The potential interaction between body condition score at calving and dietary starch content on productive and reproductive performance of early-lactating dairy cows

Improving reproductive performance is one of the most important factors affecting the profitability of dairy herds. This study investigated the effect of feeding a high starch (HS) diet and body condition score (BCS) at calving on blood metabolites, fertility and ovarian function and milk production in Holstein dairy cows. One hundred seventy-four multiparous cows were fed common close-up and early lactation diets during the first 15 days in milk (DIM). Cows were randomly assigned to 1 of 2 experimental diets from 16 until 50 DIM (n = 87 per group); normal starch (228 g/kg diet DM; NS) or HS (270 g/kg diet DM; HS) diets. Each treatment group was further subdivided based on BCS at calving as normal BCS (BCS ⩽ 3.5; normal BCS (NBCS); n = 45) or high BCS (HBCS) (BCS ⩾ 3.75; HBCS; n = 42). A significant difference was detected for increased milk production (47.24 v. 44.55 kg/day) and decreased milk fat (33.93 v. 36.33 g/kg) in cows fed HS or NS, respectively. Plasma glucose and insulin concentrations were significantly higher in cows fed the HS compared to the NS diet. Diets significantly affected DIM at first artificial insemination (AI, 79.51 ± 3.83 v. 90.40 ± 3.83 days for cows fed HS and NS diets, respectively). High BCS groups had greater milk fat content and elevated plasma nonesterified fatty acids (NEFA), β hydroxybutyrate (BHB) and bilirubin concentrations. In general, feeding higher starch diets to normal BCS cows during the first 50 DIM improved productive and reproductive performance of early-lactating dairy cows.     

Milk production responses and rumen fermentation of dairy cows supplemented with summer brassicas

Forage brassicas, such as summer turnip (ST; Brassica rapa) and forage rape (FR; Brassica napus), are used as supplementary crops during summer. However, studies with lactating dairy cows fed these forages are limited and report inconsistent productive responses. The aim of this study was to determine dry matter intake, rumen fermentation and milk production responses of dairy cows in mid-lactation supplemented with and without summer (‘ST’ or ‘FR’) brassicas. Twelve multiparous lactating dairy cows were randomly allocated to three dietary treatments in a replicated 3 × 3 Latin square design balanced for residual effects over three 21-day periods. The control diet consisted of 16.2 kg DM of grass silage, 2.25 kg DM of commercial concentrate and 2.25 kg DM solvent-extracted soybean meal. For the other two dietary treatments, 25% of the amounts of silage and concentrates were replaced with FR or ST. The inclusion of forage brassicas had no effects on milk production (24.2 kg cow/day average) and composition (average milk fat and protein 43.2 and 33.6 g/l, respectively). Dry matter intake was 0.98 kg and 1.12 kg lower for cows supplemented with FR and ST, respectively, resulting in a greater feed conversion efficiency (1.35 kg milk/kg DM for ST and FR v. 1.27 kg milk/kg DM for the control diet). Intraruminal pH was lower for cows supplemented with ST compared to the control diet; however, it did not decrease below pH 5.8 at any time of the day. After feeding, the concentrations of total short-chain fatty acids (SCFAs) in rumen contents increased with ST supplementation compared to the control diet. Inclusion of FR in the diet increased the molar proportion of acetate (68.5 mmol/100 mmol) in total SCFA at the expense of propionate, measured 6 h after feeding of the forage. The molar proportion of butyric acid was greater with ST and FR supplementation (13.1 and 12 mmol/100 mmol, respectively) than in control cows. The estimated microbial nitrogen (N) flow was 89.1 g/day greater when supplementing FR compared to the control diet. Based on the haematological measures, the inclusion of summer brassica forages did not affect the health status of the animals. These results indicate that mid-lactation dairy cows fed brassicas are able to maintain production despite the reduced intake, probably due to improved rumen fermentation and therefore nutrient utilization.     

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.     

Effects of dietary conjugated linoleic acid on metabolic status,BW and expression of genes related to lipid metabolism in adipose tissue of dairy cows during peripartum

