Effects of compound probiotics on growth performance,rumen fermentation,blood parameters,and health status of neonatal Holstein calves

This study aimed to investigate the effects of compound probiotics (consisting of 10⁸ cfu/g of Lactobacillus plantarum, 10⁸ cfu/g of Pediococcus acidilactici, 10⁸ cfu/g of Pediococcus pentosaceus, 10⁷ cfu/g of and Bacillus subtilis) on growth performance, rumen fermentation, bacteria community, blood parameters, and health status of Holstein calves at the first 3 mo of age. Forty-eight newborn calves were randomly divided into the following 3 groups: control group (milk replacer with no compound probiotics), low compound probiotics group (milk replacer + 0.12 g of compound probiotics per head per day), and high compound probiotics group (HP; milk replacer + 1.2 g of compound probiotics per head per day). Starter pellets of the low compound probiotics and HP groups were coated with 0.05% compound probiotics. Milk replacer was provided from 2 to 63 d of age (6 L at 2–10 d, 8 L at 11–42 d, 6 L at 43–49 d, 4 L at 50–56 d, and 2 L at 57–63 d), and starter pellets were provided ad libitum from 7 to 90 d of age. Body weight and body size (d 1, 30, 60, and 90), blood (d 40 and 80), and rumen fluid (d 90) were analyzed using the one-way ANOVA procedure; fecal score was recorded daily and analyzed as repeated measures using the mixed model procedure. Results showed that diet supplemented with compound probiotics had no effects on the body weight, average daily gain, dry matter intake, and feed efficiency. At 90 d of age, diet supplemented with compound probiotics decreased the withers height. Immunity activities increased in the HP group, supported by the increased concentrations of serum total protein and immunoglobulins at 40 d of age, and by the increased activity of superoxide dismutase at 80 d of age. Diet supplemented with compound probiotics altered rumen fermentation, indicated by the decreased rumen acetic acid and propionic acid, and the increased butyric acid concentrations. Diet supplemented with compound probiotics improved the health status of calves, indicated by the decreased fecal score at 3 wk of age and the decreased medicine treatments. In summary, although diet supplemented with HP decreased the withers height, this level of probiotics is recommended to improve rumen development and health status of newborn Holstein calves.     

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

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

Effects of peripartal yeast culture supplementation on lactation performance,blood biomarkers,rumen fermentation,and rumen bacteria species in dairy cows

Feeding yeast culture fermentation products has been associated with improved feed intake and milk yield in transition dairy cows. These improvements in performance have been further described in terms of rumen characteristics, metabolic profile, and immune response. The objective of this study was to evaluate the effects of a commercial yeast culture product (YC; Culture Classic HD, Phibro Animal Health) on performance, blood biomarkers, rumen fermentation, and rumen bacterial population in dairy cows from −30 to 50 d in milk (DIM). Forty Holstein dairy cows were enrolled in a randomized complete block design from −30 to 50 DIM and blocked according to expected calving day, parity, previous milk yield, and genetic merit. At −30 DIM, cows were assigned to either a basal diet plus 114 g/d of ground corn (control; n = 20) or a basal diet plus 100 g/d of ground corn and 14 g/d of YC (n = 20), fed as a top-dress. Cows received the same close-up diet from 30 d prepartum until calving [1.39 Mcal/kg of dry matter (DM) and 12.3% crude protein (CP)] and lactation diet from calving to 50 DIM (1.60 Mcal/kg of DM and 15.6% CP). Blood samples and rumen fluid were collected at various time points from −30 to 50 d relative to calving. Cows fed YC compared with control showed a trend for increased energy-corrected milk (+3.2 kg/d). Lower somatic cell counts were observed in YC cows than in control. We detected a treatment × time interaction in nonesterified fatty acids (NEFA) that could be attributed to a trend for greater NEFA in YC cows than control at 7 DIM, followed by lower NEFA in YC cows than control at 14 and 30 DIM. In the rumen, YC contributed to mild changes in rumen fermentation, mainly increasing postpartal valerate while decreasing prepartal isovalerate. This was accompanied by alterations in rumen microbiota, including a greater abundance of cellulolytic (Fibrobacter succinogenes) and lactate-utilizing bacteria (Megasphaera elsdenii). These results describe the potential benefits of supplementing yeast culture during the late pregnancy through early lactation, at least in terms of rumen environment and performance.     

