Effects of milk replacer powder added to pasteurized whole milk over different durations on dairy calves fed ground starter diet with alfalfa hay.

Adding milk replacer powder (MRP) to whole milk during the entire preweaning period can increase growth but raises concern because of low starter feed intake and slumps in average daily gain (ADG) at weaning and postweaning. In the current study, effects of adding MRP to pasteurized whole milk (PWM) during d 10-41 or d 10-59 of age were investigated in comparison with PWM. Calves [24 females and 21 males; 39.8 ± 1.85 kg body weight (BW)] were randomly allocated to 1 of 3 treatments: 1) conventional protocol, 5 L/d PWM from d 3-56, and 2.5 L/d from d 57-59 of age (CONV; TS intake = 31.9 kg), 2) short duration of adding MRP to PWM protocol, 5 L/d PWM from d 3-9, 5 L/d PWM + MRP (18% TS) from d 10-41, 5 L/d PWM from d 42-56, and 2.5 L/d PWM from d 57-59 (SD; TS intake = 42.3 kg), 3) long duration of adding MRP to PWM protocol, 5 L/d PWM from d 3-9, 5 L/d PWM + MRP from d 10-56, 2.5 L/d PWM + MRP form d 57-59 (LD; TS intake = 47.7 kg). The osmolality of PWM and PWM + MRP was 278 and 519 mOsm/L, respectively. Calves were weaned on d 60, and the study terminated on d 75. There was a treatment × time interaction for starter intake, where intake was greater for CONV than other treatments from d 14-41 and was greater in CONV than LD during d 42-48 and d 56-62 of age. Final BW was lower in CONV calves than LD calves. Weaning BW and overall hip height were lower in CONV calves than other treatments. The CONV calves had lower ADG at d 14-27 and 35-41 and SD calves had lower ADG at d 42-48 than other treatments. Calves fed CONV treatment had lower ruminal acetate and greater propionate than SD calves during preweaning. Calves fed LD treatment had lower total volatile fatty acids and tended to have greater ruminal pH than other treatments. Calves fed CONV had greater neutrophils and neutrophils/lymphocytes ratio and lower lymphocytes than other treatments. Glucose concentration was greater for LD versus other treatments at d 56, and lower for SD versus other treatments at d 70 of study. Insulin concentration and homeostatic model assessment of insulin resistance index were greater in LD compared with other treatments during preweaning but were not different postweaning. Serum BHB was greater in CONV than other treatments. Albumin was greater for CONV versus other treatments at d 56, however, it was greater in LD-fed calves at d 70 of study. Results indicate that feeding a PWM + MRP to the calves during the entire preweaning period resulted in lower starter feed intake around weaning, but overall starter intake was similar with a greater final BW and fewer health related issues throughout the study. Shifting a PWM + MRP to the conventional whole milk at d 40 of age decreased the ADG of calves.

Does vitamin C supplementation in milk improve growth and health of diarrheic calves?

The objective of this study was to investigate how supplementing vitamin C (VC) in milk affects growth, starter intake, blood metabolites, and the health of young calves classified into healthy or diarrheic groups. Calves were classified as diarrheic if they experienced diarrhea for at least 3 days from birth to day 7, otherwise, they were classified as healthy (i.e., days with diarrhea < 3). From day 8 of age, a total of 48 Holstein calves were divided into four groups based on a 2 × 2 factorial arrangement, with calf health status (healthy or diarrheic) and VC supplementation (VC+ or VC-) to pasteurized milk (0 or 2 g/d; 50% purity) being the main experimental factors. Calves were fed equal amounts of milk until weaning (d 60). Calves continued to be monitored until they reached 74 days of age. Calves in the VC+ group were heavier at weaning (74.3 vs. 72.2 kg; P = 0.04) compared to those calves that did not receive VC. Blood total antioxidant capacity (d 53 and 67) and superoxide dismutase activity (d 53) were greater (P < 0.01) in VC+ vs. VC- calves. Calf health status and VC supplementation interacted (P = 0.03) for blood ß-hydroxybutyrate on d 53, with the lowest concentration observed in diarrheic/VC- calves. Calves in the diarrheic group had a lower total antioxidant capacity (P = 0.01) but a greater neutrophil-to-lymphocyte ratio on d 53 and 67 (P < 0.01) than calves in the healthy group. Before weaning (d 53), neutrophil-to-lymphocyte ratio was greater, but hemoglobin was lower (P = 0.02) in calves classified into the diarrheic group that did not receive supplemental VC. The number of days medicated for diarrhea treatment was lower in VC+ calves than those in VC- group (1.73 vs. 2.47 days; P = 0.05). Overall, VC supplementation in pasteurized milk improved calf growth and health. Calves that experienced elevated episodes of diarrhea within the first week of life benefited more from supplemental VC than those classified into the healthy group.

