Effect of feed presentation on feeding patterns of dairy calves

The objectives of this study were to determine the effect of feed presentation on meal frequency and duration, as well as diurnal feeding patterns of dairy calves, and to assess any longer-term differences in feeding patterns resulting from previous experience. Twenty Holstein bull calves were exposed from wk 1 to 8 of life to 1 of 2 feed presentation treatments: concentrate and chopped grass hay (<2.5 cm) offered at a ratio of 7:3 as a mixture (MIX), or as separate components (COM). Feed was provided ad libitum. Calves received 8 L/d of milk replacer (1.2 kg of dry matter), with the amount progressively reduced after 5 wk to facilitate weaning by the end of wk 7. At the beginning of wk 9, all calves received the MIX diet and remained on trial for an additional 3 wk. Feeding behavior was recorded from video for 4 d during wk 6, 8, 9, and 11. In wk 6, calves fed MIX spent more time feeding than calves fed COM (56.7 vs. 46.8 min/d). In wk 8, calves fed MIX spent more time feeding (174.0 vs. 139.1 min/d) and had a lower rate of intake (11.5 vs. 14.7 g/min) compared with calves fed COM. Meal frequency was similar between treatments (12.2 meals/d). Diurnal feeding patterns in wk 8 were also affected by feed presentation, with calves fed MIX spending less time feeding at time of feed delivery and more time feeding throughout the rest of the daylight hours than calves fed COM. Diurnal feeding patterns of hay and concentrate in wk 8 differed for calves fed COM, with more time spent consuming hay at time of feed delivery and less time spent consuming hay throughout the rest of the day. Once calves previously fed COM were transitioned to the MIX diet in wk 9, meal frequency, meal duration, and diurnal feeding patterns were similar between treatments: both treatments spent similar amounts of time feeding (173.9 min/d) and had similar peaks in feeding activity at time of feed delivery, sunrise, and sunset. Provision of hay and concentrate to young calves as a mixed ration, compared with separate components, increases time spent feeding and results in more evenly distributed diurnal feeding patterns. However, differences in feeding patterns resulting from feed presentation did not persist after 8 wk of age, when all calves were fed a mixed ration.     

Different feed presentations affect subsequent feed sorting and rumen pH for a short period in weaned calves

The objective of this study was to investigate the short- and long-term effects of different feed presentations on feed sorting and rumen pH in weaned calves. Thirty-six weaned female calves at the age of 12 wk (78 d) were raised in pairs (18 pens; n = 6/treatment) and randomly exposed to 1 of 3 feed presentation treatments: (1) concentrate ration (CON, only exposed to concentrate); (2) separate ration (CH, exposed to concentrate and hay as separate components); and (3) mixed ration (Mix, exposed to a mixed diet containing 75% concentrate and 25% hay). After 4 wk (from d 78 to 105) on different feed presentations, all weaned calves were introduced to a novel total mixed ration (TMR) for another 12 wk (from d 106 to 189). Fresh feed and orts were sampled daily before (wk 12 to 15) and after (wk 16, 17, and 28) transitioning to a TMR diet for analysis of feed sorting. Rumen fluid was sampled in wk 12, 13, 15, 16, 17, and 28 to determine rumen pH. The performance of weaned calves was affected by the different feed presentations during the pre-changing period, such that calves fed CON had a lower dry matter intake (DMI) and average daily gain than calves fed CH and Mix diets. When calves were introduced to the Mix diet, they immediately developed a higher degree of sorting behavior against the long particle fractions. Upon transition to TMR, we did not observe any differences in the performance of calves. However, the sorting behavior established in Mix calves persisted and was similar to calves previously fed the CON diet, whereas the extent of feed sorting in calves initially fed CH was less compared with that in the other 2 treatments in wk 16 and 17. Before changing the diet was transitioned to a TMR, calves fed CON had a lower rumen pH than calves fed CH and Mix. Although rumen pH in all treatments increased to the same level after the diet changed, we observed a tendency toward lower rumen pH in calves fed Mix compared with calves fed CH at wk 17, which might have resulted from the higher degree of feed sorting in these calves. However, by the end of the experiment (wk 28), feed sorting and rumen pH were similar across all treatments. These results indicated a short-term effect of previous feed presentations on subsequent feed sorting and rumen pH, but in the long term disappeared.     

