Comparison of two different anionic supplements and a low calcium diet fed to transition cows prepartum on DM intake, mineral homoeostasis and performance.

This study evaluates the effects of two rations with a positive dietary cation-anion difference (DCAD) and varying Ca content and two anionic diets on mineral homoeostasis and performance in early lactation cows. For this purpose, 48 pregnant dairy cows stratified for mature equivalent milk production, parity, body condition score (BCS), and BW were randomly assigned to four treatment groups and fed the following rations during the last 3 weeks of gestation: LC: low Ca (0.24% Ca, 1.14% K, DCAD: +86 mEq/kg DM), HC: high Ca (1.23% Ca, 1.17% K, DCAD: +95 mEq/kg DM), AS: Anionic salt (1.21% Ca, 1.21% K, DCAD: -112 mEq/kg DM, and SC: SoyChlor (1.28% Ca, 1.16% K, DCAD: -115 mEq/kg DM). After parturition, all animals were fed a common postpartum diet. Data were collected until 21 days in milk. Urinary pH was significantly decreased with the AS and SC treatment in comparison to the LC and HC groups. The highest prepartum DM intake (DMI) was found in the LC group, while DMI in AS cows was lowest. Postpartum, DMI was significantly greater in LC and SC cows than in animals fed the HC and AS rations. Prepartum serum concentrations of Ca, P, and Mg as well as postpartum serum concentrations of P and Mg did not differ, while postpartum Ca was lower in the HC group, especially 24 and 48 h after parturition. The greatest energy-corrected milk (ECM) yield was observed in cows fed the LC ration prepartum. Interestingly, milk protein production was lower in SC cows compared to LC, HC and AS. This study indicates that a ration containing a restricted Ca content fed prepartum is as suitable as a low DCAD diet to improve Ca balance without compromising DMI and performance.

Effects of corn grain processing and protein source on calf performance, rumen fermentation, and blood metabolites.

The objective of this study was to investigate the effects of the interaction between corn grain processing and protein source on feed intake, growth performance, rumen fermentation, and blood metabolites of dairy calves. Seventy-two 3-day-old Holstein calves with an initial weight of 39.1 ± 3.24 kg were randomly assigned (n = 12 calves (6 male and 6 female) per treatment) to a 2 × 3 factorial arrangement of treatments with the factors of physical form of the corn grain [coarsely ground (CG) and steam-flaked (SF)] and protein type [canola meal (CAN), canola meal + soybean meal (CASY), and soybean meal (SOY)] were assigned. The study showed a significant correlation between corn grain processing method and protein source on calf performance, including starter feed intake, total dry matter intake (DMI), body weight, average daily gain (ADG), and feed efficiency (FE). The CG-CAN and SF-SOY treatments resulted in the highest feed intake and DMI in the post-weaning and total period, respectively. Interestingly, corn processing did not affect feed intake, ADG, and FE, but the highest ADG was observed at SF-SOY and CG-CAN. In addition, the interaction between corn processing method and protein source improved FE in calves fed CG-CAN and SF-SOY during the preweaning period and throughout the period. Although skeletal growth parameters were unchanged, calves fed SOY and CASY had greater body length and withers height than calves fed CAN during the preweaning period. Rumen fermentation parameters were also not affected by the treatments, except that calves fed CAN had a higher molar proportion of acetate than calves fed SOY and CASY. Corn grain processing and protein source did not affect glucose, blood urea nitrogen (BUN), or ß-hydroxybutyrate (BHB) concentrations, except for the highest blood glucose level observed in the CAN treatment and the highest BUN level observed in the preweaned calves fed SOY. However, a two-way interaction was observed for BHB concentration, suggesting that ground corn grain resulted in higher BHB concentration during the preweaning and postweaning periods than steam-flaked corn. In summary, it is recommended to incorporate canola meal with ground corn or soybean meal with steam-flaked corn in calf starters to enhance calf growth.

Use of exogenous fibrolytic enzymes and probiotic in finely ground starters to improve calf performance.

The present study investigated the effects of adding wheat straw treated with exogenous fibrolytic enzymes (EFE) and a probiotic supplement to finely ground starters on growth performance, rumen fermentation, behavior, digestibility, and health of dairy calves. A total of 48 Holstein dairy calves (39.8 ± 1.67 kg body weight) were randomly assigned to one of 4 nutritional treatments (n = 12 calves per treatment). The experiment was conducted in a 2 × 2 factorial arrangement of treatments consisting of two diets with or without EFE-treated wheat straw (2 g/day/calf) and diets with or without probiotics (2 g/day/calf). All calves were weaned on day 63 and remained in the study until day 84. The addition of EFE to wheat straw had no effect on starter feed intake, increased neutral detergent fiber (NDF) digestibility and recumbency, but decreased average daily gain (ADG) after weaning (240 g/d). The addition of probiotics to the diet had no effect on starter feed intake, improved feed efficiency, ADG (150 g/d), final weight (11.3 kg), and NDF digestibility, and decreased the ratio of acetate to propionate in the rumen. The addition of probiotics to starter feed for calves could improve their growth.