Effects of complete substitution of dietary grain and protein sources with by-products on the production performance of mid-lactation dairy cows fed diets based on barley silage under heat-stress conditions.

This study evaluated the effects of replacing cereal grains and soybean meal with by-products (BY) on production performance, nutrient digestibility, ruminal fermentation, nutrient recovery, and eating and chewing behavior of moderate-producing dairy cows under heat-stress conditions. Twelve multiparous Holstein cows (116.7 ± 12.01 d in milk; 42.7 ± 5.06 kg/d milk yield; 665 ± 77 kg body weight; mean ± SD) were used in a replicated 3 × 3 Latin square with 28-d periods (21 d for diet adaptation and 7 d for sampling and data collection). Cows were fed a total mixed ration containing a 39.2:60.8 ratio of forage to concentrate throughout the experiment. All diets were formulated to be isoenergetic and isonitrogenous, with different concentrates. Diets were (1) control diet based on cereal grains (CON: ground corn and ground barley, plus soybean meal); (2) sugar-rich BY diet (S-BY-CM: beet pulp, citrus pulp, and liquid molasses, plus canola meal); and (3) cereal grain BY diet (CG-BY: rice bran, corn germ meal, wheat bran, barley sprout, and broken corn). Our results showed that replacing grains with BY increased neutral detergent fiber intake and digestibility but decreased starch intake, human-edible energy, and human-edible protein. Milk yield and dry matter intake (DMI) decreased more in cows fed the CG-BY diet compared with the other 2 treatments. In contrast, no significant differences were observed between the CON and S-BY-CM diets in terms of milk yield and DMI. The S-BY-CM diet increased energy-corrected milk production compared with the CG-BY diet (36.2 vs. 34.3 kg/d), but CG-BY enhanced feed conversion efficiency compared with the other 2 treatments. Although the S-BY-CM diet prolonged the eating and sorting of small particles, neither of the dietary treatments affected chewing activity or ruminal pH 4 h after feeding. Furthermore, both diets containing BY contributed to an increase in milk fat content in comparison to the CON group. Additionally, the CG-BY and S-BY-CM diets demonstrated better performance than the CON diet in terms of human-edible feed conversion efficiency for protein and energy. The results indicated that S-BY-CM can completely replace barley and corn grain in the diet of mid-lactating dairy cows exposed to heat-stress conditions without any negative effect on production and ruminal pH. However, the inclusion of CG-BY did impair DMI, milk yield, and digestibility of nutrients and is not recommended during heat-stress conditions.

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.

Impact of corn processing and weaning age on calf performance, blood metabolites, rumen fermentation, and behavior.

This study examined the impact of two corn processing methods (steam-flaked (SFC) vs. ground) combined with two weaning ages (50 or 75 days) on calf performance, blood metabolites, rumen fermentation, nutrient digestion, and behavior. The study involved 48 three-day-old Holstein calves, with an average body weight of 41.4 ± 2.2 kg. The experimental design was a 2 × 2 factorial arrangement, resulting in four treatment groups: SFC50 (SFC and weaning at 50 days), SFC75 (SFC and weaning at 75 days), GC50 (ground corn and weaning at 50 days), and GC75 (ground corn and weaning at 75 days). Calves were given whole milk at 4 L/ day from day 3-15 and 7 L/ day from day 16 to either 43 or 68, depending on weaning age. Weaning occurred between days 44 and 50 for early-weaned calves and between days 69 and 75 for late-weaned calves. The study lasted until calves were 93 days old. The starter ration consisted of soybean meal, corn grain, 5% chopped wheat straw and premix. Results indicated that the SFC-based starter feed improved calf performance and nutrient digestion, as evidenced by increased weight gain, dry matter, crude protein, and neutral detergent fiber digestibility. Calves fed the SFC-based starter diet had lower blood albumin and urea N concentrations, while blood total protein and globulin concentrations were higher, especially in early-weaned calves. No significant changes in rumen pH and ammonia-N concentration were observed. In addition, the SFC starter feed resulted in higher volatile fatty acids concentration and longer feeding time in weaned calves compared to ground corn. Overall, these results suggest that an SFC-based starter feed may be beneficial for both early and late weaned calves.