Short communication: Feeding method affects the feeding behavior of growing dairy heifers

There is limited information available on what is the most appropriate feeding method for growing dairy heifers. The objective of this study was to determine the effect of feeding method on the feeding behavior and diet selection of growing dairy heifers. Six prepubescent Holstein heifers (158.2 ± 4.0 d old, weighing 168.2 ± 15.7 kg), fed once per day for 1.0 kg/d of growth, were subjected to each of 3 treatments in 3 successive 7-d treatment periods using a replicated 3 × 3 Latin square design. Treatments consisted of feeding 2.02 kg/d dry matter of grain concentrate and ad libitum chopped grass hay as: 1) choice (grain concentrate and hay in separate feed bins), 2) top-dressed ration (grain concentrate placed on top of the hay in one feed bin), and 3) total mixed ration (TMR, grain concentrate mixed with hay in one feed bin). Dry matter intake (DMI) and feeding behavior were monitored for 7 d for each animal on each treatment, and feed sorting was monitored for the last 3 d of each treatment period. The provision of grain concentrate and hay in either a choice or top-dressed situation resulted in young dairy heifers rapidly consuming the grain concentrate portion of their ration in very few, large meals before consuming the hay portion of their ration. The provision of the 2 ration ingredients as a TMR increased the distribution of DMI over the day and reduced the amount of sorting (against long forage particles, and for short grain concentrate particles) by heifers. These results suggest that the provision of a TMR to growing dairy heifers, as opposed to feeding concentrate and hay as either a choice or top-dressed, promotes a more balanced intake of nutrients across the day.     

Effects of forage presentation and addition of molasses-based liquid feed on dairy calf dietary selection and feed sorting of mixed diets

The objective of this study was to examine the effects of including a molasses-based liquid feed on sorting of a mixed diet of starter and hay, and to compare the nutrient composition of the ration consumed by calves offered hay and starter according to different feed presentations. Holstein bull and heifer calves were exposed for the first 8 wk of life to 1 of 3 feed presentation treatments: (1) starter and hay provided in separate buckets (n = 15), (2) a mixed diet of 80% starter and 20% hay (n = 16), or (3) a mixed diet containing the same ratio of starter and hay, with inclusion of 10% (as-is basis) liquid molasses (n = 14). Calves received 8 L/d of pasteurized waste milk and were weaned over a 10-d period beginning at 42 d of age. Intake was recorded daily and calves were weighed weekly. Fresh and refused feed were sampled on 3 consecutive days during wk 4 and 6 of the preweaning period and wk 8 immediately postweaning. Sorting was assessed through nutrient analysis of the feed samples, with additional sorting indices reflective of sorting for starter and hay components calculated based on weighted averages of individual nutrient intakes as a percent of predicated intakes. Dry matter intake and average daily gain did not differ among treatments. During the preweaning period, addition of molasses to the mixed diet did not affect the extent of feed sorting, with calves provided both mixed diets sorting, on average, in favor of starter and against hay. Postweaning, addition of molasses tended to reduce the extent of feed sorting, although calves on both treatments persisted in sorting for starter and against hay. Across treatments, there was an association between the pre- and postweaning extent of feed sorting, suggesting a degree of individual consistency in sorting behavior. Calves provided starter and hay separately consumed a diet consisting of approximately 18 to 19% hay preweaning and 14% hay postweaning, and generally had greater fiber intake and lower intake of nonfiber carbohydrates compared with calves provided a mixed diet. These results indicate that addition of molasses slightly reduced sorting during the postweaning period only. On average, calves provided both mixed diets sorted their feed in favor of starter and against hay, which mirrored dietary selection exhibited by calves offered hay and starter separately.     