Performance, structural growth, and digestibility by Holstein calves fed different amounts of milk through step-up/step-down or conventional methods.

Early life milk intake can influence the survival and future productivity of replacement heifers. The present study determined the effects of different amounts of milk through step-up/step-down or conventional feeding methods on the performance of dairy calves. Thirty-nine Holstein calves (18 male and 21 female) were used in a completely randomized design. Calves were randomly allocated to 1 of 3 treatments: (1) conventional milk feeding (CONV; 4.5 L/d of milk from d 1 to 50 and 2 L/d of milk at d 51 and 52 of the study; total milk intake = 229 L); (2) low milk intake with step-up/step-down method (L-SUSD, 4 L/d of milk from d 1 to 10, 6 L/d from d 11 to 20, 8 L/d from d 21 to 30, 6 L/d from d 31 to 40, 4 L/d from d 41 to 50, and 2 L/d milk at d 51 and 52 of the study, total milk intake = 284 L); (3) high milk intake with step-up/step-down method (H-SUSD, 6 L/d of milk from d 1 to 10, 8 L/d from d 11 to 20, 10 L/d from d 21 to 30, 8 L/d from d 31 to 40, 6 L/d from d 41 to 50, 4 L/d milk at d 51, and 2 L/d milk at d 52 of the study, total milk intake = 386 L). All calves were weaned at d 52 and followed until d 70. Performance data (every week), skeletal growth (d 52 and 70), and ruminal fermentation parameters and digestibility (d 35, 55, and 70) were analyzed as repeated measurements with PROC MIXED of SAS version 9.3 (SAS Institute Inc.). A treatment × time interaction was observed for total dry matter intake (TDMI) as follows: TDMI differed among all treatments where H-SUSD > L-SUSD > CONV from d 11 to 38 of study, greater for H-SUSD versus other treatments from d 3 to 10 and d 39 to 70 of study. Starter feed intake and average daily gain (ADG) were greater in H-SUSD calves than in CONV calves, and L-SUSD treatment was intermediate for those traits. The H-SUSD calves tended to have greater body weight (BW) and lower feed efficiency than calves fed CONV or L-SUSD treatments. The treatments did not affect structural growth parameters, except for hip width, which tended to be greater in H-SUSD calves than CONV calves. Regardless of treatments, ADG, starter feed intake, BW, and body measurements increased as calves aged, whereas feed efficiency increased from d 1 to 52 of study and decreased from d 52 to 70 of study. The treatments had no effect on digestibility, rumen parameters, or fecal score. Overall, in calves that were weaned at 52 d and fed milk 3 times daily, the high milk intake (386 L) through the SUSD method did not increase diarrhea or decrease digestibility but increased starter feed intake and ADG.

Effects of different planes of milk feeding and milk total solids concentration on growth, ruminal fermentation, health, and behavior of late weaned dairy calves during summer.

BACKGROUND: In recent years, there has been an increasing interest in using high quantities of milk or milk replacer (MR) in heat-stressed calves to alleviate the negative effects of high environmental temperatures on their performance. However, observations have indicated a decline in growth performance in the weaning and post-weaning period, which might be optimized with increasing total solids (TS) in milk and weaning age. This study aims to optimize the effects of higher quantities of milk on late weaned calves' performance by increasing TS concentration or delivery route in summer conditions. METHOD: Forty-eight newborn Holstein calves were used in a 2 × 2 factorial arrangement with the factors of pre-weaning total plane of milk (PM) intake (low vs. high) and milk TS content (12% vs. 17%). The treatments were (1) low PM (LPM) intake with 12% TS (TS intake = 45.9 kg), (2) LPM intake with 17% TS (TS intake = 65.1 kg), (3) high PM (HPM) intake with 12% TS (TS intake = 63.7 kg); and (4) HPM intake with 17% TS (TS intake = 90.3 kg). Calves were weaned at d 83, and the study was terminated at d 103 of age. Performance data (every 10 day), skeletal growth (d 80 and 100), ruminal fermentation parameters (d 48 and 91), and behavioral measurements (d 69, 70, 93 and 94) were analyzed as repeated measurements with PROC MIXED of SAS 9.4 (SAS Institute Inc., Cary, NC). RESULTS: Calves receiving HPM consumed less PMR from d 44 to 83 of age, but they had higher ADG from d 24 to 53 of age compared to those fed LPM (PM × age, P < 0.001). In addition, calves receiving milk with 17% TS had lower PMR intake from d 14 to 83 of age, but greater ADG from d 34 to 53 compared to those receiving milk with 12% TS (TS × age, P < 0.001). Calves that received HPM had greater skeletal growth parameters compared to LPM-fed calves, with a similar effect evident for calves fed milk with 17% TS compared with those fed milk with 12% TS. Calves receiving milk with 17% TS had greater fecal scores and diarrhea occurrence than those fed milk with 12% TS in HPM, but not LPM. CONCLUSIONS: Increasing PM and milk TS concentration improved growth in summer-exposed calves as demonstrated by increased pre-weaning ADG, pre- and post-weaning BW, and structural growth.