Trace minerals source in calf starters interacts with birth weights to affect growth performance.

The present study was conducted to investigate the effects of partial replacement of inorganic minerals (IM) with trace minerals in advance chelate components form in starter diets for calves of different birth weights on performance, health, and behavior of Holstein calves. Fifty-two calves were assigned to 1 of 4 treatments in a 2 × 2 factorial arrangement with two mineral sources (IM or advanced chelated minerals (ACMS)) and two birth weights (low or normal birth weight; LBW or NBW). Calves were weaned on d 56 and remained until d 71 of the study. Results showed that NBW calves had higher feed intake, withers and hip height, larger heart girth and lower fecal score than LBW calves throughout the study. Calves receiving ACMS tended to have higher feed intake, larger hip width, lower eye and nose scores, and lower rectal temperature throughout the study than IM calves. In addition, ACMS calves had larger abdominal girths at d 56 of the study compared to IM calves. Interactions between birth weights and mineral sources for preweaning average daily gain (ADG) and weaning and final BW showed that ACMS supplementation improved ADG and BW in LBW calves. Non-nutritive oral behavior was lower in ACMS calves compared to IM calves during all periods. Overall, ACMS feeding decreased non-nutritive oral behavior and improved calf health status during the study. In addition, feeding ACMS to dairy calves with LBW increased their ADG to a similar extent as to NBW calves, suggesting an improvement in their efficiency.

Feeding corn germ instead of corn grain on the performance of Holstein dairy cows fed low-forage diet and human-edible feed conversion efficiency.

Using corn germ (CG) instead of corn grain could maintain dairy cow performance and might increase the efficiency of human food production. The primary objective of this study was to evaluate the effects of replacing corn grain with CG on the performance, nutrient intake, and digestibility of dairy cows. It also aimed to investigate the effect of CG on the efficiency of human food production in high-producing Holstein dairy cows in early lactation. Nine multiparous Holstein cows with 65.6 ± 8.5 DIM, milk yield of 55.6 ± 4.5 kg/d, and body weight of 611.3 ± 43.3 kg (mean ± SD) were used in a 3 × 3 Latin square design with 21-d periods. Treatments were (1) control treatment (CT, diet contains corn grain), (2) alternative treatment (AT, diet where corn grain was replaced with CG), and (3) balanced treatment (BT, diet where corn grain was replaced with CG but with the same energy content as CT). Control and balanced diets were isoenergetic (6.61 MJ/kg of DM); however, AT had higher energy (6.77 MJ/kg of DM). Treatments had no effect on dry and organic matter intake. NDF intake, however, was higher in CG diets compared with CT (P = 0.0001). Total-tract digestibility of DM tended to be reduced (P = 0.08), and OM digestibility was reduced (P = 0.05) by the inclusion of CG in diets. Whole and energy-corrected milk production were greater in AT compared with CT and BT (P < 0.05). Milk yield was similar in cows fed CT and BT. Treatments had no effect on milk composition or feed efficiency. Diet CT, when compared with CG diets, had lower efficiency in terms of human-edible feed conversion efficiency (HeFCE) and net food production (P < 0.05). Diet BT had greater HeFCE and net production of human-edible CP than AT (P < 0.05). Plasma BHBA, non-esterified fatty acids, and glucose concentrations were not affected by treatments, but plasma cholesterol was higher in cows that consumed CG diets (P = 0.04). The results indicate that, in high-producing early lactation dairy cows fed high concentrate diets, net food protein production can be substantially improved without lowering milk production through the reduction of dietary starch from 30.2 to 24.8% by replacing corn grain with CG.

Identification of cow-level risk factors and associations of selected blood macro-minerals at parturition with dystocia and stillbirth in Holstein dairy cows.

