Impact of α‐amylase supplementation on energy balance and performance of high‐yielding dairy cows on moderate starch feeding

In dairy cows, exogenous α‐amylase is suggested to improve starch utilization and positively affect performance and health traits linked to energy balance and fertility. In a 1‐year feeding experiment, 421 cows were orally supplemented with α‐amylase (treatment: 12.5 g/kg dry matter (DM) addition rate to a concentrated feed) or non‐supplemented (control) on the basis of an ad libitum total mixed ration (TMR). Every cow was allocated to a high‐ (≥32 kg milk/day) or late‐lactation group (<32 kg milk/day), in which the TMR starch content was 220 ± 20.8 g/kg DM and 183 ± 24.8 g/kg DM, respectively. The energetic effect of α‐amylase supplementation seemed to be exclusively related to the high‐lactation stage (5–100 days in milk) in primiparous cows, where the daily milk yield was 32 ± 0.49 versus 31 ± 0.50 kg per cow in the treatment versus control group (P < 0.05). The pluriparous cows did not benefit from the supplementation that way. In neither primiparous nor pluriparous cows, was the milk composition, the fat‐to‐protein ratio, the somatic cell score, the backfat thickness, serum total bilirubin, β‐hydroxybutyrate and the fertility found to be systematically affected by α‐amylase supplementation.     

Herb feeding increases n−3 and n−6 fatty acids in cow milk

Most work dealing with the impact of species-rich herbage on milk fatty acid content has hitherto been carried out in alpine areas or semi-natural grasslands. The main objective of the present study was to examine the effect of herbs sown and intensively managed in a lowland sward on the concentration of n−3 and n−6 fatty acids and vitamins in cows' milk compared to clover grass and total mixed ration (TMR) feeding. Twelve cows were housed in tie-stall and randomly allocated to three diets fed ad libitum for 14 days: HERBS (mixture of fresh herbs); CLOVER (mixture of fresh white clover and ryegrass); or TMR (total mixed ration based on silage and concentrate). n−3 fatty acid (FA) content was similar between the three diets, while n−6 FA content was highest in the TMR diet. A twofold increase in n−3 FA concentration in milk was observed when feeding HERBS compared to CLOVER and TMR (0.8, 0.4 and 0.3 g/kg milk, respectively). n−6 FA concentration increased as well when feeding HERBS (1.4, 0.9 and 1.0 g/kg milk for HERBS, CLOVER and TMR, respectively). Transfer efficiency from feed to milk was doubled for n−3 FA when feeding HERBS and for transfer efficiency of n−6 FA from feed to milk an increase of 28% was observed for HERBS compared to CLOVER. Retinol content was highest in HERBS milk, while there was no difference in α-tocopherol and ß-carotene milk content between the three diets. The results thus support previous findings on the effect of herbs on the milk fatty acid profile, but it will require further research to understand the effect of herbs on n−3 and n−6 FA concentration in milk. In conclusion, milk content of polyunsaturated fatty acids (PUFA), like n−3 and n−6 FA, was significantly increased when herbs constituted the major part of the herbage, despite lower or similar dietary content of n−3 and n−6 FA in herbs compared to clover grass- and TMR diets.     

Effect of monensin and vitamin E on milk production and composition of lactating dairy cows