Effects of different feed type exposure in early life on performance,rumen fermentation,and feed preference of dairy calves

The aim of the study was to evaluate the effects of early feed exposure (EFE) to different feedstuffs in dairy calves on feed preference once fed a free-choice diet and a total mixed ration later in life. Thirty (30) female Holstein calves were randomly assigned at birth to 1 of 3 EFE treatments—concentrate only (CON), hay only (HO), and concentrate and hay (COH)—from d 2 to 56. After that, all calves were offered both concentrate and hay in different buckets from d 57 to 70 to allow them free choice between the 2 feedstuffs. Calves were then transferred to a heifer barn, housed within treatment in pairs (2 calves/pen), and fed TMR from d 71 to 196. Feed intake was recorded daily from d 2 to 70 to determine the feed preference before and after weaning. Fresh TMR and orts were collected daily in the last week of the experiment (d 190 to 196) for analysis of feed sorting and intake. Body weight and structural growth were recorded at d 1, 28, 56, 70, and 190. Blood for determining glucose and rumen fluid for determining ruminal pH and volatile fatty acids concentrations were sampled on d 28, 56, 70, and 190. Early feed exposure did not affect feed intake, body weight, average daily gain, blood glucose, and structural growth before and after weaning but did affect feed preference and rumen fermentation. After transition to a free-choice diet, HO calves consumed more hay (550.2 g/d) than CON (177.4 g/d) and COH (396.4 g/d) calves on the first day only. However, COH calves consumed a greater amount of hay, resulting in a higher ratio of hay to total solids compared with either CON or HO calves during d 57 to 70. Upon transition to a TMR, a similar sorting pattern was exhibited between treatments, with calves sorting against the long and for the fine particle fractions. Although no significant long-term effects of different EFE on rumen pH, volatile fatty acids, and blood glucose persisted at wk 27 (from d 190 to 196), calves exposed to COH early had an improved ability to sort for long feed particles compared with CON and HO calves later in life. Our results suggest that EFE could influence choice of feed immediately after weaning and may have long-lasting effects on feed preference in heifers later in life. Further studies with more calves are recommended.     

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.     

Soymilk as a novel milk replacer to stimulate early calf starter intake and reduce weaning age and costs

The primary objective was to determine the effects of partial replacement of whole milk with soymilk on preweaning calf performance and weaning costs. Following 3 d of colostrum and transition milk feeding, 18 male and 9 female neonatal Holstein calves (41.6 ± 1.6 kg of body weight; mean ± SE) were assigned in a completely randomized design to 3 treatments offered at 10% of body weight (wet basis) including 1) whole milk (control), 2) 75% whole milk + 25% soymilk (S25), or 3) 50% whole milk + 50% soymilk (S50). The weaning criterion was defined as the calf age at a daily intake of ≥900 g of starter concentrate. During the first 2 wk of the experiment, treatments did not differ in starter intake and fecal score. Calves fed S25 gained similar amount of body weight as calves fed whole milk diet. By 49 d of age, also, calves on S25 gained similar body weight as did calves on whole milk diet. Calves on S25 and S50 achieved the weaning criterion, respectively, about 10 and 12 d earlier than did peers on whole milk. The soymilk-fed calves consumed less milk than control calves to meet the weaning criterion owing to promoted starter intake. Feed-related weaning costs dropped by about 35% when soymilk was fed because whole milk was about 50% more expensive than both soymilk and starter concentrate. Feeding soymilk at up to 50% of the milk diet maintained health during the first 2 to 4 wk of age when the neonate calf is highly sensitive to nonmilk proteins and plant antinutrients. Results introduce soymilk as an economic partial substitute for whole milk in calf-raising facilities.     

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.     