A deeper understanding of the risk factors for dystocia and stillbirth could help farmers make decisions about dairy cow management. The objectives of this study were to investigate cow-level risk factors associated with dystocia and stillbirth in a relatively large sample of dairy cows using multivariable linear regression models. The data consisted of 51,405 calving records of 14,546 Holstein cows from 3 dairy herds in Isfahan Province, Iran, collected between April 2011 and September 2017. To investigate the association between selected blood macro-minerals and the incidence of dystocia and stillbirth, blood samples were collected at the time of parturition from a random subset of these cows, which included 1311 animals. The incidence of dystocia and stillbirths averaged 14.7% and 4.3%, respectively. Results showed that calving year, calving season, dry period length, BCS, parity, calf sex, calf birth weight, twin status, and stillbirth were significantly associated with the incidence of dystocia. According to the Random Forest (RF) classifier, we found that dry period length, calf birth weight, and parity were the most important cow-level risk factors for the incidence of dystocia. Calving year, calving season, parity, twin status, dry period length, calf birth weight, calf sex, and dystocia were significantly associated with the incidence of stillbirths. The most important risk factors identified by the RF classifier for stillbirths were twin status, parity, dry period length, and calf birth weight. Also, interactions between the cow-level risk factors associated with dystocia and stillbirth were identified. The incidence of dystocia was associated with the interactions of twin status × calf birth weight and twin status × stillbirth. According to our analysis, the incidence of stillbirth is caused by interactions among several factors, such as twin status × length of dry period, twin status × calving season, and twin status × parity. The highest incidence of dystocia (21.3%) and stillbirths (5.4%) was observed in hypo-calcemic cows. In conclusion, twin status seems to be a determining factor for the incidence of stillbirths but not for dystocia. Finally, the results of this study may help the dairy industry make management decisions aimed at reducing dystocia and stillbirth rates.

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

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

Beet pulp substituted for corn silage and barley grain in diets fed to dairy cows in the summer months: feed intake, total-tract digestibility, and milk production.

The responses of dairy cows to the substitution of beet pulp (BP) for grain or forage are not consistent, and heat stress may affect the response of dairy cows to this substitution. The effects of substituted BP for corn silage and barley grain on feed intake, performance, and ruminal parameters were evaluated using eight multiparous Holstein cows in a duplicated 4 × 4 Latin square design with 21-day periods. Cows were in mid-lactation (45.4 ±â€¯3.6 kg/day milk production and 116 ±â€¯10 days in milk) with an average BW of 664 ±â€¯41.2 kg. Dietary treatments were as follows: 1) 0% BP (0BP, control, 38.5% barley grain, and 20.3% corn silage); 2) 12% BP (12BP, 32.5% barley grain, and 14.3% corn silage); 3) 18% BP (18BP, 29.5% barley grain, and 11.3% corn silage); and 4) 24% BP (24BP, 26.5% barley grain, and 8.3% corn silage). Cows were under mild heat stress and the average temperature-humidity index was 70.5; increasing BP caused a linear decrease in respiration rate (P < 0.01). Higher BP in the diet caused a linear increase in DM intake (P = 0.01) and NDF digestibility (P = 0.03). Dry and organic matter (OM) digestibilities tended to increase linearly with higher BP (P < 0.10). Milk yield, energy-corrected milk, protein, lactose, and fat production and content were not affected by the treatments. Increasing BP in the diet caused a linear decrease in feed efficiency and rumen ammonia (P < 0.05) and a tendency to a linear decrease in milk urea nitrogen (P < 0.10). Rumen pH and acetate to propionate ratio were not affected by the replacement. Total volatile fatty acid concentration in the rumen increased linearly with increasing the BP inclusion (P = 0.04). Acetate and butyrate (P = 0.07) proportion tended to increase, whereas propionate (P = 0.06) and isovalerate (P = 0.08) proportion tended to decrease linearly as BP was substituted for corn silage and barley grain. The results indicated that under mild heat stress condition, BP can be successfully substituted for barley grain and corn silage up to 24% of the diet without any negative effect on production and ruminal pH.

Effects of physical forms of starter and milk allowance on growth performance, ruminal fermentation, and blood metabolites of Holstein dairy calves.