Feeding unsaturated oils to lactating dairy cows impair ruminal biohydrogenation (BH) of unsaturated fatty acids (USFA) and increase ruminal outflow of BH intermediates such as trans‐10, cis‐12 CLA that are considered to be potent inhibitors of milk fat synthesis. Supplementing lactating dairy cow’s rations containing plant origin oils with monensin and/or vitamin E may minimise the formation of trans‐10 isomers in the rumen, thereby preventing milk fat depression. Therefore, this study was conducted to evaluate the effects of monensin and vitamin E supplementation in the diets of lactating dairy cows containing whole cottonseed, as the main source of FA on feed intake, milk production and composition, milk fatty acid profile, efficiency of nitrogen (N) utilisation, efficiency of net energy (NE) utilisation and nutrients digestibilities. Four multiparous Holstein lactating dairy cows (86 ± 41 days in milk) were assigned to a balanced 4 × 4 Latin square design. Each experimental period lasted 21 days with a 14 days of treatment adaptation and a 7 days of data collection. The control diet was a total mixed ration (TMR) consisted of 430 g/kg forage and 570 g/kg of a concentrate mixture on dry matter (DM) basis. Cows were randomly assigned to one of the four dietary treatments including control diet (C), control diet supplemented with 150 mg of vitamin E/kg of DM (E), control diet supplemented with 24 mg of monensin/kg of DM (M) and control diet supplemented with 150 mg of vitamin E and 24 mg of monensin/kg of DM (EM). Dry matter intake (DMI) ranged from 19.1 to 19.5 kg/d and was similar among the dietary treatments. Dietary supplementation with vitamin E or monensin had no effect on milk production, milk fat, protein and lactose concentrations, efficiency of utilisation of nitrogen and net energy for lactation (NE_L). Digestibility of DM, organic matter (OM), crude protein (CP) and ether extract (EE) was not affected by the dietary treatments. Digestibility of neutral detergent fibre (NDF) was higher in cows fed with the M and EM diets in relation to those fed the C and E diets. The concentrations of C4:0, C6:0, C8:0, C10:0, C12:0, C14:0, C15:0, trans‐10‐16:1, cis‐9‐16:1, 17:0, 18:0, trans‐11‐18:1, cis‐9‐18:1, cis‐9, trans‐11 conjugated linoleic acid (CLA), trans‐10, cis‐12 CLA, and 18:3n‐3 FA in milk fat were not affected by the dietary supplementations. While feeding the M diet tended to decrease milk fat concentration of C16:0, the milk fat concentration of C18:2n‐6 FA tended to be increased. Dietary supplementation with vitamin E or monensin had no effect on milk fat concentrations of saturated, unsaturated, monounsaturated, polyunsaturated, short chain and long chain FA, but feeding the M diet numerically decreased milk fat concentration of medium chain fatty acids (MCFA). The results showed that vitamin E and/or monensin supplementations did not improve milk fat content and did not minimise the formation of trans‐10 FA isomers in the rumen when whole cottonseed was included in the diet as the main source of fatty acids.     

Lactation and digestion in dairy cows fed ensiled total mixed ration containing steam‐flaked or ground rice grain

The objective of this experiment was to investigate the effect of feeding ensiled total mixed ration (TMR) containing steam‐flaked (SF) or ground brown rice (Oryza satira L.; BR) on feed intake, lactation performance, digestion, ruminal fermentation and nitrogen (N) utilization in dairy cows. Eight multiparous Holstein cows were used in a crossover design with two dietary treatments: diets containing either SF or fine ground (FG) BR at 24% of dietary dry matter. Dietary treatment did not affect dry matter intake or milk yield and composition. The whole‐tract digestibility of organic matter and fiber decreased, and the digestibility of starch increased with the replacement of SF with FG in ensiled TMR, but these differences were small between diets. Crude protein digestibility was not different between diets. The processing method of BR did not affect ruminal pH, total volatile acid concentration, or volatile fatty acid proportion in cows. The N intake, milk N secretion, fecal and urinary N excretion and N retention were not influenced by dietary treatment. These results show that feeding ensiled TMR containing FG instead of SF reduces fiber digestibility but has little impact on lactation and N utilization when diets contained 24% on a dry matter basis.     

Effects of a Brown‐midrib corn hybrid on nutrient digestibility in wethers and on dry matter intake,performance, rumen and blood variables in dairy cows

The aim of the present trials was to determine the effect of an experimental Brown‐midrib (Bm) corn hybrid in relation to a commercial corn hybrid (Con) on digestibility in wethers and on dry matter intake (DMI), milk yield and milk composition in dairy cows. Digestibility of crude fibre (CF), neutral detergent fibre (NDFom) and acid detergent fibre (ADFom) were higher for Bm (CF Con: 57.8%; Bm: 67.2%; NDFom Con: 56.8%; Bm: 64.8%; ADFom Con: 52.0%; Bm: 63.9%), but concentration of net energy for lactation did not differ (Con: 6.4 MJ/kg DM; Bm: 6.3 MJ/kg DM). A total of 64 lactating German Holstein cows were assigned to one of the two dietary treatments Con or Bm according to milk yield, lactation number, days in milk and live weight. In Trial 1, cows were fed a total mixed ration consisting of 50% corn silage (Con or Bm) and 50% concentrate on dry matter (DM) basis. In Trial 2, the same animals were fed the respective silage for ad libitum intake and 5.3 kg of concentrate DM per animal per day. In Trial 1, DMI and milk‐fat content were decreased significantly for the Bm‐treatment (DMI Con: 22.5 kg/day; Bm: 21.5 kg/day; milk fat Con: 3.8%; Bm: 3.3%). In Trial 2, milk yield and fat‐corrected milk (FCM) were increased significantly, whereas milk‐fat% was decreased significantly (milk yield Con: 25.8 kg/day; Bm: 29.4 kg/day; FCM Con: 27.2 kg/day; Bm: 29.6 kg/day; fat Con: 4.4%; Bm: 4.0%). Diets did not influence ruminal pH or temperature. Diets, furthermore, did not influence rumination in either trial. Additional research on digestibility and rumen fermentation should, however, be carried out using dairy cows at respective intake levels as trials with wethers cannot be transferred to high‐yielding ad libitum fed cows.     

