Effects on growth performance,nutrient digestibility,and metabolic indications of rumen development

We investigated the effect of reconstitution of alfalfa hay on starter feed intake, nutrient digestibility, growth performance, rumen fermentation, selected blood metabolites, and health criteria of dairy calves during the pre- and postweaning periods. A total of 20 newborn male Holstein calves (3 d of age; 40.3 ± 1.30 kg of body weight; ±SE) were assigned randomly to 1 of 2 treatments, a starter feed containing either 10% dry (AH) or reconstituted alfalfa hay (RAH), each consisting of 10 calves. Alfalfa hay was reconstituted with water 24 h before feeding to achieve a theoretical dry matter content of 20%. Both starter feeds had the same ingredients and nutrient compositions but differed in their dry matter content (91.2 and 83.8% dry matter for AH and RAH, respectively). Calves were weaned on d 50 and remained on the study until d 70. All calves had free access to fresh and clean drinking water and the starter feed at all times. During the study period, the average maximum temperature-humidity index was 73.8 units, indicating no degree of environmental heat load for dairy calves. Starter feed dry matter intake, total dry matter intake, and body weight (at weaning and at the end of the trial) were unaffected by treatment. Nutrient intake (except for total ether extract intake) increased during the postweaning period compared with the preweaning period. Average daily gain and feed efficiency were unchanged between treatments. Calves had higher average daily gain and skeletal growth during the postweaning period; however, feed efficiency was lower during the post- versus preweaning period. Calves fed RAH gained more hip width and body barrel compared with calves fed AH during the preweaning and all studied periods, respectively. Rectal temperature was similar between treatments, but feeding RAH decreased fecal score and general appearance score during the preweaning period. Apparent total-tract nutrient digestibility was not affected by reconstitution of alfalfa hay; however, reconstitution increased total-tract digestibility of neutral detergent fiber during the postweaning period. Ruminal fluid pH, and concentrations and profile of total volatile fatty acids were unchanged between treatments. Molar concentration of propionate and acetate to propionate ratio increased and decreased, respectively, during the postweaning period. Reconstitution of alfalfa hay did not affect concentrations of glucose, β-hydroxybutyrate, blood urea N, and albumin, and albumin to globulin ratio during the studied periods; however, reconstitution increased concentration of blood total protein during the overall period. Calves had higher concentrations of blood glucose and globulin during the preweaning and β-hydroxybutyrate during the postweaning period. Overall, reconstitution of alfalfa hay did not interact with calf phase (pre- vs. postweaning) to affect dry matter intake, growth performance, and metabolic indications of rumen development (measured as ruminal volatile fatty acids and selected blood metabolites), but improved health-related variables (fecal score and general appearance score) during the preweaning period.     

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.     

Chewing,rumen pool characteristics,and lactation performance of dairy cows fed 2 concentrations of a corn wet-milling coproduct with different forage sources

We used a novel corn wet-milling coproduct [CMP; approximately 70% dry matter, 28% crude protein, 36% neutral detergent fiber (NDF), and 18% nonstructural carbohydrates] in diets formulated to contain 18.4% forage NDF, 17.4% crude protein, 20.2% starch, and 3.7% sugar. Six primiparous, rumen-cannulated Jersey cows were assigned to a 6 × 6 Latin square design with a 2 × 3 factorial arrangement of treatments. Diets were formulated to contain 20 and 30% CMP with 3 forage sources [corn silage (CS) and 40.5% NDF, CS replaced with 10% alfalfa hay (AH) and 45.0% NDF, or CS replaced with 7% grass hay (GH) and 67.4% NDF], with each providing 18.4% forage NDF in the diet. Total-tract digestibilities of NDF, N, and organic matter were not affected by treatment. Similarly, no treatment effects were detected for kinetics of NDF disappearance in situ from CMP or respective forage source or for N disappearance in situ from CMP. Grass hay increased total and liquid pool size of rumen contents compared with AH (by 3.2 and 3.0 kg, respectively). Total time spent chewing increased in cows fed GH by over 35 min compared with those fed AH, partially due to a trend for increased minutes spent ruminating. Mean particle size of rumen contents also tended to be higher in the GH (0.55 mm) than AH (0.69 mm) diets. No effects on production of milk or milk components were detected, but dry matter intake (DMI) tended to decrease when CMP increased from 20 to 30%. Gross feed efficiency (fat-corrected milk/DMI) tended to be greater when cows were fed AH and GH compared with CS and was greater for AH than GH diets. In diets containing low starch, increasing CMP from 20 to 30% potentially maintained similar fat-corrected milk production with lower DMI. However, more consideration also should be given to interactions among forages with respect to fill, digestion, and passage of fiber with increased inclusion rates of CMP.     