Conjugated linoleic acid (CLA) dietary supplementation reduces milk fat content and yield, but its effects on lipid metabolism and energy status remain controversial. The objective of this study was to investigate the effects of dietary CLA on adipose tissue (AT) mRNA abundance of genes related to lipid metabolism, plasma indicators of metabolic status, body condition score (BCS) and BW changes in dairy cows. Sixteen multiparous Holstein cows (3.2 ± 1.4 lactations, 615 ± 15 kg BW) were randomly assigned to treatments: 1) CLA; rumen-protected CLA (75 g/d) or 2) Control; equivalent amount of rumen inert fatty acid (FA) as the previous diet (78 g/d), from − 20.2 ± 3.2 (mean ± SEM) to 21 d relative to calving (d 0). Subcutaneous AT was biopsied from the tail-head region at d 21 to determine the mRNA abundance of genes related to lipid metabolism. Blood samples were collected at − 20.2 ± 3.2, 0, 7, 14 and 21 d relative to calving to determine plasma non-esterified fatty acids (NEFA), beta-hydroxybutyrate (BHBA), insulin and glucose. Conjugated linoleic acid decreased milk fat yield and milk fat content by 15 and 16%, respectively. Cows fed CLA had lower plasma NEFA and BHBA and greater glucose and insulin concentrations (P < 0.05). Mean BCS at 21 d postpartum was greater (P < 0.01; 2.89 vs 2.25), and BCS loss from the day of enrollment to 21 d postpartum was reduced (P < 0.01; − 0.13 vs − 0.64) in the CLA group. The expression of acylcoenzyme A oxidase, carnitine palmitoyltransferase 1A, hormone-sensitive lipase, β2 adrenergic receptor and acetyl-CoA carboxylase was downregulated by CLA supplementation, whereas the expression of sterol regulatory element binding protein, lipoprotein lipase and peroxisome proliferator-activated receptor gamma was upregulated (P < 0.01). In summary, CLA-supplemented cows showed signs of better metabolic status and less severe fat mobilization. Moreover, CLA increased mRNA abundance of genes related to lipogenesis and decreased mRNA abundance of genes related to FA oxidation and lipolysis in the AT of dairy cows during early lactation.     

Effects of lowering crude protein supply alone or in a combination with essential oils on productivity,rumen function and nutrient utilization in dairy cows

Lowering dietary protein concentration is known to decrease urinary nitrogen (N) losses and increase milk N efficiency in dairy cows, but it may negatively affect animal productivity. Plant-derived essential oils (EO) may alleviate these negative effects by improving the efficiency of rumen fermentation in cows fed reduced feed protein diets. The experiment was conducted to investigate the effects of lowering crude protein (CP) supply alone or in a combination with an EO product on feed intake, milk production and composition, rumen fermentation, total tract digestibility and N utilization in dairy cows. Twenty-one Holstein cows were used in a replicated 3 × 3 Latin square design experiment. Each period consisted of 14 days for adaptation and 14 days for data collection and sampling. Cows were randomly assigned to one of three experimental diets: a 165 g/kg CP diet (control), a 155 g/kg CP diet (LCP) and LCP supplemented with 35 g/day per cow EO (LCPEO). The dry matter (DM) intake was decreased by LCP and LCPEO compared with the control; there was no effect of EO on DM intake. Milk yield and composition and feed efficiency were similar among treatments. Ruminal pH, lactate, ammonia and volatile fatty acids concentrations were not affected by treatment, except increased valerate concentration by LCPEO compared with LCP. The supplementation of EO tended to decrease protozoal counts. The LCP and LCPEO increased total tract digestibility of DM and organic matter and decreased CP digestibility compared with the control. Supplementation with EO did not affect total tract digestibility of dietary nutrients compared with the control or LCP. The LCP and LCPEO decreased urinary and fecal N excretions and increased milk N efficiency; nitrogen losses were not affected by EO. In this study, lowering dietary CP by 10 g/kg decreased urinary and fecal N excretion without affecting productivity. The supplementation of EO to LCP had only minor effects on rumen fermentation and did not affect productivity, digestibility and N excretion in lactating dairy cows.     

Supplementation of antioxidant micronutrients reduces stress and improves immune function/response in periparturient dairy cows and their calves

BackgroundPeriparturient period induces stress in cows which fluctuates hormonal and metabolic function and causes immune suppression. Apart from impairing the health, production, and reproduction of cows, it also influences the well-being of newborn calves by decreasing the colostrum quality. Micronutrients are known for optimal health and production and their effects on parturition stress, immune response in both cow and its calf need to be explored.AimThe aim of this study was to see the effect of oral supplementation of micronutrients during the prepartum period on the health status of crossbred dairy cows and subsequently on their newborn calves.MethodsA total of 42 healthy multiparous cows were selected and randomly divided into five groups with seven cows in each group, i.e. control (Basal Diet, BD), VA group (BD + vitamin A, 10⁵ IU), Zn group (BD + zinc sulphate, 60 ppm), VE group (BD + vitamin E, 2500 IU), and combined supplementation (CS) group (BD + combination of VA, Zn, and VE). The supplements were offered in compounded concentrate DM (100 g) to individual cows once daily before the morning feeding and the remaining portion was incorporated in the TMR. Feeding was started one month before the expected days of calving till calving. Blood samples were collected from cows at days -15, -7, -3, 0, +3, +7, and +15 relative to the day of calving. Blood samples from newborn calves and milk samples of cows were collected at days 0, +3, +7, and +15. Milk somatic cell counts (SCC) were estimated using a cell counter. Cortisol was estimated by ELISA kit in blood and milk plasma of cows and in the blood plasma of their calves. Total immunoglobulins (Ig) were estimated in milk of cows and serum of calves using zinc sulphate turbidity method. Blood neutrophils from cows and calves were studied for phagocytic activity (PA) using nitro blue tetrazolium (NBT) assay.Data were analysed by repeated-measures two-way ANOVA using the mixed procedure of SAS, and the pairwise comparison was performed using a multiple comparison test (Tukey).ResultsCombined supplementation of micronutrients decreased (P < 0.05) maternal blood plasma (control vs. CS group, 5.98 ± 0.20 vs. 3.86 ± 0.23 ng/mL) and milk plasma (3.96 ± 0.13 vs. 2.71 ± 0.10 ng/mL) cortisol, milk SCC (3.05 ± 0.11 vs. 2.12 ± 0.10 × 10⁵ cells/mL) and increased (P < 0.05) total milk Ig concentration (18.80 ± 0.11 vs. 23.04 ± 0.57 mg/mL) and the PA of blood neutrophils (0.84 ± 0.03 vs. 1.07 ± 0.03). Similarly, lower blood cortisol concentration (9.69 ± 0.35 vs. 6.02 ± 0.18 ng/mL) and higher (P < 0.05) total Ig (23.26 ± 0.11 vs. 30.34 ± 0.70 mg/mL) and PA of blood neutrophils (0.37 ± 0.02 vs. 0.52 ± 0.02) were observed in the calves born to CS group of cows as compared to the control. Highest (P < 0.05) positive effects (lower stress levels and higher immune response) of treatment were noticed in CS group followed by VE group and then Zn group. However, VA group didn’t differ from the control group.ConclusionOur results indicate that micronutrient interventions during the prepartum period can improve the health status of dairy calves and subsequently the well-being of their calves.     