Effect of parity and stage of lactation on feed sorting behavior of lactating dairy cows

The objectives of this study were to determine if feed sorting differs between primiparous (PP) and multiparous (MP) cows, if sorting changes from the period of peak lactation to peak dry matter intake (DMI), and whether feed sorting affects efficiency of production. Data on DMI, milk production, feed sorting (particle size of offered and refused feed), and energy status (plasma nonesterified fatty acid, β-hydroxybutyrate, insulin and glucose concentration) were collected on 30 PP and 30 MP lactating Holstein dairy cows, individually housed and fed in tie-stalls, during 3 wk (wk 2, 6, and 10) over 10 wk of a lactation study. Cows averaged 53, 81, and 109 ± 10 d in milk (DIM) at the beginning of each of the 3 recording weeks. To determine sorting, feed samples were separated with a particle separator that had 3 screens (19, 8, and 1.18 mm) and a bottom pan, resulting in 4 fractions (long, medium, short, fine). Over the study period, MP cows consumed more DM and produced more milk than did the PP cows, but had similar efficiency of production (kg of milk/kg of DMI), and similar levels of plasma indicators of energy status. Across the study period, DMI increased, whereas milk yield decreased, resulting in decreased efficiency of milk production as cows moved further into lactation. All cows had higher nonesterified fatty acid and lower insulin concentrations in plasma at 53 DIM compared with at 81 and 109 DIM, suggesting they were mobilizing more body fat at that earlier stage of lactation. Across periods, all cows sorted against the longest ration particles, did not sort the medium ration particles, and sorted for fine ration particles; as a result, all cows consumed less neutral detergent fiber (NDF) and physically effective NDF (proportion of NDF retained on the 19- and 8-mm screens of the particle separator) than predicted. Greater selection against the longest ration particles was associated with greater efficiency of milk production; however, this sorting pattern also tended to be associated with lower milk fat percentage. The extent of the observed sorting against the longest, physically effective ration particles and for the finest ration particles was greater for PP cows than for MP cows across all 3 observation periods. Feed sorting remained consistent in cows across the DIM evaluated in this study and that this sorting behavior can affect the efficiency of milk production as well as milk fat percentage. Further, PP cows engage in more sorting of their ration than MP cows.     

What do preweaned and weaned calves need in the diet: A high fiber content or a forage source?

The objective of this study was to determine whether the improvement of performance of young calves associated with the supplementation of chopped grass hay reported in some studies is due to an increase in the total neutral detergent fiber (NDF) content of the consumed diet or to the provision of chopped grass hay. Sixty-three Holstein calves [9 ± 4.4 d old; mean ± standard deviation (SD)] were randomly distributed in 4 treatments resulting from the combination of 2 levels of NDF content of a pelleted starter and the supply or absence of forage provision: low-NDF starter (18%) with or without chopped oat hay, and high-NDF starter (27%) with or without chopped oat hay. All animals were fed the same milk replacer (21% crude protein and 19.2% fat) at the rate of 4 L/d at 15% dry matter from d 1 to 34, and 2 L/d at 15% dry matter from d 35 to 42 (weaning). The study finished 2 wk after weaning. Body weight was measured weekly and individual calf starter and hay intake was recorded daily. On d 50, blood samples were drawn 2 h after the morning concentrate offer to determine serum glucose and insulin concentrations. On d 52, samples of ruminal fluid were obtained via an esophageal tube, and pH was measured immediately. During the preweaning period, pelleted starter intake was similar among treatments, but average daily gain tended to be greater in low- than in high-NDF treatments (0.69 vs. 0.63 ± 0.020 kg/d, respectively; mean ± SD). However, during the 2 wk after weaning, supplementation of forage improved pelleted starter intake and average daily gain without affecting the gain-to-feed ratio. Probably, the greater pelleted starter intake observed in forage-supplemented calves was mainly due to the greater ruminal pH found in forage-supplemented calves compared with forage-deprived calves (5.81 vs. 5.05 ± 0.063, respectively). Blood insulin-to-glucose ratio was greater in forage-supplemented compared with unsupplemented calves [mean ± SD; 6.53 vs. 4.24 ± 0.125 insulin (ng/L)-to-glucose (mg/dL) ratio, respectively]. In conclusion, a low-NDF pelleted starter is recommended during the preweaning period, and the provision of chopped hay is necessary right after weaning to improve calf performance.     