A 2 × 2 factorial study was conducted to evaluate the effects of milk allowance and physical forms of starter on growth performance, ruminal fermentation, and blood metabolites of Holstein dairy calves. A total of 48 calves [40.4 ± 1.55 kg of body weight (BW), n = 12 per treatment: 6 males and 6 females] were randomly assigned to 1 of the 4 treatments: (1) calves fed low milk allowance and finely ground (FG) starter feed [low-FG; 1.47 ± 2.12-mm geometric mean particle size (GMLP)], (2) calves fed low milk allowance and textured (TS) starter feed [low-TS, includes steam-flaked grains (corn and barley) with a pelleted supplement, GMLP 4.15 ± 1.77 mm], (3) calves fed high milk allowance and FG starter feed (high-FG); and (4) calves fed high milk allowance and TS starter feed (high-TS). The starter diets were blended with 7% of chopped alfalfa hay as a proportion of diet dry matter (DM). No milk refusal was observed in any treatments, and calves on both treatments were weaned from milk by wk 8 of the study using a gradual weaning procedure. We observed no interaction between milk allowance and physical forms of starter on feed intake, average daily gain, feed efficiency, BW, and structural growth. Calves fed high milk allowance had lower starter feed intake but greater feed efficiency and overall BW compared with those fed low allowance. Total DM intake and average daily gain were not different among treatments. Regardless of the physical form of starter feed, hip height, heart girth, the molar proportion of ruminal acetate, acetate to propionate ratio, plasma cholesterol, and high-density lipoprotein were greater, but ruminal total volatile fatty acids, the molar proportion of propionate, and plasma ß-hydroxybutyrate were lower in calves fed high milk allowance compared with those fed low allowance. Regardless of the milk allowance, calves fed the FG starter feeds had greater blood urea nitrogen concentrations compared with calves fed the TS starter diets. In conclusion, both forms of the starter feeds can be used when calves are fed high milk allowance with no negative effect on their performance.

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.

Substitution of wheat straw with sugarcane bagasse in low-forage diets fed to mid-lactation dairy cows: Milk production, digestibility, and chewing behavior.

Sugarcane bagasse (SB) is a low-quality roughage source that is often plentiful during times of forage shortage. It is generally less costly compared with other conventional sources of forage. We hypothesized that SB could be used as a source of roughage for dairy cattle by replacing wheat straw (WS), another low-quality forage. This study evaluated the effects of replacing WS with SB in diets offered to mid-lactation dairy cows on milk production and fatty acid profile, intake, digestibility, chewing activity, and ruminal fermentation. Nine multiparous Holstein cows averaging (mean ± standard deviation) 105 ± 12 d in milk, 42.1 ± 2.9 kg of milk/d, and 617 ± 59 kg of body weight were used in a replicated 3 × 3 Latin square with 21-d periods. Treatments were (% of dietary dry matter, DM): (1) 0SB, diet containing 0% SB and 27% WS, (2) 9SB, diet containing 9% SB and 18% WS, and (3) 18SB, diet containing 18% SB and 9% WS. Sugarcane bagasse had greater organic matter (OM; 94.1 vs. 85.1% of DM), neutral detergent fiber (NDF; 86.2 vs. 76.4% of DM), acid detergent fiber (ADF; 62.9 vs. 45.2% of DM), and lignin (19.9 vs. 10.3% of DM) concentration, but less crude protein (CP; 2.63 vs. 3.72% of DM) concentration than WS. Sugarcane bagasse also had greater physically effective NDF (total dietary NDF multiplied by % of TMR on the 8-mm + 19-mm sieves, peNDF8; 63.2 vs. 40.6% of DM) and undegraded NDF after 288 h of incubation (uNDF288; 35.5 vs. 21.2% of DM) contents than WS. The undegraded NDF after 30 h of incubation (uNDF30) content was similar for all diets; however, peNDF8 concentration and proportion of long particles (retained on a 19-mm sieve) increased linearly as SB inclusion in the diets increased. Cows increasingly sorted against long particles as SB replaced WS. Intakes of DM (26.53 kg/d) and NDF (8.58 kg/d) did not differ among the treatments, but intakes of OM and CP decreased, whereas ADF and uNDF288 intakes increased with SB inclusion level. Total-tract digestibilities of OM, CP, and NDF decreased linearly as SB replaced WS. Milk yield (37.0 kg/d), energy-corrected milk yield (ECM; 38.2 kg/d), feed efficiency (1.44 kg ECM yield/kg DM intake), and milk composition (fat, 3.89%; true protein, 2.90%) did not differ among diets. Increasing SB concentration of the diet linearly increased rumination time, but ruminal pH (ruminocentesis, 4 h after feeding) decreased. Total volatile fatty acid concentration increased linearly, whereas acetate:propionate decreased linearly, as SB replaced WS. The results indicate that replacement of WS with increasing levels of SB in low-forage diets with similar uNDF30 concentrations did not affect performance of mid-lactation dairy cows. We conclude that SB can be used as a fiber source in diets fed to dairy cows in mid-lactation; however, the decrease in total-tract digestibility of diets may decrease lactational performance when fed to high-producing dairy cows.