Effects of faba bean,blue lupin and rapeseed meal supplementation on nitrogen digestion and utilization of dairy cows fed grass silage-based diets

There is increasing interest in using locally produced protein supplements in dairy cow feeding. The objective of this experiment was to compare rapeseed meal (RSM), faba beans (FBs) and blue lupin seeds (BL) at isonitrogenous amounts as supplements of grass silage and cereal based diets. A control diet (CON) without protein supplement was included in the experiment. Four lactating Nordic Red cows were used in a 4 × 4 Latin Square design with four 21 d periods. The milk production increased with protein supplementation but when expressed as energy corrected milk, the response disappeared due to substantially higher milk fat concentration with CON compared to protein supplemented diets. Milk protein output increased by 8.5, 4.4 and 2.7% when RSM, FB and BL were compared to CON. The main changes in rumen fermentation were the higher propionate and lower butyrate proportion of total rumen volatile fatty acids when the protein supplemented diets were compared to CON. Protein supplementation also clearly increased the ruminal ammonia N concentration. Protein supplementation improved diet organic matter and NDF digestibility but efficiency of microbial protein synthesis per kg organic matter truly digested was not affected. Flow of microbial N was greater when FB compared to BL was fed. All protein supplements decreased the efficiency of nitrogen use in milk production. The marginal efficiency (amount of additional feed protein captured in milk protein) was 0.110, 0.062 and 0.045 for RSM, FB and BL, respectively. The current study supports the evidence that RSM is a good protein supplement for dairy cows, and this effect was at least partly mediated by the lower rumen degradability of RSM protein compared to FB and BL. The relatively small production responses to protein supplementation with simultaneous decrease in nitrogen use efficiency in milk production suggest that economic and environmental consequences of protein feeding need to be carefully considered.     

Effects of rumen-protected choline supplementation on milk production and choline supply of periparturient dairy cows

The objective of the present study was to determine the effects of rumen-protected choline (RPC) supplementation on body condition, milk production and milk choline content during the periparturient period. Thirty-two Holstein cows were allocated into two groups (RPC group - with RPC supplementation, and control group - without RPC supplementation) 28 days before the expected calving. Cows were fed the experimental diet from 21 days before expected calving until 60 days of lactation. The daily diet of the RPC group contained 100 g of RPC from 21 days before calving until calving and 200 g RPC after calving for 60 days of lactation, which provided 25 g and 50 g per day choline, respectively. Body condition was scored on days -21, 7, 35 and 60 relative to calving. Milk production was measured at every milking; milk fat, protein and choline content were determined on days 7, 35 and 60 of lactation. Body condition was not affected by RPC supplementation. Milk yield was 4.4 kg higher for the group of cows receiving supplementary choline during the 60 days experimental period and 4% fat-corrected milk production was also increased by 2.5 kg/day. Milk fat content was not altered by treatment, but fat yield was increased by 0.10 kg/day as a consequence of higher milk yield in the RPC-treated group. Milk protein content tended to increase by RPC supplementation and a 0.18 kg/day significant improvement of protein yield was detected. Milk choline content increased in both groups after calving as the lactating period advanced. However, milk choline content and choline yield were significantly higher in the RPC group than in the control group. The improved milk choline and choline yield provide evidence that some of the applied RPC escaped ruminal degradation, was absorbed from the small intestine and improved the choline supply of the cows and contributed to the changes of production variables.     