Replacing concentrates with a high-quality hay in the starter feed in dairy calves: I. Effects on nutrient intake,growth performance,and blood metabolic profile

Concentrate-rich starter feeds are commonly fed to dairy calves to stimulate early solid feed intake and growth performance; yet, starter feeds lacking in forage fiber may jeopardize gut development. This research primarily aimed to test a complete or partial replacement of concentrates with hay of different qualities in the starter feed on nutrient intake, growth performance, apparent total-tract digestibility (ATTD) of nutrients, and blood metabolites in dairy calves. Immediately after birth, 40 Holstein Friesian calves were randomly allocated to 1 of 4 starter diets, which differed in hay quality and concentrate inclusion [MQH = 100% medium-quality hay, 9.4 MJ of metabolizable energy (ME), 149 g of crude protein (CP), 522 g of neutral detergent fiber (NDF)/kg of dry matter (DM); HQH = 100% high-quality hay, 11.2 MJ of ME, 210 g of CP, 455 g of NDF/kg of DM; MQH⁺C = 30% medium-quality hay + 70% starter concentrate; HQH⁺C = 30% high-quality hay + 70% starter concentrate]. The concentrate consisted mainly of grains, oilseeds, and mineral supplements (13.5 MJ of ME, 193 g of CP, 204 g of NDF/kg of DM). Calves were used in the experiment from d 1 to 99 of life. During the first 4 wk, all calves were fed acidified whole milk ad libitum, and afterward they were gradually weaned from wk 5 to 12. Calves had ad libitum access to their starter diets and water throughout the experiment. Milk, water, and solid feed intake was recorded daily, live weight was measured once a week, and blood samples were collected on d 1, 3, 7, 21, 49, 77, and 91 and analyzed for selected metabolites. The ATTD was measured in wk 14 of life. Total DM intake and daily weight gain of calves were not affected by the starter feed during the first 8 wk of life. However, from wk 9 to 14, calves fed the MQH diet had lower DM, ME, and CP intake and gained less weight than calves from the other experimental groups. Feeding the HQH diet resulted in similar CP and ME intake and growth performance compared with calves receiving diets containing concentrates. Furthermore, feeding the HQH diet improved the ATTD of NDF, resulting in similar ATTD of organic matter with the HQH⁺C and MQH⁺C groups. Interestingly, calves fed the HQH⁺C diet showed less sorting for concentrate, compared with the MQH⁺C group. Concentration of blood metabolites, including glucose, lactate, insulin, nonesterified fatty acids, triglycerides, and total protein, did not differ after the first week of life. However, serum β-hydroxybutyrate was higher in calves fed the HQH diet starting from wk 11. Both groups fed the hay-only diets maintained higher cholesterol levels after weaning compared with the groups fed hay-concentrate mixtures. In conclusion, feeding high-quality hay can fully replace starter concentrates in the feeding of dairy calves without adverse effects on performance during the rearing period, while increasing forage fiber intake and utilization, which enhanced ruminal ketogenesis and cholesterogenesis around weaning. Further research is needed to evaluate long-term effects of feeding high-quality hay on health and development of dairy calves, especially in terms of the observed improvements in ruminal ketogenesis and cholesterogenesis around weaning.     

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

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

The effect of palatability of protein source on dietary selection in dairy calves