Effects of hydrolyzed cottonseed protein supplementation on performance, blood metabolites, gastrointestinal development, and intestinal microbial colonization in neonatal calves.

The objective of this study was to investigate the effects of an enzymatically hydrolyzed cottonseed protein (HCSP) as a peptide source on performance, blood metabolites, gastrointestinal development, and intestinal microbes. Forty-eight newborn Holstein calves were randomly assigned to 1 of the 4 dietary treatments including 0, 2, 4, and 6% of HCSP (dry matter basis). All calves received the same amount of pasteurized whole milk, weaned on d 56 of the experiment, and the study was concluded on d 70. Data were analyzed using PROC MIXED in SAS (SAS Institute Inc., Cary, NC) as a randomized complete block design with linear and quadratic contrasts. Results showed that increased amount of HCSP linearly decreased the starter intake during the postweaning (d 57 to 70) and overall period (d 1 to 70). In addition, when dietary HCSP increased during the overall period, average daily gain tended to linearly decrease. All skeletal growth variables also linearly decreased as dietary HCSP increased at the end of the study, except for body length, which did not differ among the treatments. Serum cortisol concentration was higher in calves supplemented with 6% of HCSP at weaning and at the end of the study. This indicates that these calves may have experienced a stressful condition compared with calves in other treatments. Total antioxidant capacity was quadratically affected by HCSP supplementation; calves fed 2 and 4% of HCSP diets had the highest total antioxidant capacity, whereas calves fed 0 and 6% HCSP diets had lower total antioxidant capacity at weaning and at end of the study. Calves supplemented with 6% HCSP had lower empty reticulo-rumen and omasum weights and rumen wall thickness compared with calves in other treatments at the end of the study. In conclusion, supplementation of HCSP at the rate of 2% of starter diet enhanced antioxidant status without any detrimental effects on the performance and metabolic status of calves, whereas greater inclusion rates impaired starter intake and growth of calves, and exposed them to a stressful status.

Performance and feeding behavior of dairy cows fed high-concentrate diets containing steam-flaked or ground corn varying in particle size.

Steam-flaked corn (SFC) and ground corn (GC) of different particle sizes were evaluated for their effects on dry matter intake (DMI), milk yield and components, chewing activity, ration sorting, ruminal fermentation, and digestibility in lactating dairy cows. Eight multiparous Holstein cows in mid-lactation (46.6 ± 3.5 kg/d milk production and 101 ± 10 d in milk) were used in a double 4 × 4 Latin square design with 21-d periods. Cows were fed diets (dry matter basis) containing 36.2% forage (alfalfa hay and corn silage), 37.4% corn grain, and 26.4% other ingredients. The corn grain was ground (coarse: 1.08 mm; medium: 0.84 mm; and fine: 0.73 mm) or steam-flaked (SFC; density = 0.40 kg/L). The dry matter proportion retained on an 8-mm sieve was greater for the SFC diet than for the GC diets. There were no treatment effects on DMI, milk yield, fat-corrected milk, energy-corrected milk, fat or lactose yield, protein or lactose content, or milk urea nitrogen concentration. However, digestibility of dry matter and organic matter were greater for fine GC and SFC than the other diets. In addition, cows fed SFC had lower total-tract starch digestibility than cows fed GC diets. Cows fed SFC tended to have lower propionate proportion (22.8 vs. 27.1 mM) and total volatile fatty acid concentration (88.6 vs. 99.8 mM) in ruminal fluid than those fed GC diets. Acetate and butyrate concentration, acetate to propionate ratio, and ruminal concentration of ammonia-nitrogen were not affected by treatments. Ruminal pH (6.46 vs. 6.01) as well as milk fat content (2.75 vs. 2.59%) and efficiencies (fat-corrected milk/DMI and energy-corrected milk/DMI) were greater for SFC than GC, regardless of its particle size. Milk fat content tended to increase linearly with increasing particle size of GC. Eating activity (min/d) tended to be less for SFC compared with GC, but rumination activity (min/d) and total chewing activity (min/d) were not affected by processing or particle size. The results of study indicate that, compared with GC, steam flaking of corn with 400 g/L density increased milk fat content and efficiency of high-producing dairy cows without any negative effect on milk yield. For GC, milk fat content tended to linearly increase and starch digestibility decreased linearly with increasing particle size.