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 supplemental butyrate and weaning on rumen fermentation in Holstein calves

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

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

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

Effects of 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.     

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.     

Growth performance,digestibility, blood metabolites,ruminal fermentation,and bacterial communities in response to the inclusion of gallic acid in the starter feed of preweaning dairy calves

The objective of this study was to evaluate the effects of feeding gallic acid on the growth, nutrient digestibility, plasma metabolites, rumen fermentation, and bacterial community in the rumen fluid and feces of preweaning calves. Thirty-six female Holstein calves with similar ages (means ± SD; 3.1 ± 1.39 d) and body weights (40.8 ± 2.87 kg) were randomly assigned to receive 3 treatments. Calves were fed 1 of 3 treatments as follows: basal diet with no gallic acid (control), 0.5 g/kg gallic acid in starter diet (low), and 1 g/kg gallic acid in starter diet (high). The results showed that feeding gallic acid increased growth by improving the starter intake and average daily gain of the calves. The fecal score tended to decrease in a linear manner with the addition of gallic acid. Total-tract apparent protein digestibility tended to increase linearly with feeding gallic acid. Feeding gallic acid led to a linear increase in the plasma total protein and β-hydroxybutyrate levels. In addition, feeding gallic acid linearly increased catalase and total antioxidant capacity levels and decreased malondialdehyde and tumor necrosis factor-α concentrations. The concentrations of total volatile fatty acids, propionate, butyrate, and valerate in the rumen fluid increased linearly with the addition of gallic acid, resulting in a linear pH reduction. Feeding gallic acid linearly increased the relative abundances of Prevotella_1, Saccharofermentans, and Prevotellaceae_UCG-001 and linearly decreased the relative abundance of Prevotella_7 in the rumen fluid. The Shannon index of ruminal bacterial communities linearly increased by feeding gallic acid. Feeding gallic acid linearly increased the relative abundances of Ruminococcaceae_UCG-005, Bacteroides, and Christensenellaceae_R-7_group in the feces. In summary, feeding gallic acid improved growth, antioxidant function, and rumen fermentation and altered the bacterial community in the rumen fluid and feces of preweaning dairy calves.     

Effects of weaning and ionophore supplementation on selected blood metabolites and growth in dairy calves

Dairy calf weaning results in blood ketone concentrations in excess of mature rates of use and can result in excretion of ketones in urine representing a loss of energy. Lasalocid is frequently supplemented as an anticoccidial agent in calf starters; however, in mature ruminants it is known to alter molar ratios of ruminal volatile fatty acids (VFA). Effects of weaning transition and postweaning ionophore supplementation on body weight, dry matter (DM) intake, average daily gain (ADG), and blood concentrations of glucose, acetoacetate, β-hydroxybutyrate (BHBA), lactate, pyruvate, nonesterified fatty acids (NEFA), VFA, insulin, and glucagon were examined using Jersey bull calves (n = 24) over 16 wk. Calves were blocked into groups of 2 according to birth date and weight and randomly assigned to receive either a commercial pelleted starter (control), or the same diet containing lasalocid (TRT; 83 mg/kg of DM). Calves were fed milk replacer from d 3 to 34 (d 3 to 20 = 454 g/d at 12% solids; d 21 to 34 = 568 g/d at 15% solids), from d 35 to 48 calves received both replacer (d 35 to 41 = 454 g/d; d 42 to 38 = 227 g/d) and free access to control or TRT starter, and from d 49 to 112 received ad libitum control or TRT. Body weight and jugular blood metabolite concentrations were measured and recorded weekly. Postweaning DM intake, average daily gain, and feed:gain did not differ between control and TRT calves. Glucose and NEFA concentrations did not differ between control and TRT, but declined with age. Insulin and glucagon concentrations did not differ between control and TRT, but glucagon concentrations increased with weaning. Total VFA significantly increased following introduction of solid feed at d 35 in both groups with an apparent 1-wk lag in TRT VFA increases compared with control. Jugular acetate and butyrate concentrations were greater in control calves than TRT calves during wk 7. Propionate concentrations did not differ between control and TRT at any time following weaning. Blood BHBA concentrations were greater in control than TRT during wk 8 and 9. Thus, consumption of starter supplemented with lasalocid delayed peak acetate and butyrate and lowered peak BHBA concentrations. However, supplementation at concentrations currently recommended for control of coccidiosis did not appear to be sufficient to enhance growth or efficiency during the wk 7 to 16 postweaning interval for this sample size.     