Effect of chromium methionine supplementation on lactation performance,hepatic respiratory rate and anti-oxidative capacity in early-lactating dairy cows

Chromium may regulate dairy cow metabolism; a chelated formation of chromium methionine (Cr-Met) is available to the feed industry. The objective of this study was to investigate the effect of Cr-Met supplementation on lactation performance, hepatic respiratory rate and anti-oxidative capacity in early-lactating Holstein dairy cows. 64 multiparous cows were assigned to 16 blocks based on parity and milk yield and then the four cows in a block were randomly allocated to four treatment groups with 0, 4, 8 or 16 g/d of Cr-Met per cow supplemented to a basal diet. Cows were moved from an open dry lot to a naturally ventilated tie stall barn 2 weeks before treatment to adapt to this facility, fed and milked at 0630, 1400, and 1930 h every day. The experiment lasted for 12 weeks. Milk yield and composition were recorded weekly. Dry matter intake was measured every 2 weeks for a total of six times throughout the trial. The plasma variables were measured in weeks 4, 8 and 12 of the experiment. Supplementation of Cr-Met did not affect DM intake of cows. As the supplementation of Cr-Met increased, yields of milk, fat, energy corrected milk (P < 0.01) and lactose (P = 0.01) increased in a linear manner. In terms of plasma variables, insulin concentration decreased in a linear manner with Cr-Met supplementation. As for variables relating to hepatic respiration rate, concentrations of pyruvate and NAD in the plasma were increased in quadratic manners, and lactic dehydrogenase activity was linearly increased as Cr-Met feeding levels increased. Moreover, plasma glutathione peroxidase and superoxide dismutase activity were increased in a linear manner. In conclusion, our study suggested that Cr-Met supplementation improved lactation performance of early-lactating dairy cows through enhancing antioxidant capacity and hepatic cellular respiration.     

Effects of a combination of fibrolytic and amylolytic enzymes on ruminal enzyme activities,bacterial diversity,blood profile and milk production in dairy cows

We hypothesised that adding a combination of fibrolytic and amylolytic enzymes to the diet of early-lactation dairy cows would improve rumen enzyme activity and bacterial diversity, promote energy metabolism, and benefit milk production in cows. Twenty multiparous early-lactation (90 ± 5 d) Holstein cows with similar body conditions were randomly allocated to control (CON, n = 10) and experimental (EXP, n = 10) groups in a completely randomised single-factor design. The CON was fed only a basal total mixed ration diet, and the diet of the EXP was supplemented with a combination of fibrolytic and amylolytic enzymes at 70 g/cow/d (cellulase 3 500 CU/g, xylanase 2 000 XU/g, β-glucanase 17 500 GU/g, and amylase 37 000 AU/g). The experiment lasted 28 days, with 21 days for adaptation and 7 days for sampling. Enzyme addition increased the activity levels of α-amylase and xylanase, and the ammonia-N concentration (P < 0.05) tended to increase the activity of β-glucanase (P = 0.08) in rumen fluid. However, there was no significant difference in the rumen bacterial richness and diversity, phylum (richness > 0.1%) or genus (richness > 1%) composition between the CON and EXP groups (P > 0.05). A tendency of difference was found between CON and EXP (R = 0.22, P = 0.098) in principal component analysis. Ten genera showed different abundances across the CON and EXP groups (linear discriminant analysis effect size, linear discriminant analysis > 2). EXP increased the ratio of albumin to globulin and the concentrations of total cholesterol and low-density lipoprotein cholesterol (P < 0.05) and tended to increase triglycerides (P = 0.09) in blood. Milk yield, 3.5% fat-corrected milk yield and energy-corrected milk yield increased with enzyme supplementation (P < 0.05). The production levels of milk fat and lactose increased, but the percentage of solids, not fat and protein, decreased in EXP (P < 0.05). Although the DM intake was not affected, the feed efficiency tended to increase (P = 0.07) in EXP. In conclusion, dietary supplementation with a mixture of fibrolytic and amylolytic enzymes on multiparous early-lactation dairy cows increased α-amylase and xylanase activity levels in rumen fluid, enhanced milk performance and tended to improve the feed efficiency in cows.     

Rubber seed oil and flaxseed oil supplementation alter digestion,ruminal fermentation and rumen fatty acid profile of dairy cows