Effect of citrus pulp silage feeding on concentration of beta‐cryptoxanthin in plasma and milk of dairy cows

Citrus pulp is known to contain a functional molecule of beta‐cryptoxanthin which is one of the carotenoids showing anti‐oxidative capacity. Influences of citrus pulp silage feeding to dairy cows on beta‐cryptoxanthin concentration in plasma, other blood properties and milking performances were investigated. Four Holstein cows were fed total mixed ration (TMR) containing citrus pulp silage 20% dry matter (DM) for 2 weeks with free access to the TMR. Dry mater intake, milk production and milk components 2 weeks later were not altered compared with those of the control group without citrus pulp silage. Activities of aspartate aminotransferase, alanin aminotransferase and gamma‐glutamyltranspeptidase in plasma were not affected by feeding of citrus pulp silage. Concentrations of protein, albumin, sulfhydryl residue, ascorbic acid, thio‐barbituric acid reactive substance and urea nitrogen in plasma were also not altered by citrus pulp silage feeding. Concentration of beta‐cryptoxanthin in plasma was increased approximately 20‐fold compared with the control group (P < 0.05). Content of beta‐cryptxanthin in pooled milk fat fraction was also increased approximately three times compared with that of the control group. Feeding of TMR containing citrus pulp silage 15% DM for 30 days to eight dairy cows also increased plasma beta‐cryptoxanthin concentration 30‐fold compared with that before feeding.     

Milk Production of Dairy Cows Fed Total Mixed Rations After a Grazing Period

Twenty multiparous Holstein cows were used in a completely randomized design with repeated measures to study milk production of cows supplemented or not supplemented with concentrate when they were switched to a total mixed ration (TMR) after grazing. In one group, cows grazed an or-chardgrass/bromegrass pasture and were assigned to one of two treatments: 1) unsupplemented (U; 1 kg/d mineral mix) or 2) concentrate supplemented (CS; 1 kg corn-based concentrate/4 kg milk). Total DMI was greater (26.5 vs 22.0 kg/d), but pasture DMI was less (16.8 vs 21.2 kg/ d), for CS cows because of the substitution rate of 0.49 kg pasture/kg concentrate. Overall, CS cows had greater 3.5% fat-corrected milk (FCM) (32.9 vs 26.5 kg/d), but less milk urea N (MUN; 9.6 vs 14.7 mg/dL) and milk fat (3.13% vs 3.88%), than U cows. Milk response to supplementation averaged 1.08 kg milk/kg concentrate. Cows assigned to both treatments lost BW (-17 kg/d) and body condition score (BCS) (-0.33). At the end of the 6-wk grazing period, all cows were switched to a TMR fed in confinement for 11 wk. Overall, DMI (24.3 kg/d), 3.5% FCM (30.6 kg/d), milk fat (3.26%), milk true protein (2.87%), and MUN (12.7 mg/dL) did not differ between treatments. Cows gained BW (53 kg) and BCS (0.33). A significant treatment × time interaction was found for milk yield. During the first day of TMR feeding, milk yield was greater (30.9 vs 19.3 kg/d) for CS cows. After 10 d on a TMR, milk yields between cows that had previously been on the U or CS treatments did not differ (35.5 kg/d). When cows were switched from only pasture to a TMR, milk yield was comparable with that of cows fed CS after 10 d. Lack of carry-over effects of previous treatments and increased production suggest improvement in nutrition and the potential for greater animal well-being for cows housed in a tiestall barn and fed a nutritionally complete TMR.     