Effects of substitution of beet pulp for barley or corn in the diet of high-producing dairy cows on feeding behavior, performance, and ruminal fermentation.

This study investigated the effects of substituting beet pulp (BP) for different grains (barley or corn) in the diet of high-producing dairy cows on intake, feeding behavior, nutrient digestibility, ruminal fermentation, milk production, and feed conversion efficiency. Eight second-parity Holstein cows (62 ± 2 d in milk; milk yield = 54 ± 1.2 kg/d; body weight = 624 ± 26; all mean ± SE) were used in a replicated 4 × 4 Latin square design during 4 periods of 21 d. Cows were randomly assigned to 1 of 4 treatments that were a 2 × 2 factorial arrangement of 2 grain sources (corn or barley) and 2 levels of BP inclusion [5 or 15% of dry matter (DM)] in the diet: (1) barley-based diet with BP at 5% of dietary DM; (2) barley-based diet with BP at 15% of dietary DM; (3) corn-based diet with BP at 5% of dietary DM; and (4) corn-based diet with BP at 15% of dietary DM. The increasing amount of BP in the diet was at the expense of decreasing an equal proportion of grain (barley or corn). All diets were high in concentrates (65% of diet DM) and formulated to have similar concentrations of energy and protein. The portion of feedstuffs that is potentially able to be consumed by humans is known as human edible. Accordingly, human-edible protein (HEP) and human-edible energy (HEE) inputs were calculated according to the recommended potential human-edible fraction of each dietary ingredient, and HEP and HEE outputs were determined as the amount of gross energy and true protein in the milk. Feed conversion efficiency (FCE) for HEP and HEE were expressed as output per input of each variable, whereas FCE for the production of fat-corrected milk (FCM) and energy-corrected milk (ECM) were expressed as the amount of each variable per DM intake. Results showed that substituting BP for grain did not affect DM intake, crude protein intake, or nutrient digestibility, whereas starch intake (5.70 vs. 7.43 kg/d for the low-BP vs. high-BP diets, respectively), HEP (2.34 and 1.92 kg/d), and HEE (186 and 147 MJ of gross energy/d) decreased. Treatments did not affect sorting and chewing activities, but increasing BP in the diet increased ruminal pH at 4 h after feeding (6.20 vs. 6.39) and milk fat content (2.92 vs. 3.15%). Similarly, FCE for ECM production (1.44 vs. 1.54) as well as FCE for HEE (0.653 vs. 0.851) and HEP (0.629 vs. 0.702) were greater in high-BP diets compared with low-BP diets. The interaction of BP and grain sources significantly affected FCE for ECM production, where improvements were more evident when BP was substituted for barley than for corn. The improvement in FCE for HEE was greater when BP was substituted for barley (0.236) rather than corn (0.161). In conclusion, the substitution of BP for barley or corn grains in high-concentrate diets of high-producing cows decreased starch intake, increased ruminal pH at 4 h after feeding, and improved FCE for FCM production. Substitution for barley, rather than for corn, promoted greater FCE for ECM production and HEE.

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

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

Performance, rumen fermentation and blood metabolites of dairy calves fed starter mixtures supplemented with herbal plants, essential oils or monensin.

This study evaluated the supplementation effects of three herbal plants (thyme [THY], eucalyptus [EUC] and celery [CEL]), a commercial phytogenic additive containing essential oils (PFA-EO, Digestarom® P.E.P.) and monensin (MON) in calf starter on performance, rumen fermentation and blood metabolites during pre- (days 3-55) and post-weaning (days 56-70). Sixty-six Holstein dairy calves (3 days of age, 41.2 ± 3 kg of BW) were allocated to one of six starters supplemented with: (i) no additives (CON), (ii) MON (30 mg/kg), (iii) THY (23 g/kg), (iv) CEL (23 g/kg), (v) EUC (23 g/kg) and (vi) PFA-EO (3 g/kg). All the calves were offered starters ad libitum plus 6 L of whole milk daily. Starter intake tended to be the highest in calves fed PFA-EO and THY; intermediate in calves fed CON, MON and EUC; and the lowest in those fed CEL. Average daily gain (ADG) and feed efficiency (FE) remained unaffected by dietary treatments during the pre-weaning. During the post-weaning period, ADG and FE were greatest in calves fed EUC followed by those fed CON, MON, PFA-EO and THY, and then in those fed CEL. No differences were observed among the treatments in skeletal growth, faecal score, rumen pH or ammonia-N concentration. Compared to calves fed CON and MON, those fed the herbal plants or PFA-EO tended to recorded higher molar proportions of acetate and butyrate, and the acetate: propionate ratio. Blood malondialdehyde level did not differ among treatments, but calves on CON had the highest glucose concentration, and those fed PFA-EO recorded the highest value for ß-hydroxyl butyrate on day 70. In conclusion, the results indicate that the three herbs and PFA-EO are capable of modulating some of the rumen fermentation parameters and blood metabolites as well as eucalyptus could potentially be a better alternative to monensin for improving post-weaning performance.