Evidence has shown that soybean meal is perceived as more palatable than canola meal by dairy calves in short-term preference tests. This study evaluated the effect of protein source on longer-term dietary selection of dairy calves. In experiment 1, 40 Holstein bull calves (11.4 ± 4.3 d of age) were randomly assigned to 1 of 2 choice diets for 6 wk: base starter pellet (S; 12% crude protein; CP) and high-protein pellet (40% CP) containing either (1) soybean meal (SB) or (2) canola meal (CM). In wk 7 to 8, all calves were offered a single pelleted diet containing the protein source to which they were previously exposed. In experiment 2, 22 Holstein bull calves (9.9 ± 4.6 d of age) were offered, for 6 wk, a choice of 2 mixed pelleted diets: (1) 70% S and 30% SB (SB mix), or (2) 70% S and 30% CM (CM mix). In wk 7 to 8, calves were randomly assigned to 1 of 2 choice diets, as in experiment 1: (1) SB + S, or (2) CM + S. All feeds were provided ad libitum. Calves received 6 L/d of milk replacer [0.75 kg/d of dry matter (DM)] for the duration of both experiments. Feed intake was recorded daily and calves were weighed every 14 d. Feeds were sampled weekly to analyze DM and nutrient intake. Mixed diets in experiment 2 were analyzed for CP in wk 4 and 6 to assess feed sorting (calculated as actual CP intake as a percentage of predicted intake). In experiment 1, calves offered SB + S in wk 1 to 6 consumed more high-protein pellet than calves offered CM + S [73 vs. 42% of DM intake (DMI)] and, consequently, more CP (168 vs. 117 g/d). Solid feed DMI and average daily gain were similar between treatments. When offered a single diet in wk 7 to 8, calves offered starter containing soybean meal increased intake to a greater extent than calves offered the starter containing canola meal. In experiment 2, calves preferred the SB mix to CM mix (preference ratio: 0.7). Calves consumed more CP than predicted from SB mix in wk 4 and 6 (108 ± 2.0%), indicating that they were sorting in favor of SB. In contrast, calves consumed less CP than predicted from CM mix in wk 4 (81.48 ± 4.1%), indicating that they were sorting against CM. When assigned to choice treatments in wk 7 to 8 of experiment 2, calves offered SB + S consumed more protein pellet than calves offered CM + S (81 vs. 31% DMI) and consumed more CP (378 vs. 196 g/d). Average daily gain was greater for calves offered SB + S but DMI was similar. Overall, these results suggest that dietary selection was influenced by innate feed preferences, and milk-fed calves may not be sensitive to protein imbalances in their diet.     

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

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

The effects of teat bar design and weaning method on behavior, intake, and gain of dairy calves

The aim of the present study was to investigate the effects of teat-feeding method and weaning method on behavior, milk and concentrate intake, and weight gain of group-housed dairy calves. Forty-eight calves were housed in groups of 4 and offered 6 L of whole milk per calf in 2 daily feedings. In 6 of the 12 group pens, the calves were offered the milk in a teat bar with a separate milk compartment for each teat, whereas in the remaining 6 pens, the calves were offered the milk in a teat bar with all teats connecting to 1 shared milk compartment. Calves were gradually weaned off milk by reducing the volume of milk over a 10-d period, starting at an average age of 47 d. In 6 pens (3 pens with each of the 2 milk-feeding treatments), calves were weaned by volume reduction, whereas in the remaining pens, the calves were weaned by diluting the milk with water (WD) and maintaining the same total volume of liquid. Daily concentrate intake per pen was recorded during weaning and 1 wk after weaning. Behavior was recorded around milk feeding, by direct observation on 1 occasion before and on 1 occasion during weaning, and by video on 1 occasion before and 2 occasions during weaning. Furthermore, the behavior was recorded during the 15 h of light on 1 occasion during weaning. Individual milk intake was measured twice by weighing the calves immediately before and after milk feeding. The calves fed via a separate teat bar switched between teats more often than calves fed with a shared teat bar. There was greater variation in the duration of ingesting milk within groups fed via a separate teat bar, but no effect of teat bar design was found on the variation in milk intake within the groups. Calves fed via a separate teat bar took longer to start eating concentrate after milk feeding than calves fed with a shared teat bar. The WD calves had a lower concentrate intake during weaning than weaned by volume reduction calves. The WD calves were lying down less during the 30 min after milk feeding and during the 15 h of light, although they had a shorter latency to lie down after milk feeding. In conclusion, a separate teat bar increased teat switching, increased variation in duration of ingesting milk, and increased the latency to eat concentrates after milk feeding. There was no effect of the teat bar design on feed intake or weight gain. However, weaning the calves by gradually diluting the milk with water reduced lying during weaning and reduced the concentrate intake during and after weaning.     