Effects of forage provision to young calves on rumen fermentation and development of the gastrointestinal tract

Fifteen Holstein male calves were randomly assigned to 1 of 3 dietary treatments according to age and body weight (BW) to determine the effects of feeding different forages sources on rumen fermentation and gastrointestinal tract (GIT) development. Treatments consisted of a starter (20% crude protein, 21% neutral detergent fiber) fed alone (CON) or supplemented with alfalfa (AH) or with oat hay (OH). All calves received 2 L of milk replacer (MR) at 12.5% dry matter twice daily until 49 d of age. Calves received 2 L of the same MR from 50 to 56 d of age and were weaned at 57 d of age. Individual starter, forage, and MR intakes were recorded daily and BW was recorded weekly. A rumen sample was taken weekly to determine rumen pH and volatile fatty acid concentrations. Three weeks after weaning, animals were harvested and each anatomical part of the GIT was separated and weighed with and without contents. Rumen pH was lower in CON than in OH and AH calves. Furthermore, acetate proportion in the rumen liquid tended to be greater in AH than in CON and OH treatments. Total GIT weight, expressed as a percentage of BW, tended to be greater in AH compared with the other 2 treatments. Rumen tissue tended to weigh more in CON than in OH animals. Animals with access to forage tended to have a greater expression of monocarboxylate transporter 1 than CON calves. In conclusion, calves supplemented with oat hay have a better rumen environment than calves offered no forage and do not have an increased gut fill.     

Growth performance,feeding behavior,health status,and blood metabolites of environmentally heat-loaded Holstein dairy calves fed diets supplemented with chromium

We investigated the effect of Cr supplementation on growth performance, feeding behavior, health status, and blood metabolites of summer-exposed dairy calves during the pre- and postweaning periods. A total of 24 newborn Holstein female calves (1 d of age; 42.1 ± 0.89 kg of body weight) were assigned randomly to a control group (no Cr supplement; Cr?) or a Cr group (Cr+) receiving 0.05 mg of Cr/kg of body weight^0.75. During the study period, the average maximum temperature-humidity index was 81.3 units, indicating a high environmental heat load. Chromium was provided in colostrum and milk during the preweaning period, and in the starter feed during the postweaning period. Calves had free access to fresh water and starter feed throughout the experiment and were weaned on d 63. Starter feed intake and total dry matter intake were greater in Cr+ calves. Despite decreased meal frequency in Cr+ calves, during the preweaning period the starter feed intake increased due to increases in meal duration and meal size and a tendency for greater meal interval. Increased postweaning starter intake in Cr+ calves was attributed to a tendency for an increase in meal duration. Chromium-supplemented calves had greater overall weight gain, but their feed efficiency and rectal temperature were not affected by Cr treatment. Chromium supplementation tended to increase the heart girth during the preweaning and overall periods and increased the hip width during the postweaning and overall periods. Respiration rates were lower in Cr+ calves than Cr? calves during the preweaning and overall periods. During the preweaning period, the time spent in eating and ruminating per 12-h period was not affected by Cr treatment. During the postweaning period, the rumination time (min per 12-h period) was unaffected but total eating time (min per 12-h period) increased in Cr+ calves. Times spent resting, drinking, standing, lying, and in nonnutritive oral behaviors were not affected by treatments during the pre- and postweaning periods. Chromium supplementation had no effects on serum concentrations of cortisol, triiodothyronine, and thyroxine measured at weaning or the end of the trial. The Cr+ calves tended to have higher serum concentrations of glucose and a higher ratio of insulin to glucose measured at the end of the trial. In conclusion, Cr supplementation of both liquid and solid feeds improved growth performance in summer-exposed calves as a result of reduced respiration rate and increased feed intake; however, no beneficial effects were found on feed efficiency and insulin metabolism.     

Effects of corn processing on growth characteristics, rumen development, and rumen parameters in neonatal dairy calves

Neonatal Holstein calves were fed texturized calf starters containing 33% whole (WC), dry-rolled (DRC), roasted-rolled (RC), or steam-flaked (SFC) corn to investigate how corn processing method affects intake, growth, rumen and blood metabolites, and rumen development. In the first experiment, 92 Holstein calves (52 male and 40 female) were started at 2 +/- 1 d of age and studied for 42 d. Starter dry matter (DM) intake was measured and fecal scoring conducted daily. Growth and blood parameter measurements were conducted weekly. A subset of 12 male calves (3/treatment) was euthanized at 4 wk of age and rumen tissue sampled for rumen epithelial development measurements. Experiment 2 consisted of 12 male Holstein calves ruminally cannulated at 7 +/- 1 d of age. Rumen fluid and blood samples were collected during wk 2 to 6. In the first experiment, postweaning and overall starter and total DM intake were significantly higher in calves fed starter with DRC than RC or SFC. Postweaning and overall starter and total DM intake were significantly higher in calves fed starter with WC than SFC. Postweaning average daily gain was significantly greater in calves fed starter with DRC than SFC. Blood volatile fatty acid concentrations were significantly higher in calves fed starter with SFC than in calves fed all other treatments. Papillae length and rumen wall thickness at 4 wk were significantly greater in calves fed starter with SFC than DRC and WC, respectively. In experiment 2, calves fed starter with WC had higher rumen pH and lower rumen volatile fatty acid concentrations than calves fed all other starters. Rumen propionate production was increased in calves receiving starter with SFC; however, rumen butyrate production was higher in calves fed starter with RC. Results indicate that the type of processed corn incorporated into calf starter can influence intake, growth, and rumen parameters in neonatal calves. Calves consuming starter containing RC had similar body weight, feed efficiency, and rumen development but increased structural growth and ruminal butyrate production when compared with the other corn processing treatments.     

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

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