Effects of rumen-degradable protein:rumen-undegradable protein ratio and corn processing on production performance, nitrogen efficiency, and feeding behavior of Holstein dairy cows.

This study was conducted to investigate the effects of the ratio of rumen-degradable protein (RDP) to rumen-undegradable protein (RUP) and corn processing method on production performance, nitrogen (N) efficiency, and feeding behavior of high-producing Holstein dairy cows. Twelve multiparous Holstein cows (second parity; milk yield = 48 ± 3 kg/d) were assigned to a replicated 4 × 4 Latin square design with a 2 × 2 factorial arrangement of treatments. Factor 1 was corn processing method [ground corn (GC) or steam flaked corn (SFC) with a flake density of about 390 g/L], and factor 2 was RDP:RUP ratio [low ratio (LR) = 60:40; high ratio (HR) = 65:35] based on crude protein (%). The crude protein concentrations were kept constant across the treatments (16.7% of DM). No significant interactions of main treatment effects occurred for lactation performance data. Cows fed 2 different RDP:RUP ratios exhibited similar dry matter intake (DMI), but those fed SFC showed decreased feed intake compared with those receiving GC (25.1 ± 0.48 vs. 26.2 ± 0.47 kg/d, respectively). Cows fed HR diets produced more milk than did those fed LR diets (44.4 ± 1.05 vs. 43.2 ± 1.05 kg/d, respectively). Milk fat content decreased but milk protein content increased in cows fed SFC compared with those fed GC. Feed efficiency (i.e., milk yield/DMI) was enhanced with increasing ratio of RDP:RUP (1.68 ± 0.04 vs. 1.74 ± 0.04 for LR and HR, respectively). Apparent N efficiency was higher in cows fed HR than in those fed LR (30.4 ± 0.61 vs. 29.2 ± 0.62, respectively). Compared with cows fed the GC-based diet, those receiving SFC exhibited lower values of N intake, N-NH3 concentration, and fecal N excretion. Cows receiving SFC-based diets spent more time ruminating (min/kg of DMI) than did those fed GC. Although these results showed no interaction effects of RDP:RUP ratio and corn processing method on performance, higher RDP:RUP ratios and ground corn can be effective feeding strategies for feed to lactating cows receiving high-concentrate diets.

Effect of different fat supplements on performance of dairy calves during cold season.

The objective of this experiment was to evaluate the effects of starter supplementation with fat sources differing in their fatty acid (FA) profile on performance of dairy calves during cold season. Sixty Holstein calves (3 d of age; 39.7 ± 3.8 kg of body weight) were randomly assigned to 1 of 5 starter diets supplemented with (1) no fat or oil source (control), (2) 3% palm fat (PLF), (3) 3% soybean oil (SBO), (4) 3% tallow (TAL), and (5) a 3.2% mixture (MIX) of PLF, SBO, and fish oil. The fat supplements were substituted for corn in the basal starter diet. Both the control and fat-supplemented diets contained similar amounts of dietary crude protein (19.4%), but the latter had a slightly higher quantity of calculated metabolizable energy (3.17 vs. 3.07 Mcal/kg) than did the former. Calves were reared outdoor in individual pens during the cold of winter with a mean ambient temperature of 5.0°C during the study period. Whole milk was offered twice daily from d 3 to 45 and once from d 46 to 49. The animals were weaned on d 50 and monitored in their individual pens until d 70. Supplementation with SBO and MIX increased both the dietary concentration and ratio of essential FA (n-6 and n-3), whereas supplementation with TAL and PLF made no change in the essential FA profile. Starter intake and average daily gain were not affected by PLF and TAL supplements, but were reduced as a result of feeding MIX. Feeding supplemental SBO did not affect starter intake, but tended to improve average daily gain and final body weight. Fat sources had no effects on body skeletal measurements, fecal score, digestibility, ruminal pH, ammonia, and total volatile FA concentrations; however, feeding MIX increased rumen molar proportion of propionate. No differences were observed in blood metabolites across the treatments during the preweaning period. Plasma concentrations of triacylglycerol and cholesterol increased when fat sources were supplemented and glucose concentration increased when SBO was supplemented during the postweaning period. Overall, addition of 3% PLF or TAL to the diet of young calves failed to improve growth performance. Although addition of SBO and MIX increased the dietary essential FA concentration, calf performance was only improved when SBO was supplemented.

Digestibility, ruminal fermentation, blood metabolites and antioxidant status in ewes supplemented with DL-methionine or hydroxy-4 (methylthio) butanoic acid isopropyl ester.