Effects of yeast culture supplementation on lactation performance and rumen fermentation profile and microbial abundance in mid-lactation Holstein dairy cows

The continuous trend for a narrowing margin between feed cost and milk prices across dairy farms in the United States highlights the need to improve and maintain feed efficiency. Yeast culture products are alternative supplements that have been evaluated in terms of milk performance and feed efficiency; however, less is known about their potential effects on altering rumen microbial populations and consequently rumen fermentation. Therefore, the objective of this study was to evaluate the effect of yeast culture supplementation on lactation performance, rumen fermentation profile, and abundance of major species of ruminal bacteria in lactating dairy cows. Forty mid-lactation Holstein dairy cows (121 ± 43 days in milk; mean ± standard deviation; 32 multiparous and 8 primiparous) were used in a randomized complete block design with a 7-d adaptation period followed by a 60-d treatment period. Cows were blocked by parity, days in milk, and previous lactation milk yield and assigned to a basal total mixed ration (TMR; 1.6 Mcal/kg of dry matter, 14.6% crude protein, 21.5% starch, and 38.4% neutral detergent fiber) plus 114 g/d of ground corn (CON; n = 20) or basal TMR plus 100 g/d of ground corn and 14 g/d of yeast culture (YC; n = 20; Culture Classic HD, Cellerate Yeast Solutions, Phibro Animal Health Corp.). Treatments were top-dressed over the TMR once a day. Cows were individually fed 1 × /d throughout the trial. Blood and rumen fluid samples were collected in a subset of cows (n = 10/treatment) at 0, 30, and 60 d of the treatment period. Rumen fluid sampled via esophageal tubing was analyzed for ammonia-N, volatile fatty acids (VFA), and ruminal bacteria populations via quantitative PCR amplification of 16S ribosomal DNA genes. Milk yield was not affected by treatment effects. Energy balance was lower in YC cows than CON, which was partially explain by the trend for lower dry matter intake as % body weight in YC cows than CON. Cows fed YC had greater overall ruminal pH and greater total VFA (mM) at 60 d of treatment period. There was a contrasting greater molar proportion of isovalerate and lower acetate proportion in YC-fed cows compared with CON cows. Although the ruminal abundance of specific fiber-digesting bacteria, including Eubacterium ruminantium and Ruminococcus flavefaciens, was increased in YC cows, others such as Fibrobacter succinogenes were decreased. The abundance of amylolytic bacteria such as Ruminobacter amylophilus and Succinimonas amylolytica were decreased in YC cows than CON. Our results indicate that the yeast culture supplementation seems to promote some specific fiber-digesting bacteria while decreasing amylolytic bacteria, which might have partially promoted more neutral rumen pH, greater total VFA, and isovalerate.     

Effects of preweaning total plane of milk intake and weaning age on intake,growth performance,and blood metabolites of dairy calves