Milk fatty acid profile from cows fed with mixed rations and different access time to pastureland during early lactation

Milk fatty acid (FA) profiles were determined in Holstein cows (n = 27) fed total mixed rations (TMR) ad libitum (G0) or diet composed by TMR (50% dry matter [DM] offered) plus grazing of pasture with 6 hr of access time to paddock in one session (G1) or 9 hr in two sessions (G2) at 45 days in milk (DIM). Moreover, milk FA was determined at 65 DIM when G0 cows turned out to G1 diet without adaptation period (Post‐G0), G1 remained as controls. Milk FA was quantified using gas chromatography and mass spectrometry. Preformed FA at 45 DIM was greater (+27%) for G2 than G0 cows (p < .05). Stearic acid (C18:0) was 30% greater for G2 cows (p < .05). De novo FA was lowest for G2 cows (p < .05). Conjugated linoleic acid (CLA) did not differ (p < .12), while vaccenic acid (C18:1trans) was twofold greater for grazing treatments (p < .01). Linolenic acid [C18:3(n‐3)] was greatest for G2 and lowest for G0 cows (p < .01). Omega 6 FA was greater for G0 than grazing cows, mainly due to linoleic acid [18:2cis(n‐6); p < .05]. These results determined that n‐6/n‐3 ratio was almost threefold greater for G0 than grazing cows (p < .001). When diet of G0 cows changed to include pasture (Post‐G0), preformed FA increased (p < .05), explained mainly by the increase (p < .05) of stearic (C18:0) and C18:1trans, while de novo FA tended to decrease (p < .1). Moreover, the amount of CLA and C18:3(n‐3) tended to increase (p < .1) in Post‐G0 cows. Offering 50% of dietary DM from pasture modified milk FA profile in early lactation potentially beneficial for human health. When TMR‐fed cows were turned out to 50% pasture, milk FA profile reflected dietary change without need of an adaptation period.     

Safety of standardized Macleaya cordata extract in an eighty‐four‐day dietary study in dairy cows

The objective of this study was to evaluate the safety of a standardized Macleaya cordata Extract Product (MCEP) containing the quaternary benzophenanthridine alkaloids, sanguinarine and chelerythrine, when fed to dairy cows. Thirty‐six dairy cows were randomized into three groups with twelve cows/treatment in two replica pens for each treatment group: control (C) without MCEP added to feed, treatment 1 (SANG‐1000) with MCEP added to feed at 1,000 mg/animal/day (1.5 mg/kg bw/day) and treatment 2 (SANG‐10000) with MCEP added to feed at 10,000 mg/animal/day (15.5 mg MCEP/kg bw/day). After two weeks of acclimation, animals were observed for an 84‐day experimental period, with body weight, feed intake and milk production measured daily. Milk composition was analysed every two weeks. Haematological analyses were performed on Day 0 and Day 84, and clinical chemistry analyses were performed on Day 84 of the study. There was no statistically significant difference (p > .10) among the three groups on body condition score, milk production or milk composition over the study period. There were no significant differences in body weight gain or feed consumption among the three groups. Animals in the SANG‐10000 group had significantly higher mean corpuscular volume (MCV) than the C group (p < .1) and lower mean corpuscular haemoglobin concentration (MCHC) than the SANG‐1000 group (p < .1). Concentrations of sanguinarine and chelerythrine in milk samples collected on Day 84 were below the detection limit (LOD) as measured by high‐performance liquid chromatography‐mass spectrometry (HPLC‐MS/MS). In conclusion, this study presents compelling data supporting the hypothesis that the test product MCEP, when included in the TMR at up to 10,000 mg/animal/day (15.5 mg MCEP/kg bw/day), is well tolerated by dairy cows.     

Diet change from a system combining total mixed ration and pasture to confinement system (total mixed ration) on milk production and composition,blood biochemistry and behavior of dairy cows

This study aimed to determine if a diet change from a mixed system to a confinement system affects the milk production and composition, behavior and blood biochemistry of dairy cows. Cows were assigned randomly to one of the two treatments: cows fed with TMR (total‐mixed‐ration) (confined) throughout the period group fed TMR (GTMR, n = 15) and cows that changed their diet from pasture plus TMR to exclusive TMR at 70 ± 14 DIM (GCHD, n = 15). GTMR cows produced more milk and greater lactose and protein yield before the change of diet than GCHD cows (p ≤ .01), but these differences disappeared after the change. GCHD cows decreased the frequency of rumination and lying from before to after the change (p ≤ .03), but in GTMR cows no changes were observed. After diet change, GCHD cows had lower frequency of rumination and lying than GTMR cows (p ≤ .02). Before the change, GCHD cows had greater NEFA (non esterified fatty acids) concentrations than GTMR cows (p = .002). Abrupt change from a mixed system to a confined system was favorable on blood biochemical and milk variables of dairy cows. However, in relation to behavior, the cows expressed difficulties to adapt quickly to the abrupt change of system.     