The effects of supplementing ewe diets with either DL-methionine (DL-Met) or 2-hydroxy-4 (methylthio) butanoic acid isopropyl ester (HMBi) were investigated on ruminal in situ degradability of grain and forage diets, in vivo digestibility, rumen fermentation, blood metabolites and antioxidant status. Six ruminally cannulated ewes were used in a replicated 3 × 3 Latin square design with 28-day periods. The dietary treatments were as follows: (i) no supplemental Met (control; CON), (ii) DL-Met at 1.2 g/kg DM intake and (iii) HMBi at 1.8 g/kg dry matter (DM) intake. Corn grain, barley grain and alfalfa hay were evaluated for their ruminal degradability by both in situ incubation and effective degradability measurements of DM, neutral detergent fibre (NDF) and acid detergent fibre (ADF). Compared to other treatments, HMBi supplementation increased (p < 0.05) the digestibility of organic matter, crude protein and NDF and also tended (p = 0.08) to increase the digestibility of DM and ADF. Moreover, HMBi supplementation increased (p < 0.01) total VFA concentrations, the molar proportions of valerate and iso-butyrate in the rumen. Compared to the CON treatment, DL-Met and HMBi treatments tended (p = 0.08) to increase the molar proportion of acetate but decreased (p < 0.05) ruminal ammonia-N concentration. Ewes supplemented with HMBi and DL-Met recorded greater (p < 0.05) serum concentrations of glutathione peroxidase, total antioxidant capacity and superoxide dismutase than the CON treatment. Serum concentrations of glucose, total protein, albumin, high-density lipoprotein and very low-density lipoprotein were greater (p < 0.01) and serum urea nitrogen (p < 0.05), malonyl dialdehyde and triglyceride were lower (p < 0.02) in the HMBi and DL-Met animals than in the CON ewes. The results concluded that HMBi is a very effective form of dietary Met supplementation for ewes with a positive effect on digestion, rumen fermentation and serum antioxidant function.

Growth performance, feeding behavior, and selected blood metabolites of Holstein dairy calves fed restricted amounts of milk: No interactions between sources of finely ground grain and forage provision.

The objective of this study was to investigate the effects of grain sources and forage provision on growth performance, blood metabolites, and feeding behaviors of dairy calves. Sixty 3-d-old Holstein dairy calves (42.2 ± 2.5 kg of body weight) were used in a 2 × 3 factorial arrangement with the factors being grain sources (barley and corn) and forage provision (no forage, alfalfa hay, and corn silage). Individually housed calves were randomly assigned (n = 10 calves per treatment: 5 males and 5 females) to 6 treatments: (1) barley grain (BG) without forage supplement, (2) BG with alfalfa hay (AH) supplementation, (3) BG with corn silage (CS) supplementation, (4) corn grain (CG) without forage supplement, (5) CG with AH supplementation, and (6) CG with CS supplementation. All calves had ad libitum access to water and starter feed throughout the experiment. All calves were weaned on d 49 and remained in the study until d 63. Starter feed intake and average daily gain (ADG) was greater for calves fed barley than those fed corn during the preweaning and overall periods. Calves supplemented with CS had greater final body weight and postweaning as well as overall starter feed intake than AH and non-forage-supplemented calves. During the preweaning and overall periods, feeding of CS was found to increase ADG compared with feeding AH and nonforage diets. However, feed efficiency was not affected by dietary treatments. Calves supplemented with CS spent more time ruminating compared with AH and control groups; nonnutritive oral behaviors were the greatest in non-forage-supplemented calves. Regardless of the grain sources, the rumen pH value was greater for AH calves compared with CS and non-forage-supplemented calves. Blood concentration of BHB was greater for CS-supplemented calves compared with AH and non-forage-supplemented calves. Furthermore, body length and heart girth were greater for calves fed barley compared with those fed corn, and also in forage-supplemented calves compared with non-forage-supplemented calves. These results showed no interactions between grain sources and forage provision on calf performance; however, the inclusion of CS and barley in starter diets could enhance the growth performance of Holstein calves during the transition from liquid to solid feed.

Interactions between the physical form of starter (mashed versus textured) and corn silage provision on performance, rumen fermentation, and structural growth of Holstein calves.

Introducing forage in the young calf diet during the milk-feeding period stimulates rumen development. It was hypothesized that performance in dairy calves would depend on forage provision and starter physical form such that the textured starter (TS) feed with corn silage (CS) supplementation would benefit calf performance. This study evaluates the effects of the physical form of starter diets and CS supplementation on performance, rumen fermentation characteristics, and structural growth of dairy calves. Forty-eight 3-d-old Holstein dairy calves with a mean starting BW of 42.1 kg (SD 2.4) were used in a 2 × 2 factorial arrangement with the factors dietary CS level (0 or 15% on DM basis) and physical form of starter (mashed vs. textured). Individually housed calves were randomly assigned ( = 12 calves per treatment: 6 males and 6 females) to 4 treatments: 1) a mashed starter (MS) feed with no CS (MS-NCS), 2) a MS feed with CS (MS-CS), 3) a TS feed with no CS (TS-NCS), and 4) a TS feed with CS (TS-CS). The calves had ad libitum access to water and starter throughout the study. All calves were weaned on d 56 of age and remained in the study until d 66. The interaction of the physical form of the starter and CS provision was significant ( < 0.01) for the starter intake, with the greatest intake for TS-CS treatment during the preweaning and overall periods. Regardless of the physical form of starter, starter intake, ADG, weaning BW, final BW, ruminal pH, the molar proportion of acetate, and the acetate-to-propionate ratio were greater ( < 0.01) for CS-supplemented calves compared with unsupplemented calves. No interaction ( > 0.05) was detected between the physical form of starter and CS provision with respect to the rumen fermentation parameters and body measurements. Total rumen VFA concentration and the molar proportion of propionate were greater ( < 0.01) in calves fed TS compared with MS-fed calves. In conclusion, independent of the physical form of starter, inclusion of 15% CS in starter diets improves the performance of dairy calves.