The objective of this study was to evaluate the effects of preweaning total plane of milk intake and weaning age on intake, growth performance, and blood metabolites of dairy calves. A total of 48 Holstein calves (40 ± 1.6 kg of body weight) were used in a 2 × 2 factorial arrangement with the factors of weaning age (d 60 vs. 75) and the total plane of milk intake (medium vs. high) during the preweaning period. Calves were assigned to 1 of 4 treatments: (1) calves fed medium plane of milk (MPM) intake and weaned on d 60 of age (MPM-60d, 4 L/d of milk from d 3 to 10, 6 L/d of milk from d 11 to 55, and 3 L/d of milk from d 56 to 60 of age; total milk intake = 317 L), (2) calves fed MPM intake and weaned on d 75 of age (MPM-75d, 4 L/d of milk from d 3 to 10 and 4.5 L/d of milk from d 11 to 70 of age followed by feeding 2.25 L/d of milk from d 71 to 75 of age; total milk intake = 313 L), (3) calves fed high plane of milk (HPM) intake and weaned on d 60 of age (HPM-60d, 4 L/d of milk from d 3 to 10, 6 L/d of milk from d 11 to 20, and 8.5 L/d of milk from d 21 to 55 followed by feeding 4.25 L/d of milk from d 56 to 60 of age; total milk intake = ～411 L); and (4) calves fed HPM intake and weaned on d 75 (HPM-75d, 4 L/d of milk from d 3 to 10, and 6 L/d of milk from d 11 to 70 of age followed by feeding 3 L/d of milk from d 71 to 75 of age; total milk intake = 407 L) with no milk refusals. All of the calves were monitored up to d 90 of age. Regardless of weaning age, starter feed intake and dry matter intake (% of body weight) were lower in calves fed HPM compared with those receiving MPM. A tendency for the plane of milk intake × weaning age interaction was observed for metabolizable energy intake with the highest value was recorded with the HPM-75d calves. The lowest efficiency of metabolizable energy intake and average feed efficiency was observed in HPM-60d calves throughout the experimental period as compared with the other groups. An interaction was found between the total plane of milk intake and weaning age regarding effects on total average daily gain, average daily gain/metabolizable energy intake, feed efficiency, final body weight, and plasma β-hydroxybutyrate levels with the highest values measured in HPM-75d calves. Weaning on d 75 versus d 60 improved wither height and hip width, which tended to increase body length at the end of the trial. The results suggest that calves fed high amounts of milk during their preweaning period benefit from extending the time of weaning from 60 to 75 d of age based on average daily gain, feed efficiency, and final body weight.     

Influence of weaning method on health status and rumen development in dairy calves

In the artificial rearing of dairy calves, the same feeding plan is applied to all animals during the milk-feeding period, with individual differences attributable to development or health status rarely considered. The aim of this study was 1) to analyze whether the parameters of feeding behavior automatically recorded by a feeding computer and weight gain are suitable for predicting the health status and rumen development of male dairy calves, and 2) to compare a conventional weaning method (end of milk provision at 12 wk of age, n = 23 calves) with a concentrate-dependent weaning method (with reduction in the milk amount depending on the consumption of concentrate, n = 24). The health status of each animal was evaluated daily by a scoring list (health score), and body temperature was measured automatically during each milk intake. In addition, the number of veterinary treatments per calf was recorded. Rumen development was assessed by measuring rumen papillae in 8 rumen areas after slaughter (n = 24, half of each treatment group). During the milk-feeding period, body temperature was elevated (≥39.5°C) on 40.8 and 43.2% of all days for calves on the concentrate-dependent weaning method and the conventional weaning method, respectively. Hay and concentrate intake (but not milk intake) and weight gain were clearly affected by health status. In addition, health score and the probability of being treated by a veterinarian were significantly related to decreases in concentrate consumption. During the milk-feeding period, increased body temperature, an increased number of veterinary treatments, and decreases in milk consumption were all associated with reduced weight gain. Calves on the concentrate-dependent weaning method were weaned at an average age of 76 d, which was significantly shorter than the age at the end of milk provision for conventionally fed calves (84 d). Weight gain and health status did not differ between treatment groups. Weight gain was positively associated with papillae length. A treatment effect on rumen development could not be found. We conclude that the concentrate-dependent weaning method allows a faster physiological development without any negative impact on rumen development, weight gain, or health status; we therefore recommend its use in practice.     

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

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

Supplementation of lysolecithin in milk replacer for Holstein dairy calves: Effects on growth performance,health, and metabolites