Effect of raw soya bean particle size on productive performance and digestion of dairy cows

Differing soya bean particle sizes may affect productive performance and ruminal fermentation due to the level of fatty acid (FA) exposure of the cotyledon in soya bean grain and because the protein in small particles is more rapidly degraded than the protein in large particles, which influence ruminal fibre digestion and the amounts of ruminally undegradable nutrients. The objective of this experiment was to investigate the effects of raw soya bean particle size on productive performance, digestion and milk FA profile of dairy cows. Twelve Holstein cows were assigned to three 4 × 4 Latin squares with 21‐day periods. At the start of the experiment, cows were 121 days in milk (DIM) and yielded 30.2 kg/day of milk. Cows were fed 4 diets: (i) control diet (CO), without raw soya bean; (ii) whole raw soya bean (WRS); (iii) cracked raw soya bean in Wiley mill 4‐mm screen (CS4); and (iv) cracked raw soya bean in Wiley mill 2‐mm screen (CS2). The inclusion of soya beans (whole or cracked) was 200 g/kg on dry matter (DM) basis and partially replaced ground corn and soya bean meal. Uncorrected milk yield and composition were not influenced by experimental diets; however, fat‐corrected milk (FCM) decreased when cows were fed soya bean treatments. Soya bean diets increased the intake of ether extract (EE) and net energy of lactation (NE_L), and decreased the intake of DM and non‐fibre carbohydrate (NFC). Ruminal propionate concentration was lower in cows fed WRS than cows fed CS2 or CS4. Cows fed cracked raw soya bean presented lower nitrogen in faeces than cows fed WRS. The milk of cows fed WRS, CS2 and CS4 presented higher unsaturated FA than cows fed CO. The addition of raw soya bean in cow diets, regardless of the particle size, did not impair uncorrected milk yield and nutrient digestion, and increased the concentration of unsaturated FA in milk. Cows fed cracked raw soya bean presented similar productive performance to cows fed whole raw soya bean.     

Effect of non‐starch‐polysaccharide‐degrading enzymes as feed additive on the rumen bacterial population in non‐lactating cows quantified by real‐time PCR

The effects of non‐starch‐polysaccharide‐degrading enzymes, added to a maize silage‐ and grass silage‐based total mixed ration (TMR) at least 14 h before feeding, on the rumen bacterial population were investigated. Six non‐lactating Holstein Friesian cows were allocated to three treatment groups using a duplicate 3 × 3 Latin square design with three 31‐day periods (29 days of adaptation and 2 days of sampling). Treatments were control TMR [69% forage and 31% concentrates on a dry matter (DM) basis] or TMR with 13.8 or 27.7 ml/kg of feed DM of Roxazyme G2 liquid with activities (U/ml enzyme preparation) of xylanase 260 000, β‐glucanase 180 000 and cellulase 8000 (DSM Nutritional Products, Basel, Switzerland). The concentrations of 16S rDNA of Anaerovibrio lipolytica, Fibrobacter succinogenes, Prevotella ruminicola, Ruminococcus flavefaciens, Selenomonas ruminantium and Treponema bryantii, and their relative percentage of total bacteria in rumen samples obtained before feeding and 3 and 7 h after feeding and from two rumen fractions were determined using real‐time PCR. Sampling time had only little influence, but bacterial numbers and the composition of the population differed between the transition layer between rumen fluid and the fibre mat (fraction A) and the rumen fluid (fraction B) highlighting the importance to standardize sampling. The 16S rDNA copies of total bacteria and the six bacterial species as well as the population composition were mainly unaffected by the high levels of exogenous enzymes supplemented at all sampling times and in both rumen fractions. Occasionally, the percentages of the non‐fibrolytic species P. ruminicola and A. lipolytica changed in response to enzyme supplementation. Some increases in the potential degradability of the diet and decreases in lag time which occurred collaterally indicate that other factors than changes in numbers of non‐particle‐associated bacteria are mainly responsible for the effects of exogenous enzymes.     