Rubber seed oil (RO) that is rich in polyunsaturated fatty acids (FA) can improve milk production and milk FA profiles of dairy cows; however, the responses of digestion and ruminal fermentation to RO supplementation in vivo are still unknown. This experiment was conducted to investigate the effect of RO and flaxseed oil (FO) supplementation on nutrients digestibility, rumen fermentation parameters and rumen FA profile of dairy cows. Forty-eight mid-lactation Holstein dairy cows were randomly assigned to one of four treatments for 8 weeks, including basal diet (CON) or the basal dietary supplemented with 4% RO, 4% FO or 2% RO plus 2% FO on a DM basis. Compared with CON, dietary oil supplementation improved the total tract apparent digestibility of DM, neutral detergent fibre and ether extracts ( P < 0.05). Oil treatment groups had no effects on ruminal digesta pH value, ammonia N and microbial crude protein ( P > 0.05), whereas oil groups significantly changed the volatile fatty acid (VFA) profile by increasing the proportion of propionate whilst decreasing total VFA concentration, the proportion of acetate and the ratio of acetate to propionate ( P < 0.05). However, there were no differences in VFA proportions between the three oil groups (P > 0.05). In addition, dietary oil supplementation increased the total unsaturated FA proportion in the rumen by enhancing the proportion of trans-11 C18:1 vaccenic acid (VA), cis-9, trans-11 conjugated linoleic acid (CLA) and α-linolenic acid (ALA) ( P < 0.05). These results indicate that dietary supplementation with RO and FO could improve nutrients digestibility, ruminal fermentation and ruminal FA profile by enhancing the VA, cis-9, trans-11 CLA and ALA composition of lactating dairy cows. These findings provide a theoretical basis for the application of RO in livestock production.     

Effects of soybean oil supplementation on performance,digestion and metabolism of early lactation dairy cows fed sugarcane-based diets

Sugarcane is an important forage source for dairy cows in tropical countries. However, it provides limited digestible fiber and energy intake, and fat supplementation can be a way to increase energy density and decrease dietary, non-fiber carbohydrates concentrations. We aimed to evaluate the performance, digestion and metabolism of dairy cows in early lactation fed different concentrations of soybean oil (SBO) in sugarcane-based diets. Fourteen primiparous (545±17.2 kg of BW) and eight multiparous (629±26.7 kg BW) Holstein dairy cows were used according to a randomized block design. After calving, diets were randomly assigned to cows within the two parity groups. Diets were formulated with increasing concentrations of SBO (g/kg dry matter (DM)): control (0), low (LSBO; 15.7), medium (MSBO; 44.3) and high (HSBO; 73.4). The study was performed from calving until 84 days in milk, divided into three periods of 28 days each. Dry matter intake (DMI) was affected quadratically in response to SBO addition with the greatest and lowest values of 19.0 and 16.0 kg/day for LSBO and HSBO diets, respectively. The digestibility of potentially digestible NDF was quadratically affected by SBO with the greatest value of 623 g/kg for LSBO diet. Both milk and energy-corrected milk (ECM) production were quadratically affected by SBO inclusion, with greatest ECM values of 27.9 and 27.3 for LSBO and MSBO, respectively. Soybean oil inclusion linearly decreased milk fat concentration by 13.2% from control to HSBO. The CLA t10,c12-18:2 was observed in milk fat only for MSBO and HSBO diets. Soybean oil inclusion did not affect plasma glucose or serum concentrations of total proteins, globulins, albumin, urea nitrogen, beta-hydroxybutyrate, non-esterified fatty acids or insulin. Serum concentrations of total cholesterol, triglycerides and low-density lipoprotein increased with SBO supplementation. Soybean oil inclusion in sugarcane-based diets for early lactation dairy cows from 15.7 to 44.3 g/kg DM can improve energy intake and performance; however, at 44.3 g/kg DM milk fat concentration and ECM decreased. Soybean oil inclusion at 73.4 g/kg DM adversely affected energy intake, fiber digestion and performance of early lactation dairy cows and is not recommended.     

Effect of butaphosphan and cyanocobalamin on postpartum metabolism and milk production in dairy cows

The aim of this study was to determine the effect of butaphosphan and cyanocobalamin (BTPC) supplementation on plasma metabolites and milk production in postpartum dairy cows. A total of fifty-two Holstein cows were randomly assigned to receive either: (1) 10 ml of saline (NaCl 0.9%, control group); (2) 1000 mg of butaphosphan and 0.5 mg of cyanocobalamin (BTPC1 group); and (3) 2000 mg of butaphosphan and 1.0 mg of cyanocobalamin (BTPC2 group). All cows received injections every 5 days from calving to 20 days in milk (DIM). Blood samples were collected every 15 days from calving until 75 DIM to determine serum concentration of glucose, non-esterified fatty acids (NEFA), β-hydroxybutyrate (BHB), cholesterol, urea, calcium (Ca), phosphorus (P), magnesium (Mg), aminotransferase aspartate (AST) and γ-glutamyltransferase (GGT). The body condition score (BCS) and milk production were evaluated from calving until 90 DIM. Increasing doses of BTPC caused a linear reduction in plasma concentrations of NEFA and cholesterol. Supplementation of BTPC also reduced concentrations of BHB but it did not differ between the two treatment doses. Milk yield and milk protein had a linear increase with increasing doses of BTPC. A quadratic effect was detected for milk fat and total milk solids according to treatment dose, and BTPC1 had the lowest mean values. Concentrations of glucose, urea, P, Mg, AST, GGT, milk lactose and BCS were not affected by treatment. These results indicate that injections of BTPC during the early postpartum period can reduce NEFA and BHB concentrations and increase milk production in Holstein cows.     