Performance of dairy cows fed diets with similar proportions of undigested neutral detergent fiber with wheat straw substituted for alfalfa hay, corn silage, or both.

This study evaluated the effects of feeding diets that were formulated to contain similar proportions of undigested neutral detergent fiber (uNDF) from forage, with wheat straw (WS) substituted for corn silage (CS), alfalfa hay (AH), or both. The diets were fed to lactating dairy cows and intake, digestibility, blood metabolites, and milk production were examined. Thirty-two multiparous Holstein cows (body weight = 642 ± 50 kg; days in milk = 78 ± 11 d; milk production = 56 ± 6 kg/d; mean ± standard deviation) were used in a randomized block design with 6-wk periods after a 10-d covariate period. Each period consisted of 14 d of adaptation followed by 28 d of data collection. The control diet contained CS and AH as forage sources (CSAH) with 17% of dietary dry matter as uNDF after 30 h of incubation (uNDF30). Wheat straw was substituted for AH (WSCS), CS (WSAH), or both (WSCSAH) on an uNDF30 basis, and beet pulp was used to obtain similar concentrations of NDF digestibility after 30 h of incubation (NDFD30 = 44.5% of NDF) across all diets. The 4 diets also contained similar concentrations of net energy for lactation and metabolizable protein. Dry matter intake was greatest for WSCS (27.8 kg/d), followed by CSAH (25.7 kg/d), WSCSAH (25.2 kg/d), and WSAH (24.2 kg/d). However, yields of milk, 3.5% fat-corrected milk (FCM), and energy-corrected milk did not differ, resulting in higher FCM efficiency (kg of FCM yield/kg of dry matter intake) for WSAH (1.83) and WSCSAH (1.79), followed by CSAH (1.69) and WSCS (1.64). Milk protein percentage was greater for CSAH (2.84%) and WSCS (2.83%) than for WSAH (2.78%), and WSCSAH (2.81%) was intermediate. The opposite trend was observed for milk urea nitrogen, which was lower for CSAH (15.8 mg/dL), WSCS (15.8 mg/dL), and WSCSAH (17.0 mg/dL) than for WSAH (20 mg/dL). Total-tract NDF digestibility and ruminal pH were greater for diets containing WS than the diet without WS (CSAH), but digestibility of other nutrients was not affected by dietary treatments. Cows fed WSAH had less body reserves (body weight change = -13.5 kg/period) than the cows fed the other diets, whereas energy balance was greatest for those fed WSCS. The results showed that feeding high-producing dairy cows diets containing different forage sources but formulated to supply similar concentrations of uNDF30 while maintaining NDFD30, net energy for lactation, and metabolizable protein constant did not influence milk production. However, a combination of WS and CS (WSCS diet) compared with a diet with CS and AH improved feed intake, ruminal pH, total-tract NDF digestibility, and energy balance of dairy cows.

Adjusting for 30-hour undigested neutral detergent fiber in substitution of wheat straw and beet pulp for alfalfa hay and corn silage in the diet of high-producing cows.