Effect of replacing corn with brown rice grain in a total mixed ration silage on milk production,ruminal fermentation and nitrogen balance in lactating dairy cows

Nine multiparous Holstein cows were used in a replicated 3 × 3 Latin square design to determine the effects of substituting corn grain with brown rice (BR) grain in total mixed ration (TMR) silage on milk yield, ruminal fermentation and nitrogen (N) balance. The TMR silages were made from the ensiling of TMR containing (dry matter basis) 50.1% forage in rice silage and corn silage combination, and 49.9% concentrate. The grain portion of the diets contained 31.2% steam‐flaked corn, 31.2% steam‐flaked BR or an equal mixture of corn and BR. Dietary treatments did not affect dry matter intake, milk yield and milk fat, protein and lactose yields. The ruminal pH and total volatile fatty acid concentrations were not affected by dietary treatment. The urinary N excretion decreased linearly (P < 0.01) in response to increased levels of BR, with no dietary effect on N intake, N secretion in milk and fecal N excretion. Our results indicate that steam‐flaked BR is a suitable replacement for steam‐flaked corn in dairy cow diets, and that it can be included in rations to a level of at least 31.2% of dry matter without adverse effects on milk production, when cows were fed rice silage and corn silage‐based diets.     

Effect of wood kraft pulp feed on digestibility,ruminal characteristics,and milk production performance in lactating dairy cows

The effect of wood kraft pulp (KP) feed on dietary digestibility, ruminal fluid pH, rumen fermentation characteristics, and milk production performance in lactating dairy cows was examined. Four lactating dairy cows were used for the feeding experiment by the cross‐over design. The control group and KP group were set up as treatments. The control group was fed total mixed ration (TMR) (40% roughage and 60% concentrate) and the KP group was fed TMR containing 12% KP that replaced half of the rolled corn in the control diet. The dry matter intake, digestibility of the feed components, and milk yield were not significantly different between control group and KP group. The number of times that the ruminal fluid pH was below 6.1 tended to decrease in the KP group compared to the control group (p < 0.10). The acetic acid ratio in the ruminal fluid of the KP group increased compared to the control group (p < 0.05) and the propionic acid ratio in the ruminal fluid of the KP group decreased compared to the control group (p < 0.05). The acetate:propionate acid ratio was increased in the KP group compared with the control group (p < 0.05). Lipopolysaccharide levels in the ruminal fluid of the KP group tended to decrease compared to the control group (p < 0.10). Based on these results, it was indicated that the use of KP feed for lactating dairy cows induced the same rumen fermentation characteristics as those in cows given a large amount of roughage without depressing milk productivity. Therefore, KP could be a valuable feed resource substitute for grains, which would also reduce the risk for subacute rumen acidosis.     

Effects of feeding yeast and propionibacteria to dairy cows on milk yield and components, and reproduction*

To determine the effect of supplemental feeding of Diamond V-XP yeast (XPY) alone or in combination with propionibacteria strain P169 on milk production, milk components, body weight, days to first and second ovulation, plasma insulin, and plasma and milk glucose, 31 primiparous and multiparous (MP) Holstein cows were fed one of three dietary treatments between 2 weeks prepartum to 30 weeks postpartum: (i) control (n = 10), fed a corn silage-based total mixed ration (TMR); (ii) XPY (n = 11), fed control TMR plus XPY (at 56 g/head/day); and (iii) P169+XPY (n = 10), received control TMR plus XPY plus P169 (at 6 x 10(11) cfu/head/day). After parturition, daily milk weights were recorded, and milk samples were collected twice weekly for milk component analyses. Daily uncorrected milk, solids-corrected milk, and 4% fat-corrected milk production for MP cows fed P169+XPY was 9-16% greater than control MP cows, but these increases were only evident during mid lactation (9-30 weeks). The percentage of milk fat was 8-18% greater in control than XPY and P169+XPY groups. Milk lactose percentage in MP cows fed P169+XPY was 3-5% greater than in control and XPY MP cows. Primiparous and MP cows fed P169+XPY had 28-32% greater milk glucose levels than control and XPY-fed cows. Diurnal plasma glucose concentration was not affected by diet in MP cows. Plasma insulin levels in MP cows fed P169+XPY were 30-34% greater than in other groups of MP cows. Milk glucose and plasma insulin responses to P169+XPY feeding suggest that P169+XPY might have enhanced gluconeogenesis and increased glucose uptake by the mammary gland in Holstein cows. Thus, a combined feed supplement of P169 and XPY may hold potential as a natural feed alternative to hormones and antibiotics to enhance lactational performance.     