Effects of hydrolysable tannin-treated grass silage on milk yield and composition,nitrogen partitioning and nitrogen isotopic discrimination in lactating dairy cows

The objective of this study was to evaluate the effects of oak tannin extract (OTE) added in forage before ensiling on dairy cows fed at 92% of their digestible protein requirements. Six multiparous lactating Holstein cows were used in a crossover design (two treatments × two periods). The control treatment (CON) was based on a diet including 50% of grass silage, whereas the experimental treatment (TAN) included grass silage sprayed with OTE (26 g/kg DM) just before baling. Milk yield (on average 24 kg fat protein corrected milk per day) was not affected, but both milk and rumen fatty acids profiles were impacted by OTE. Nitrogen intake (415 g N per cow per day) and nitrogen use efficiency (NUE; 0.25 on average) were not affected, but a shift from urine (−8% of N intake relatively to control, P = 0.06) to faecal N (+5%; P = 0.004) was observed with the TAN diet (P ≤ 0.05). Nitrogen apparent digestibility was thus reduced for TAN (−3%; P ≤ 0.05). The effect of OTE on ruminal and milk FA profiles suggests an impact on rumen microbiota. Nitrogen isotopic discrimination between animal proteins and diet (Δ¹⁵N) was evaluated as a proxy for NUE. While no differences in NUE were observed across diets, a lower Δ¹⁵N of plasma proteins was found when comparing TAN v. CON diets. This finding supports the concept that Δ¹⁵N would mainly sign the N partitioning at the metabolic level rather than the overall NUE, with the latter also being impacted by digestive processes. Our results agree with a N shift from urine to faeces, and this strategy can thus be adopted to decrease the environmental impact of ruminant protein feeding.     

Supplementing lactating dairy cows fed high-quality pasture with black wattle (Acacia mearnsii) tannin

A reduction in urinary nitrogen (N) excretion from dairy cows fed pasture containing a high N concentration in the dry matter (DM) will have environmental benefits, because losses to soil water and air by leachate and nitrous oxides (N₂O) will be reduced. Condensed tannins (CT) reduce digestion of N, and provision as a dietary additive could have nutritional benefits for production, but the amount required and the responses to different sources of CT on milk production have not been defined. Two experiments were conducted to evaluate effects of supplementation with CT extracted from black wattle (Acacia mearnsii De Wild.) on milk production and faecal N concentration by lactating dairy cows grazing a vegetative Perennial ryegrass (Lolium perenne L.)-based pasture. In one experiment, CT was administered as a drench, twice daily, to 38 multiparous Holstein–Friesian cows assigned to four treatments; control (CONT, 0 g/day), low CT (LCT, 111 g/day), medium CT (MCT, 222 g/day) and high CT (HCT, 444 g/day), grazing as a single group. The CT supplementation affected milk yield (P < 0.001) with a trend of declining milk yield as CT concentration increased from about 0.6 to about 2.9% of dietary DM. Milk urea nitrogen (MUN) decreased at MCT and HCT levels of supplementation (P < 0.01) but milk fat, CP and lactose percentage were not affected by CT supplementation. The CT supplementation increased N concentration in faeces for LCT and MCT treatments (P < 0.05), suggesting partitioning of dietary N away from urine. When CT was pelleted with grain, in a second experiment and fed twice daily as a supplement at milking, it reduced the acceptability relative to pellets without CT, and tended to lower milk production from 25.4 to 24.5 kg/day, although the decline was not significant (P > 0.05). The diet of cows fed pellets with CT contained about 1.2% CT in the DM but neither milk constituents nor MUN were affected by CT-supplemented grain (P > 0.05). These findings demonstrate beneficial effects for production of low concentrations (c. 0.6% DM) of CT from black wattle when given to cows grazing pasture with an N concentration of 3.8%, and suggest a diversion of N from urine, but when CT exceeded about 1.4% of dietary DM, milk production was depressed. The value of supplementing a pasture diet for lactating dairy cows with black wattle tannin extract will depend on costs of supplementation, returns from milk production and liabilities associated with N losses to urine.     

Effect of substituting wet corn gluten feed and corn stover for alfalfa hay in total mixed ration silage on lactation performance in dairy cows