Effects of supplementing concentrates differing in carbohydrate composition in veal calf diets: II. Rumen development

The objective of this experiment was to examine the effects of concentrates in feed, differing in carbohydrate source, on the rumen development of veal calves. For this purpose, 160 male Holstein Friesian × Dutch Friesian crossbred calves were used in a complete randomized block design with a 5 × 2 factorial arrangement. Dietary treatments consisted of 1) a milk replacer control, 2) a pectin-based concentrate, 3) a neutral detergent fiber-based concentrate, 4) a starch-based concentrate, and 5) a mixed concentrate (equal amounts of the concentrates in treatments 2, 3, and 4). Concentrate diets were provided as pellets in addition to a commercial milk replacer. Calves were euthanized at either 8 or 12 wk of age. Plasma acetate and β-hydroxybutyrate (BHBA) were measured as indicators of rumen development. Empty rumen weight was determined, and wall samples were taken at slaughter. In most calves, a poorly developed rumen mucosa was observed. Coalescing rumen papillae with embedded hair, feed particles, and cell debris were found in all calves fed the concentrate diets. Calves fed concentrates had significantly heavier rumens than calves fed the control diet. In the dorsal location of the rumen, calves fed concentrate diets showed an increased ratio of mucosa to serosa length compared with calves fed the control diet, whereas in the ventral location only, calves fed the pectin and mixed diets showed larger ratios of mucosa to serosa length. Mucosa thickness and muscle thickness were greater in the ventral and dorsal locations of the rumen, respectively. In both locations, the NDF diet resulted numerically in the lowest mucosa thickness and highest muscle thickness among the concentrate treatments. At 8 wk, calves fed the concentrate diets had higher plasma acetate concentrations than calves on the control treatment. However, at 12 wk, only NDF-fed calves showed significantly higher plasma acetate concentrations. The plasma BHBA concentrations of calves at 8 wk of age fed the pectin and mixed diets were higher than those of the control diet-fed calves. At 12 wk, no differences in BHBA concentrations were observed among treatments. Results of a principal component analysis indicated that, in addition to rumen volatile fatty acid concentrations, other factors were likely to affect rumen development, and that the relationships between rumen development and individual types of volatile fatty acids present in the rumen liquor were similar. Also, variations in rumen development coincided with variations in plasma acetate and BHBA concentrations.     

The effects of feed bunk competition on the feed sorting behavior of close-up dry cows

The objectives of this research were to describe the feed sorting, feeding behavior, and feed intake of cows consuming a close-up ration and to determine if these behaviors are affected by competition for access to the feed bunk. Thirty-six dry Holstein cows, consuming a close-up total mixed ration diet, were assigned to 1 of 2 treatments: 1) noncompetitive (1 cow/feed bin) or 2) competitive (2 cows/feed bin). Dry matter intake, feeding behavior, and sorting behavior were monitored for each feed bin on 4 separate days during wk 2 and 3 before the anticipated calving dates of the cows. Fresh feed and orts were sampled daily from each bin and were subjected to particle size analysis. The particle size separator consisted of 3 screens (18, 9, and 1.18 mm) and a bottom pan resulting in 4 fractions (long, medium, short, and fine). Sorting was calculated as the actual intake of each particle size fraction expressed as a percentage of the predicted intake of that fraction. Regardless of treatment, the cows sorted against long particles and for short and fine particles. Competition at the feed bunk had no effect on the sorting behavior, dry matter intake, or feeding time of the cows, but did dramatically increase the feeding rate of the cows. The competitively fed cows also had fewer meals per day, and tended to have larger and longer meals. Our results suggest that increased competition at the feed bunk promotes feeding behavior patterns that will likely increase the between-cow variation in composition of total mixed ration consumed.     

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.     