Reducing crude protein and rumen degradable protein with a constant concentration of rumen undegradable protein in the diet of dairy cows: Production performance, nutrient digestibility, nitrogen efficiency, and blood metabolites.

The goals of ruminant protein nutrition are to provide adequate amounts of RDP for optimal ruminal efficiency and to obtain the desired animal productivity with a minimum amount of dietary CP. The aim of the present study was to examine effects of decreasing dietary protein by decreasing RDP with the optimum concentration of RUP on production performance, nutrient digestibility, N retention, rumen fermentation parameters, and blood metabolites in high-producing Holstein cows in early lactation. Nine multiparous lactating cows (second parities, averaging 50 ± 12 d in milk and milk yield of 48 ± 5 kg/d) were used in a triplicate 3 × 3 Latin square design with 3 rations: 1) a total mixed ration (TMR) containing 16.4% CP (10.9% RDP based on DM), 2) a TMR containing 15.6% CP (10% RDP), and 3) a TMR containing 14.8% CP (9.3% RDP). The level of RUP was constant at 5.5% DM across the treatments. All diets were calculated to supply a postruminal lysine to methionine ratio of about 3:1. Dry matter intake, milk yield and composition, 4% fat-corrected milk, and energy-corrected milk were not significantly affected by decreasing dietary CP and RDP levels. Cows fed 16.4% CP diets had greater ( < 0.01) CP and RDP intakes, which resulted in a trend toward greater concentrations of plasma urea N compared with other treatments. Daily N intake linearly decreased ( < 0.01) with decreasing dietary CP and RDP levels, whereas the intake of RUP and fecal N excretion (g/d) did not change. Apparent digestibility of nutrients, ruminal pH, and NH-N concentration were not affected with decreasing dietary CP and RDP levels. Apparent N efficiency increased, and RDP N intake and predicted urine N output decreased with decreased concentration of dietary CP and RDP in the diets ( < 0.01). Blood metabolites were not affected by treatments. In conclusion, to improve the efficiency of N utilization by early-lactation dairy cows, 9.3% RDP in rations provides adequate protein to optimize milk production while minimizing N excretion in urine when the amounts of lysine and methionine and the lysine to methionine ratio are balanced with sufficient dietary RUP.

Effect of different alfalfa hay levels on growth performance, rumen fermentation, and structural growth of Holstein dairy calves.

Introducing forage in dairy calf diets during the preweaning period stimulates development of rumen capacity and function and gut wall integrity. It was hypothesized that calves fed alfalfa hay (AH) at greater levels (up to 25% of DM) would result in an increase in starter diet intake and growth performance. The objective of this study was to determine the effects of increasing levels of supplemental AH on growth performance, rumen fermentation, blood metabolites, and feeding behavior in intact male dairy calves. For this purpose, 45 Holstein male calves (3 d of age and 41 ± 2.5 kg of BW) were randomly assigned to 1 of the following 3 starter diets differing in their forage level: 1) diet without AH (control), 2) diet with 12.5% AH on a DM basis, and 3) diet with 25% AH on a DM basis. Supplementation of AH in the starter diets linearly increased total DMI and ADG during the postweaning ( < 0.01) and overall ( = 0.02) periods. Alfalfa hay supplementation linearly increased ( < 0.01) ruminal pH on d 35 and 70 of the study. The concentrations of total VFA ( = 0.85), acetate ( = 0.74), propionate ( = 0.93), and butyrate ( = 0.91) were not affected by treatments. Furthermore, forage supplementation tended (linearly, = 0.08) to increase the acetate to propionate ratio compared with the control calves. Blood ß-hydroxybutyrate (BHBA) concentrations in the control calves were less ( = 0.03) than in the AH-fed calves on d 70 of the study. Among all the measured variables of skeletal growth, supplementation of AH in the starter diets linearly increased heart girth ( = 0.05) and abdominal girth ( < 0.01) on d 70 of the study. These results indicate that the feed intake, feeding behavior, rumen fermentation parameters, and blood BHBA concentration may be affected by rations differing in AH level so that providing calves with 25% AH can improve calf performance.

Effects of forage offering method on performance, rumen fermentation, nutrient digestibility and nutritional behaviour in Holstein dairy calves.