Sainfoin (Onobrychis viciifolia) silage in dairy cow rations reduces ruminal biohydrogenation and increases transfer efficiencies of unsaturated fatty acids from feed to milk

The effects of replacing grass silage by sainfoin silage in a total mixed ration (TMR) based diet on fatty acid (FA) reticular inflow and milk FA profile of dairy cows was investigated. The experiment followed a crossover design with 2 dietary treatments. The control diet consisted of grass silage, corn silage, concentrate and linseed. In the sainfoin diet, half of the grass silage was replaced by a sainfoin silage. Six rumen cannulated lactating multiparous dairy cows with a metabolic body weight of 132.5 ± 3.6 kg BW^0.75, 214 ± 72 d in milk and an average milk production of 23.1 ± 2.8 kg/d were used in the experiment. Cows were paired based on parity and milk production. Within pairs, cows were randomly assigned to either the control diet or the sainfoin diet for 2 experimental periods (29 d per period). In each period, the first 21 d, cows were housed individually in tie-stalls for adaptation, then next 4 d cows were housed individually in climate-controlled respiration chambers to measure CH₄. During the last 4 d, cows were housed individually in tie stalls to measure milk FA profile and determine FA reticular inflow using the reticular sampling technique with Cr-ethylenediaminetetraacetic acid disodium salt dihydrate (EDTA) and Yb-acetate used as digesta flow markers. Although the dietary C18:3n-3 intake was lower (P = 0.025) in the sainfoin diet group, the mono-unsaturated FA reticular inflow was greater (P = 0.042) in cows fed the sainfoin diet. The reticular inflow of trans-9, trans-12-C18:2 and cis-12, trans-10 C18:2 was greater (P ≤ 0.024) in the sainfoin diet group. The cows fed sainfoin diet had a lower (P ≤ 0.038) apparent ruminal biohydrogenation of cis-9-C18:1 and C18:3n-3, compared to the cows fed the control diet. The sainfoin diet group had greater (P ≤ 0.018) C18:3n-3 and cis-9, cis-12-C18:2 proportions in the milk FA profile compared to the control diet group. Transfer efficiencies from feed to milk of C18:2, C18:3n-3 and unsaturated FA were greater (P ≤ 0.0179) for the sainfoin diet. Based on the results, it could be concluded that replacing grass silage by sainfoin silage in dairy cow rations reduces ruminal C18:3n-3 biohydrogenation and improves milk FA profile.     

Effect of several doses of zeolite A on feed intake,energy metabolism and on mineral metabolism in dairy cows around calving

The object of the present study was to determine the influence of different zeolite A doses on dry matter intake (DMI) and mineral metabolism, and to evaluate an optimum dosage for preventing hypocalcaemia. Eighty pregnant dry cows were assigned to four groups (I–IV). They were fed a total mixed ration (TMR) ad libitum. Groups II, III and IV received an average daily dose of 12, 23 and 43 g zeolite A/kg DM for the last 2 weeks prepartum. Individually DMI was recorded daily. Blood and urine samples were taken before, during and after zeolite A supplementation. Serum was analysed for Ca, Mg, P_i, K, non‐esterified fatty acids and β‐hydroxybutyrate (BHB). Urine was analysed for Ca, Mg, P_i, K and net acid‐base excretion (NABE). After calving, milk yield (fat corrected milk) and milk composition were determined. During zeolite A supplementation, mean DMI of Group IV (7.3 ± 1.3 kg/cow/day) was significantly lower compared to Groups I–III (10.1, 10.9, 9.5 kg/cow/day). The reduced feed intake of Group IV resulted in significantly increased BHB as well as decreased NABE after calving. Zeolite A supplementation in higher doses (III and IV) had a stabilizing effect on Ca metabolism around calving for older cows, whereas cows in Groups I and II showed a subclinical hypocalcaemia. The mean serum Mg concentration decreased significantly in older cows in Group IV at calving. The mean P_i concentration in cows of Group IV decreased into ranges of hypophosphataemia already 1 week after beginning of zeolite A feeding. The mean DMI postpartum as well as the milk yield was not affected by zeolite A supplementation. Feeding of 23 g zeolite A/kg DM TMR prepartum proved to be an adequate dosage for reducing subclinical hypocalcaemia frequency without significant effects on feed intake and P_i concentration in serum.     