Wet corn gluten feed (WCGF) is a high moisture feed containing rapidly digestible, non-forage fiber and protein. The objective of this study was to investigate the effect of substituting WCGF and corn stover for alfalfa hay in total mixed ration (TMR) silage on lactation performance and nitrogen balance in dairy cows. Nine multiparous Holstein dairy cows (BW = 532 ± 28.9 kg and day in milk = 136 ± 5.6 d; mean ± SD) were used in a replicated 3 × 3 Latin square design with 21-d periods (14 d of diet adaption and 7 d of sample collection). Groups were balanced for parity, day in milk, and milk production and consumed one of three treatment diets during each period. The treatment diets were fed as TMR and contained similar concentrate mixtures and corn silage but different proportions of roughage and WCGF. The three treatments were: (1) 0% WCGF, 0% corn stover, and 22.1% alfalfa hay (0% WCGF); (2) 6.9% WCGF, 3.4% corn stover, and 11.8% alfalfa hay (7% WCGF); and (3) 13.3% WCGF, 4.9% corn stover, and 3.9% alfalfa hay (13.3% WCGF). Compared to the 0% WCGF diet, the cows fed the 7% and 13.3% WCGF diets had a higher milk yield and concentration of milk fat, protein, lactose, and total solids. Effective degradability of DM was higher in the cows fed the 7% and 13.3% WCGF diets than it was with the 0% WCGF diet. Cows fed the 13.3% WCGF had a higher CP effective degradability and a lower rumen undegraded protein than cows fed the 0% WCGF diet. The concentration of ruminal volatile fatty acids and ammonia-N was higher in cows fed the 7% and 13.3% WCGF diets than cows fed the 0% WCGF diet. The fecal N was lower in cows fed the 7% and 13.3% WCGF diets than it was in cows fed the 0% WCGF diet. Milk N secretion and milk N as a percent of N intake were higher in cows fed the 13.3% WCGF diet than cows fed the 0% and 7% WCGF diets. In conclusion, it appears that feeding a TMR silage containing WCGF and corn stover in combination, replacing a portion of alfalfa hay, may improve lactation performance and nitrogen utilization for lactating dairy cows.     

Lactational performance,feeding behavior,ruminal fermentation and nutrient digestibility in dairy cows fed whole-plant faba bean silage-based diet with fibrolytic enzyme

Whole-plant faba bean silage has a high content in indigestible fiber. Improvement of fiber digestibility of faba bean silage would benefit animal production. However, there is no study on pretreating fibrolytic enzyme in whole-plant faba bean silage-based diet for dairy cows on animal performance. The objectives of this study were to evaluate the effects of pretreating whole-plant faba bean silage-baseddiet with fibrolytic enzyme (a mixture of xylanase and cellulase; AB Vista, UK) derived from Trichoderma reesei (FETR) on lactational performance, digestibility, ruminal fermentation characteristics, and feeding behavior of dairy cows. The animal trial was conducted using eight lactating Holstein cows (BW = 710 ± 44 kg and Days in Milk (DIM) = 121 ± 17 days) with four levels of FETR (0, 0.5, 0.75, and 1.0 mL of FETR/kg DM of silage) in a replicated Latin square design. These enzyme treatments were selected based on the previous in situ and in vitro findings that showed positive responses to the whole-plant faba bean silage. The enzyme treatments were directly applied on the silage prior to mixing process. The total mixed rations contained 31% of faba bean silage, 14% of grass hay, 3.5% of straw, 30% of barley and corn grain and 21.5% of concentrate. There was no significant difference of applying FETR on nutrient intake (P > 0.05) except for CP intake, which was reduced in FETR group compared to control (P < 0.01, 4.4 vs 4.54 kg/d). There was a linear effect found in NDF digestibility when treated with FETR, where maximum improvement was achieved with 0.5 mL of FETR application. The milk fat yield, percentage of milk fat and fat-corrected milk were linearly affected by the increasing level of enzyme. The cows fed a diet supplemented with enzymes tended to have a lower milk fat. Feed efficiency linearly responded to incremental levels of FETR. There was no enzyme effect on feeding behavior and nitrogen balance and utilization. Results from this study indicated that supplementing fibrolytic enzyme on whole-plant faba bean silage diets for dairy cows improved lactational performance, intake and digestibility with 0.5 mL of FETR application. However, adding higher enzyme level resulted in negative effects on animal performance.     

Effect of farm and simulated laboratory cold environmental conditions on the performance and physiological responses of lactating dairy cows supplemented with bovine somatotropin (BST)

A study was conducted to evaluate the effect of bovine somatotropin (BST) supplementation in twelve lactating dairy cows maintained in cold environmental conditions. Six cows were injected daily with 25 mg of BST; the other six were injected with a control vehicle. Cows were maintained under standard dairy management during mid-winter for 30 days. Milk production was recorded twice daily, and blood samples were taken weekly. Animals were then transferred to environmentally controlled chambers and exposed to cycling thermoneutral (15° to 20° C) and cycling cold (–5° to +5° C) temperatures for 10 days in a split-reversal design. Milk production, feed and water intake, body weights and rectal temperatures were monitored. Blood samples were taken on days 1, 3, 5, 8 and 10 of each period and analyzed for plasma triiodothyronine (T³), thyroxine (T⁴), cortisol, insulin and prolactin. Under farm conditions, BST-treated cows produced 11% more milk than control-treated cows and in environmentally controlled chambers produced 17.4% more milk. No differences due to BST in feed or water intake, body weights or rectal temperatures were found under laboratory conditions. Plasma T³ and insulin increased due to BST treatment while no effect was found on cortisol, prolactin or T⁴. The results showed that the benefits of BST supplementation in lactating dairy cows were achieved under cold environmental conditions.     