The potential effect of dietary forage supplementation on the performance and rumen development in dairy calves is well established. However, limited research has been directed to the comparative effects of forage offering methods on calf performance. The objective of the present study was to determine the effects of forage provision methods (total mixed ration or free choice) on the performance, nutrient digestibility, rumen fermentation and nutritional behaviour in newborn calves. Forty-five Holstein dairy calves (3 days of age and 41 ± 2 kg of body weight) were assigned to the following three groups (n = 15): (i) starter without forage provision (CON), (ii) starter supplemented with 10% alfalfa hay (AH) as a total mixed ration (AH-TMR) and (iii) starter and AH as a free-choice provision (AH-FC) for a period of 70 days. All the calves were offered 5 l of milk/day from day 3 to 50, and 2.5 l/day from day 50 until weaning on day 56. Dry matter intake (DMI) was greater (p < 0.01) in the AH-TMR and AH-FC treatments than in the CON during the pre- and post-weaning periods. Calves fed the AH-FC diet showed the highest post-weaning DMI among the treatments. The calves receiving ad libitum forage tended (p = 0.08) to increase crude protein digestibility and overall volatile fatty acids (VFA) concentrations in the rumen. No differences were observed among the treatments at the time spent on standing, lying, eating and performing non-nutritive oral behaviours. Compared to CON calves, animals in the AH-TMR treatment spent more time (p < 0.05) ruminating. In conclusion, our data suggest that forage supplementation in both forage offering methods increased total DMI, ruminal pH and ruminating time in dairy calves. Hence, there is no benefit in the free-choice provision of AH in dairy calves.

Determining optimum age of Holstein dairy calves when adding chopped alfalfa hay to meal starter diets based on measures of growth and performance.

The present study was conducted to determine the optimum age of Holstein dairy calves for an effective inclusion of alfalfa hay (AH) in starter feed on performance, apparent digestibility and feeding behavior. A total of 40 Holstein dairy calves (20 female and 20 male) were used in a completely randomized design in which calves were randomly assigned to one of four different dietary treatments including control (CON) calves fed starter feed without any forage and three treatments consisting of the same starter feed plus 15% chopped AH fed when calves were at the 2nd (AH2), 4th (AH4) or 6th (AH6) week of age. Calves were individually housed and bedded with sand that was replaced every other day. Feed and water were available ad libitum throughout the experiment. Calves were fed milk at 10% of birth BW twice daily until d 57. The study concluded when calves were 73 days old. Starter intake was recorded daily and BW was measured weekly. Data were analyzed as a complete randomized design by MIXED procedures of SAS. Results demonstrate that calves receiving AH treatments numerically consumed more starter feed (0.62 v. 0.78, 0.71 and 0.65 kg/day for CON, AH2, AH4 and AH6, respectively) and had greater average daily gain (ADG) compared with CON (0.48 v. 0.57, 0.49 and 0.49 kg/day for CON, AH2, AH4 and AH6), although the significant difference was observed only between AH2 and CON. Among AH treatments, calves in AH2 had better performance than AH6 in several cases including starter intake, ADG. No detectable differences were observed, however, in apparent dry matter, organic matter or CP digestibility among treatments. Ruminal pH and NH3 concentrations, measured on weeks 4, 6, 8 and 10, were lower for calves fed CON compared with other treatments, with ammonia concentrations decreasing over time. Calves in the AH treatments spent more time eating and ruminating compared with CON. Calves fed CON, however, spent more time on laying down compared with other treatments. Overall, results from the present study illustrated that inclusion of alfalfa in starter feed for calves at 2 weeks of age may improve feed intake, ADG and stimulate rumination in young Holstein dairy calves. Results, however, should be viewed with caution as the number of calves per treatment was small and large calf-to-calf variation may have affected the results reported.

The effect of restricted milk feeding through conventional or step-down methods with or without forage provision in starter feed on performance of Holstein bull calves.

The objective of the current study was to examine whether step-down (STP) milk feeding method together with forage provision would improve performance, rumen fermentation, nutrient digestibility, blood metabolites, and structural growth of calves. Holstein bull calves ( = 40) were randomly assigned to 1 of 4 treatments in a completely randomized design with a 2 × 2 factorial arrangement. Treatments were 1) conventional (COV) milk feeding without forage provision (COV-NF), 2) COV milk feeding with forage provision, 3) STP milk feeding without forage provision, and 4) STP milk feeding with forage provision. Calves in the COV method ( = 20) received 5.5 L/d milk until d 56 of age followed by 2 L/d milk from d 56 to 59 of age. Calves in the STP method ( = 20) received 7 L/d milk until d 35, 4 L/d milk from d 35 to 48, and 2 L/d milk from d 50 to 59 of age. All the calves received the starter ration from d 3 of the study until d 74 of age. Forage-supplemented calves ( = 10/milk feeding method) received 15% alfalfa hay mixed with finely ground starter as a total mixed ration. All calves were weaned on d 60 of age and remained in the study until d 74. Regardless of the milk feeding method, the final BW (92.54 vs. 83.14 kg/d), starter intake (0.90 vs. 0.65 kg/d), total DMI (1.43 vs. 1.17 kg/d), and ADG (0.73 vs. 0.60 kg/d) were greater ( < 0.01) in forage-supplemented calves than those that received no forage during the preweaning, postweaning, and overall periods. Milk feeding method had no effect on ruminal pH, total VFA, acetate, or acetate:propionate ratio as well as body measurements. Ruminal pH and the molar proportions of acetate were greater ( < 0.05) in the forage-supplemented calves than those that received no forage during the pre- and postweaning periods. Regardless of forage provision, STP methods increased ( < 0.05) the postweaning numbers of monocytes and lymphocytes. Overall, there was no interaction between milk feeding methods and forage provision with respect to BW, DMI, G:F, apparent nutrient digestibility (DM, OM, and CP), and body measurements. The interaction of milk feeding method and forage provision was significant for the rumen concentration of butyrate ( < 0.05), with the highest concentration for the COV-NF treatment on d 35 of the study. In conclusion, independent of the milk feeding method, inclusion of 15% alfalfa hay in starter diets enhances the performance of dairy calves.