Performance,body fat reserves and plasma metabolites in Brown Swiss dairy cows: Indoor feeding versus pasture‐based feeding

Feeding dairy cows indoors or on pasture affects not only labour, machinery and housing costs, but also animals’ performance and metabolism. This study investigates the effects of indoor feeding (IF) with a partial‐mixed ration (PMR) versus pasture‐based feeding (PF) on milk production, fertility, backfat thickness (BFT), body weight (BW) loss and energy metabolism of Brown Swiss (BS) dairy cows with similar genetic production potential. The IF herd consisted of 13 cows fed a PMR composed of maize and grass silage plus protein concentrate according to each cow's requirements. The PF herd consisted of 14 cows offered barn‐ventilated hay ad libitum after calving from January until March and grazed on semi‐continuous pastures during the vegetation period. The IF cows produced more energy‐corrected milk (ECM) per standard lactation (9,407 vs. 5,960 kg; p < .01), more milk fat (378 vs. 227 kg; p < .01) and milk protein (326 vs. 215 kg; p < .01). The calving interval (377 vs. 405 days; p < .01) and time empty (86 vs. 118 days; p < .01) were shorter in the PF compared to IF, possibly also due to different selection criteria for maintaining the respective seasonal calving rhythm. The empty body fat loss calculated according to BCS until its nadir was higher in IF cows (IF: 10.4 vs. PF: 4.8 MJ/day; p < .01), but no differences were noted in total body fat loss estimated via BFT (p = .24). However, PF had lower blood glucose concentration at all investigated time points, but no differences occurred in serum non‐esterified fatty acid and β‐hydroxybutyrate concentrations post‐partum. In conclusion, BS cows were equally well suited for the IF with PMR and the PF system investigated here without developing a prominent metabolic load despite differences in nutrient supply. As such, investigated BS dairy cows in our trial seem to have a high capacity for metabolic adaptation to different production systems.     

Influence of fibrolytic enzymes in total mixed ration containing urea-molasses-treated sugarcane bagasse on the performance of lactating Holstein–Friesian crossbred cows

The aim of this study was to determine the effect of different levels of fibrolytic enzyme on nutrient utilization and milk production in dairy cows. Four multiparous early-to-mid-lactation Holstein–Friesian crossbred cows were randomly allocated in a 4 × 4 Latin square design. Cows were fed a balanced total mixed ration (TMR) on a dry matter (DM) basis containing 0, 1.2, 2.4, and 3.6 g/kg DM of fibrolytic enzyme in TMR, where the TMR comprises 60% concentrate supplemented with a fibrolytic enzyme at 0, 2, 4, and 6 g/kg DM of concentrate, and 40% urea-molasses-treated sugarcane bagasse (UMSB) was used as a roughage source. Fibrolytic enzyme supplementation in TMR containing UMSB did not affect dry matter intake (DMI) of dairy cows (p > 0.05). There was a quadratic effect of fibrolytic enzyme levels on the digestibility of DM, organic matter (OM), neutral detergent fiber (NDF), and acid detergent fiber (ADF) (p < 0.05), and the maximal response was reached at 1.2–2.4 g/kg DM of fibrolytic enzyme added in the TMR. Furthermore, 3.5% fat-corrected milk, milk fat, total volatile fatty acids, and propionic acid were greater in a cow fed with 1.2–2.4 g/kg DM of fibrolytic enzyme, resulting in a lower ratio of acetic acid to propionic acid (p < 0.05). In conclusion, adding a fibrolytic enzyme in TMR containing UMSB improved nutrient utilization, rumen fermentation, and milk production of lactating dairy cows.     

Effects of Antidesma thwaitesianum Muell. Arg. pomace as a source of plant secondary compounds on digestibility,rumen environment,hematology, and milk production in dairy cows

Mao pomace meal (MPM) contains condensed tannins and saponins at 92 and 98 g/kg, respectively, and these substances can be used to manipulate ruminal fermentation in ruminant. Four multiparous lactating Holstein cows with 45 ± 5 days in milk were randomly assigned according to a 4 × 4 Latin square design to receive four different levels of MPM supplementation at 0, 100, 200, and 300 g/head/day, respectively. Cows were fed with concentrate diets at 1:1.5 of concentrate to milk yield ratio and urea‐treated (3%) rice straw was fed ad libitum. The results revealed that feed intake, nutrient digestibility, blood urea nitrogen, and hematological parameters were not affected by MPM supplementation (p > 0.05). However, ruminal pH and propionate were increased quadratically (p < 0.05) in cows receiving MPM whereas acetate, acetate to propionate ratio and estimate methane production were decreased (p < 0.05). Supplementation of MPM linearly decreased ruminal ammonia nitrogen and protozoal population at 4 hr postfeeding (p < 0.05). Milk production and milk composition were similar among treatments (p > 0.05). In conclusion, supplementation of MPM at 200 g/head/day could modify ruminal fermentation and reduce methane production without adverse effect on feed intake, digestibility, hematological parameters, and milk production in dairy cows.