Effects of roughage source,amount, and particle size on behavior and gastrointestinal health of veal calves

The European Union 1997 Directive, stipulating that veal calves should be fed a minimum of 50 to 250 g of fibrous feed from 8 to 20 wk of age, is vague. A fibrous feed ration maximum of 250 g has been implicated in welfare issues, namely the occurrence of abnormal oral behaviors and poor gastrointestinal health. Past research suggests that this amount is insufficient to prevent the development of abnormal oral behaviors and enabling good rumen development. Different sources and particle sizes of roughage could lead to very different welfare outcomes. In a 3 × 2 × 2 factorial design, 240 group-housed calves (10 ± 1 d; 46.1 ± 0.1 kg) were fed different roughage sources (straw, maize silage, or maize cob silage; the latter 2 were dried and provided no extra moisture compared with straw) in 2 amounts (250 or 500 g of dry matter per day), and 2 particle sizes (chopped or ground). Roughage was supplemented to milk replacer (MR) from 2 wk after arrival. In addition, 60 calves were fed 1 of 3 additional control treatments: MR only (n = 20), MR plus an iron supplement (n = 20), or MR plus ad libitum hay (n = 20). Oral behaviors were recorded using instantaneous scan sampling at 2-min intervals for 2 h in 3 periods per day, at 12 and 22 wk of age. Calves were slaughtered at 24 wk of age and rumen and abomasal health parameters were recorded. Limited provision of straw resulted in behavior comparable with that from unlimited provision of hay, with reduced tongue playing and oral manipulation of the environment, as well as increased chewing compared with diets with no roughage supplement. Straw prevented ruminal hairballs, but impaired rumen development and increased abomasal damage. A higher ration of roughage increased chewing (12 wk), decreased oral manipulation of the trough (12 and 22 wk) and the pen (22 wk), and increased rumen weight. However, more roughage led to increased abomasal damage for certain parameters. Longer feed particles had no obvious benefits for behavior, but decreased hairball prevalence. Overall, unlimited hay had the highest benefit for both behavior and gastrointestinal health. Adding iron to the MR did not alter behavior or gastrointestinal health compared with MR without iron supplement. This study demonstrated that different roughage sources, amounts, and particle sizes have different effects on veal calf behavior and gastrointestinal health, and hence on veal calf welfare.     

Nutrient intake and feeding behavior of growing dairy heifers: effects of dietary dilution

The objective of this study was to determine how the addition of straw to a total mixed ration offered to growing dairy heifers affects their nutrient intake and feeding behavior. Six prepubescent Holstein heifers (226.2 ± 6.3 d old and weighing 250.1 ± 17.7 kg), fed once per day for 1.0 kg/d of growth, were subjected to each of 3 treatment diets using a replicated 3 × 3 Latin square design. The treatment diets were 1) control (17.0% corn silage, 52.1% grass silage, 30.9% concentrate), 2) control diet with 10% straw, and 3) control diet with 20% straw. Dry matter intake and feeding behavior were monitored for 7 d for each animal on each treatment. Fresh feed and orts were sampled on the last 3 d of each treatment period for each heifer and were then subjected to particle size analysis. The particle size separator contained 3 screens (19, 8, and 1.18 mm) and a bottom pan, resulting in 4 fractions (long, medium, short, and fine). Sorting activity for each fraction was calculated as actual intake expressed as a percentage of the predicted intake. Heifers sorted against long particles and for short particles on all 3 diets. On the 10 or 20% straw diets the heifers sorted for medium particles. Heifers also sorted for fine particles on the 20% straw diet. There was a linear increase in sorting for medium, short, and fine particles with increased straw in the diet. Dry matter intake linearly decreased with increased straw in the diet. Feeding time and meal duration increased linearly with the addition of straw to the diet, whereas feeding rate, meal size, and meal frequency decreased with the addition of straw. Requirements for maintenance and growth of 1.0 kg/d were sufficiently met when the animals consumed the control and 10% straw diet. On the 20% straw diet the animals consumed sufficient nutrients to achieve a 0.9 kg/d growth rate. These results indicate that the addition of straw to the diet of prepubescent heifers strongly influences their sorting behavior. Despite this sorting, the results suggest that a low-quality feedstuff may be included in the diet to target nutrient intake and reduce feed costs without negatively affecting feeding behavior or growth potential.