Rumen fermentation, blood metabolites, and growth performance of calves during transition from liquid to solid feed: Effects of dietary level and particle size of alfalfa hay.

This study evaluated the effects of particle size (PS) and dietary level of alfalfa hay (AH) on rumen fermentation parameters, blood metabolites, eating behavior, and growth performance in dairy calves during transition from liquid to solid feed. Sixty newborn dairy calves (41 ± 2.5,kg of body weight) were used in a 2 × 2 factorial arrangement with the factors dietary AH level (medium, 12.5%, or high, 25%, on DM basis) and PS (fine = 1mm or medium = 3mm, as geometric means) of AH. Hence, the dietary treatments were (1) medium level of AH with fine PS (M-FPS), (2) medium level of AH with medium PS (M-MPS), (3) high level of AH with fine PS (H-FPS), and (4) high level of AH with medium PS (H-MPS). Particle size of AH did not affect total DMI (TDMI) during the preweaning period, although TDMI was greater for calves fed MPS than in those fed FPS during the postweaning and overall periods. Calves fed MPS spent more time eating solid feed and ruminating and less time on nonnutritive oral behaviors compared with FPS calves. The dietary level of AH did not affect behavioral parameters. Average daily gain of calves was not affected by dietary treatment before weaning. During the postweaning and overall periods, average daily gain was greater in calves fed MPS than in those fed FPS at the 25% AH level, but this effect was absent with 12.5% AH. Furthermore, the rumen pH values on d 35 and 70 of the study were greater for MPS than for FPS, regardless of the dietary level of AH. Effects of AH level, PS, and their interaction did not affect blood glucose concentrations in developing calves. These results indicate that feed intake, feeding behavior, rumen fermentation parameters, and blood ß-hydroxybutyrate concentration may be affected by rations differing in forage PS; thus, providing calves with MPS can improve calf performance and reduce their nonnutritive oral behaviors.

Effects of the step-up/step-down and step-down milk feeding procedures on the performance, structural growth, and blood metabolites of Holstein dairy calves.

The objective of this study was to compare the efficacy of the step-up/step-down (SUSD) and step-down (STP) methods of milk feeding on the performance, growth parameters, blood metabolites, and health of dairy calves. For this purpose, 45 Holstein male calves (3d of age and 41 ± 3 kg of body weight) were randomly assigned to one of the following milk feeding groups: (1) conventional (CONV; 4 L/d milk from d 1 to 52, and 2 L/d milk from d 53 to 56 of the study), (2) STP (6 L/d milk from d 1 to 29, and 4 L/d milk from d 30 to 45 of the study followed by feeding 2L/d milk from d 46 to 56 of the study), and (3) SUSD (6 L/d milk from d 1 to 5, 8 L/d milk from d 6 to 15, 10 L/d milk from d 16 to 35, 8L/d milk from d 36 to 42, 6 L/d milk from d 43 to 47, 4 L/d milk from d 48 to 52 of the study followed by feeding 2 L/d milk from d 53 to 56 of the study). Calves were weaned on d 56 and followed until d 70 of the study period. Animals had ad libitum access to the same starter ration during the entire study period (d 3 to 70). Starter intake, total dry matter intake, and average daily gain were greater in the SUSD calves than those in the CONV and STP treatments during the preweaning period. The SUSD procedure was found to increase body weight during the entire study and improved body length, wither height, heart girth, hip height, and hip width on d 56 and 70 of the study compared with the STP and CONV calves. The SUSD treatment increased blood glucose concentration on d 35 compared with CONV and STP procedures. The STP group had a higher starter intake than the CONV and SUSD animals. The STP animals exhibited a higher plasma concentration of total protein and BHBA than did the SUSD animals during the preweaning period. Neither the SUSD nor the STP procedure negatively affected the fecal score. In conclusion, the SUSD milk feeding procedure was found to improve the performance of dairy calves compared with the STP and CONV procedures. However, it appears that the STP procedure induces earlier reticulo-rumen developement in dairy calves than does the SUSD procedure.