Lysolecithin is an antiinflammatory emulsifier associated with improved apparent digestibility of total dietary fat and improved feed efficiency in dairy cattle. However, it is unknown if lysolecithin (LYSO) improves performance in calves. Moreover, since many conventional milk replacers use vegetable-sourced fat (e.g., palm oil), nutrient absorption and fecal score may be affected in neonatal calves. Thus, the objective of this study was to evaluate the effects of LYSO supplemented in milk replacer on performance, metabolites, and gut health of preweaned dairy calves. Holstein calves (n = 32) with adequate passive transfer were assigned in pairs (16 blocks) balanced by birth weight, date of birth, and sex at 1 d of age to randomly receive either LYSO (mixed in 2 milk replacer feedings at a rate of 4 g/d Lysoforte, Kemin Industries Inc., Des Moines, IA) or a milk replacer control (nothing added). Both treatments were fed 6 L/d milk replacer [22.5% crude protein, 16.2% crude fat (vegetable oil fat source) on a dry matter basis with 14% solids] by bucket in 2 daily feedings for 56 d. Calves were individually housed in wooden hutches and offered a commercial calf starter (24.6% crude protein and 13.9% neutral detergent fiber) and water by bucket ad libitum. Feed refusals and calf health was assessed daily. Weights and blood metabolites (glucose, total serum protein, albumin, creatinine, triglycerides, and cholesterol) were sampled weekly, and calves completed the study before weaning at 56 d of age. The effects of LYSO on calf average daily gain, feed efficiency, and blood metabolites were evaluated using a linear mixed model with time as a repeated measure, calf as the subject, and block as a random effect in SAS (SAS Institute Inc., Cary, NC). The effect of LYSO to improve the odds of abnormal fecal score was evaluated using a logistic model. Supplementation of LYSO increased average daily gain (control 0.28 ± 0.03 kg; LYSO 0.37 ± 0.03 kg; least squares means ± standard error of the mean) and increased feed efficiency (gain-to-feed; control 0.25 ± 0.03; LYSO 0.32 ± 0.03). Similarly, LYSO calves had a higher final body weight at d 56 (control 52.11 ± 2.33 kg; LYSO 56.73 ± 2.33 kg). Interestingly, total dry matter intake was not associated with LYSO despite improved average daily gain (total dry matter intake control 1,088.7 ± 27.62 g; total dry matter intake LYSO 1,124.8 ± 27.62 g). Blood glucose, albumin, creatinine, triglycerides, and cholesterol were not associated with LYSO. Indeed, only total serum protein had a significant interaction with LYSO and age at wk 5 and 6. Moreover, control calves had a 13.57 (95% confidence interval: 9.25–19.90) times greater odds of having an abnormal fecal score on any given day during the diarrhea risk period from d 1 to 28. The inclusion of LYSO as an additive in milk replacer in a dose of 4 g/d may improve performance, and calf fecal score, preweaning. Further research should investigate the mechanisms behind the effects of LYSO on fat digestibility in calves fed 6 L/d of milk replacer with vegetable-sourced fat.     

Milk feeding level and starter protein content: Effects on growth performance,blood metabolites,and urinary purine derivatives of Holstein dairy calves

The objective of this study was to investigate the effects of milk allowances equal to 526 g/d as moderate (MOD) versus 790 g/d of milk dry matter as high (HI), and starter diets containing 18% or 23% crude protein (CP), on growth performance, blood metabolites, and purine derivative (PD) excretion in the urine of dairy calves. A total of 52 female Holstein dairy calves (40.8 kg of body weight) were randomly assigned to the experimental diets. The treatments were (1) moderate milk and 18% CP starter diet (MOD-18CP); (2) MOD and 23% CP starter diet (MOD-23CP); (3) high milk and 18% CP starter diet (HI-18CP); and (4) HI and 23% CP starter diet (HI-23CP). Calves had free access to a starter feed and water and were weaned on d 53 but remained in the study until d 73. Urine samples were collected during the preweaning period (for 6 consecutive days between d 35 and 40) and postweaning period (for 6 consecutive days between d 65 and 70) to investigate urinary excretion of PD. Starter feed intake, β-hydroxybutyrate (BHB), and blood urea concentrations were reduced; however, average daily gain (ADG) and blood glucose levels increased in calves fed HI before weaning compared with MOD. During the preweaning period, high milk feeding increased total urinary PD excretion but decreased it after weaning. The 23CP diet resulted in higher feed intake and ADG before weaning and higher excretion of allantoin and total excretion of PD compared with the 18CP diet. The HI-23CP treatment resulted in the greatest withers and hip heights at weaning and final measurement, as well as the highest preweaning blood insulin concentrations. In terms of rumen development, MOD-23CP showed the greatest benefits based on starter intake, blood BHB concentration, and urinary excretion of PD. Based on the higher urinary excretion of PD found in HI-fed calves before weaning, it is possible that milk feeding overestimates estimated microbial yield. The results suggest that feeding starters with a higher proportion of CP may help maintain a more balanced ratio of CP to ME during high milk feeding, to avoid protein deficiency due to low starter intake. When calves are fed a high milk allowance, urine excretion of PD may be misinterpreted as a measure of estimated microbial growth and rumen development; this should be considered during calculations of estimated microbial yield in milk-fed calves.     