This study examined the feeding effects of wheat straw (WS) and beet pulp (BP) substituted for corn silage (CS) and alfalfa hay (AH) based on forage 30-h undigested neutral detergent fiber (uNDF30) on lactation performance in high-producing dairy cows. Twelve multiparous (body weight = 611 ± 31 kg, days in milk = 97 ± 13; 51 ± 3 kg/d of milk; mean ± standard error) Holstein cows were used in a replicated 3 × 3 Latin square design with 28-d periods. Three treatments were established by substituting WS for CS and AH such that the concentration of forage uNDF30 in all diets was the same. The treatments were (1) 0% forage uNDF30 from WS (WS0; control), (2) 50% forage uNDF30 from WS (WS50), and (3) 100% forage uNDF30 from WS (WS100). Beet pulp was added in the straw diets to achieve similar dietary neutral detergent fiber digestibility after 30-h incubation (NDFD30). The 3 diets were similar in forage uNDF30 (14% of dry matter), total uNDF30 (∼18.5% of dry matter), and NDFD30 (approximately 42% of neutral detergent fiber). The substitution of WS and BP for AH and CS decreased the proportion of forage (40, 31, and 22.3% of dry matter) and forage neutral detergent fiber (21.2, 19.7, and 18.3% of dry matter) for WS0, WS50, and WS100, respectively, in the diet. However, the substitution linearly increased mean rumen pH (5.90, 6.09, and 6.28 for WS0, WS50, and WS100, respectively), digestibility of nutrients, and selection for long particles of diets without affecting dry matter intake. The substitution also linearly increased cholesterol and blood urea nitrogen concentration in the blood. Milk fat percentage, fat production, fat:protein ratio, and milk urea nitrogen increased linearly when treatments changed from WS0 to WS100, whereas the production of energy-corrected milk (ECM) was not affected by the treatments. Milk yield and milk protein yield were affected in a curvilinear manner and were lower in WS100 than other treatments. The efficiency of ECM production linearly increased in the diet with higher inclusion of WS and BP substitution in the diet (1.66, 1.70, and 1.72 for WS0, WS50, and WS100, respectively), but body weight, body weight change, and backfat thickness of cows were not different among treatments. In conclusion, the substitution of WS and BP for CS and AH with fixed uNDF30 improved feed efficiency and rumen pH, decreased milk and protein yield, and did not affect ECM yield.

Effects of increasing diet fermentability on intake, digestion, rumen fermentation, blood metabolites and milk production of heat-stressed dairy cows.

Heat stress is a major problem for dairy cows in hot climates, thus coping strategies are essential. This study evaluated the effects of increasing diet fermentability on intake, total tract digestibility, ruminal pH and volatile fatty acids (VFA) profile, blood metabolite profile and milk production and composition of lactating dairy cows managed under conditions of ambient heat stress. Nine multiparous cows (650 ± 56 kg BW; mean ± SD) averaging 102 ± 13 days in milk and producing 54 ± 6 kg/day were randomly assigned to a triplicate 3 × 3 Latin square. During each 21-day period, cows were offered one of three total mixed rations that varied in diet fermentability. The three levels of diet fermentability were achieved by increasing the proportion of pellets containing ground wheat and barley in the dietary DM from 11.7% (low), to 23.3% (moderate), and 35.0% (high) by replacing ground corn grain. Each period had 14 day of adaptation and 7 day of sampling. The ambient temperature-humidity index ( ≥ 72) indicated that the cows were in heat stress almost the entire duration of the study. Also, rectal temperature of cows was elevated at 39.2°C, another indication of heat stress. Increasing diet fermentability linearly decreased dry matter intake (22.8, 22.5, 21.8 kg/day for low, moderate and high, respectively; P ≤ 0.05) but increased non-fibre carbohydrate digestibility (P ≤ 0.05) and tended to increase digestibility of DM (P = 0.10) and crude protein (P = 0.06). As a result, the intake of digestible DM was not affected by the treatments. The production of 3.5% fat corrected milk (32.6, 33.7, and 31.5 kg/day) was quadratically (P ≤ 0.05) affected by diet fermentability with lower production for the high diet compared with the other two, which were similar. Rumen pH (ruminocentesis) and proportions of butyrate and isovalerate linearly decreased whereas propionate proportion linearly increased with increasing diet fermentability (P ≤ 0.05). The rumen concentration of NH3-N (11.0, 9.0, and 8.7 mg/dL) and blood concentration of urea linearly decreased with increasing diet fermentability (P ≤ 0.05). The activity of alkaline phosphatase increased (65.1, 83.2, and 84.9 U/l) and concentration of malondialdehyde decreased (2.39, 1.90 and 1.87 µmol/l) linearly with increasing diet fermentability (P ≤ 0.05), which indicated possible attenuation of the effects of oxidative stress with increasing diet fermentability. Overall, a modest increase of diet fermentability improved nitrogen metabolism, milk protein production and oxidative stress of heat-stressed dairy cows, but a further increase in diet fermentability decreased milk yield.