Saturated fat supplemented in the form of triglycerides decreased digestibility and reduced performance of dairy cows as compared to calcium salt of fatty acids

The two most popular rumen-protected fatty acid supplements in dairy cow rations are calcium salts of palm oil fatty acid calcium salts of palm oil fatty acid (CSFA) and prilled saturated fatty acids (SFAs). The objectives of this study were to determine the effects of supplementing SFA in the form of triglycerides (TSFA), as compared to CSFA, on yields, efficiency and diet digestibility in high-yielding dairy cows. Twenty-eight (14 cows in each group) multiparous cows were fed a basal diet supplemented (on DM basis) with either 12 g/kg TSFA (~350 g/cow per day – contained 980 g/kg fat; 882.3 g/kg SFAs) or 14 g/kg CSFA (~440 g/cow per day – contained 800 g/kg fat; 566.4 g/kg SFAs). The supplement amounts in the diet were balanced according to fat content. Rumen samples were taken for measurements of ammonia and volatile fatty acids concentrations, and fecal samples were taken for digestibility measurements. The CSFA cows produced 3% higher milk yields (47.6 v. 46.2 kg/day; P < 0.0001) and 4.7% higher 4% fat-corrected milk (FCM; 44.7 v. 42.7 kg/day; P = 0.02) than the TSFA cows. No difference in milk-fat content was observed, but milk-protein content was higher in the TSFA than CSFA cows. Yields of fat and protein were similar, but lactose yields were higher in TSFA cows. There were no differences in dry matter intake or efficiency calculations between groups. The ruminal ammonia concentrations were similar between groups, whereas acetate concentrations and acetate : propionate ratio were greater for CSFA than TSFA cows. The apparent total-tract digestibility of dry (P < 0.0007) and organic matters (P < 0.0003), fat (P < 0.0001), NDF and ADF (P = 0.02) were lower in the TSFA v. CSFA cows. In conclusion, the CSFA-supplemented cows produced 3% higher milk and 4.7% higher 4% FCM than the TSFA cows. However, TSFA supplementation did not depress milk-protein content. The apparent total-tract digestibility was lower for all dietary components in the TSFA cows, which was probably due to the effects of both degree of saturation and triglyceride form of the TSFA supplement. Considering that diets were balanced according to the fat content of the supplements, the lower yields of milk and FCM observed in the TSFA than CSFA cows were likely due to the lower digestibility of the fat and other nutrients in the TSFA cows, which might have negatively influenced the dietary energy content.     

Odd- and branched-chain fatty acids in milk fat from Holstein dairy cows are influenced by physiological factors

Dairy products are the major source of odd- and branched-chain fatty acids (OBCFAs), a group of nutrients with emerging health benefits. The animal diet is known to influence milk fat OBCFAs of dairy cows; however, little is known about the effects of physiological factors. The objective of this study was to investigate the effects of parity and lactation stage on OBCFAs in milk fat of dairy cows. Holstein dairy cows (n = 157) were selected according to parity (first, second, third, or greater) and days in milk (DIM) (≤21 DIM, 21 < DIM ≤ 100, 100 < DIM ≤ 200, >200 DIM). All cows were fed the same total mixed ration for three weeks. Milk samples were collected during the last three days of each lactation stage for fatty acid (FA) analyses via gas chromatography. Results showed that first- and second-parity cows displayed significantly higher proportions and yields of iso-14:0, iso-15:0, iso-16:0, total iso-FA, and total branched-chain FA (P < 0.05) compared with other parities. The proportions of C17:0 and C17:1 cis-9 were also greater in first-parity cows (P < 0.05), while the yields of C17:0 and C17:1 cis-9 were similar among different parities (P > 0.05). The proportions of total OBCFAs were greater in first- and second-parity cows (P < 0.05), whereas the highest yield was observed in second-parity cows. Lactation dairy cows in ≤ 21 DIM group displayed lower proportions of iso-13:0, anteiso-13:0, C13:0, iso-14:0, C15:0, iso-16:0, total iso-FA, and total OBCFAs compared with that of the other groups (P < 0.05), and also lower yields of iso-14:0 and iso-16:0 (P < 0.05). In contrast, C17:0 and C17:1 cis-9 proportions and yields were higher in dairy cows with ≤ 21 DIM (P < 0.05). Iso-17:0 and anteiso-17:0 were not affected by lactation stage (P > 0.05). Taken together, our data showed that both parity and lactation stage have considerable effects on milk fat OBCFAs of dairy cows. In summary, first- and second-parity cows had higher milk OBCFAs compared with later parity cows, and OBCFAs with medium chain lengths were lower in dairy cows with ≤ 21 DIM, while C17:0 and C17:1 cis-9 were higher. These findings show that milk OBCFA contents are differentially modulated by physiological state. They will be useful in future studies that seek to alter OBCFA composition of Holstein dairy cow milk fats.