Increased super-conditioning temperature of corn grain affects performance,skeletal growth,and blood metabolites in Holstein dairy calves

We aimed to evaluate the effects of feeding super-conditioned corn at different temperatures on intake, growth performance, total-tract starch digestibility, rumen fermentation, blood metabolites, and feeding behavior of dairy calves. Thirty-six Holstein female dairy calves (40 ± 1.72 kg of body weight, ± SD) were randomly assigned to 1 of the following 3 treatments: (1) ground corn (control; CON; n = 12), (2) corn super-conditioned at 75°C (T-75; n = 12), and (3) corn super-conditioned at 95°C (T-95; n = 12). Three mash starter feeds with an identical nutritional composition were blended with 5% chopped alfalfa hay and fed to individually-housed calves from d 3 to 77 of their birth. All calves were fed 4 L/d of pasteurized whole milk twice daily since d 3 to 56, followed by 2 L/d of morning feeding from d 57 to 63 of age. Calves were weaned on d 63 and remained in the study until d 77. The T-75 and T-95 diets increased total-tract starch digestibility compared with the CON diet. Dry matter intake and weaning or final BW were not affected by treatments; however, average daily gain and feed efficiency increased in calves fed T-95 in the overall period. The T-95 diet increased withers height and tended to increase hip height compared with other diets, but feeding behavior did not change throughout the experimental period. Ruminal pH decreased in calves fed the T-95 diet compared with T-75 and CON diets. The molar proportion of ruminal propionate increased, whereas the acetate-to-propionate ratio tended to decrease in calves fed the T-95 compared with CON diet. Calves fed the T-95 diet had the highest blood glucose concentration, whereas a trend for increased insulin concentration was observed in calves fed T-95 compared with other diets. In conclusion, super-conditioning temperature of corn (T-95 vs. T-75 and CON) improved the average daily gain, feed efficiency, and skeletal growth, but did not influence dry matter intake during the first 77 d of age. Finally, the total-tract starch digestibility increased, whereas ruminal pH dropped during the postweaning period as super-conditioning temperature elevated.     

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

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

Changes in rumen fermentation and bacterial community in lactating dairy cows with subacute rumen acidosis following rumen content transplantation

Rumen microbiota intervention has long been used to cure ruminal indigestion in production and has recently become a research hotspot. However, how it controls the remodeling of rumen bacterial homeostasis and the restoration of rumen fermentation in cows of subacute ruminal acidosis (SARA) remains poorly understood. This study explored changes in rumen fermentation and bacterial communities in SARA cows following rumen content transplantation (RCT). The entire experiment comprised 2 periods: the SARA induction period and the RCT period. During the SARA induction period, 12 ruminally cannulated lactating Holstein cows were selected and allocated into 2 groups at random, fed either a conventional diet [CON; n = 4; 40% concentrate, dry matter (DM) basis] or a high-grain diet (HG; n = 8; 60% concentrate, DM basis). After the SARA induction period, the RCT period began. The HG cows were randomly divided into 2 groups: the donor-recipient (DR) group and the self-recipient (SR) group, and their rumen contents were removed completely before RCT. For the DR group, cows received 70% rumen content from the CON cows, paired based on comparable body weight; for the SR group, each cow received 70% rumen content, self-derived. The results showed that nearly all rumen fermentation parameters returned to the normal levels that the cows had before SARA induction after 6 d of transplantation, regardless of RCT. The concentrations of acetate, valerate, and total volatile fatty acids (VFA) were not recovered in the SR cows, whereas all of them were recovered in the DR cows. The amplicon sequencing results indicated that both the SR and DR cows rebuild their rumen bacterial homeostasis quickly within 4 d after RCT, and the DR group showed a higher level of bacterial community diversity. At the genus level, the DR cows displayed an improved proportion of unclassified Ruminococcaceae and Saccharofermentans compared with the SR cows. Correlation analysis between the rumen bacteria and rumen fermentation suggested some potential relationships between the predominant transplantation-sensitive operational taxonomic units and VFA. Co-occurrence network analysis revealed that RCT affected only those rumen bacterial taxa that showed weak interactions with other taxa and did not affect the pivotal rumen bacteria with high levels of co-occurrence. Our findings indicate that RCT contributes to the restoration of rumen bacterial homeostasis and rumen fermentation in cows suffering from SARA without affecting the core microbiome.     

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

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