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 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 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.     

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.     

Effects of red cabbage extract rich in anthocyanins on rumen fermentation,rumen bacterial community,nutrient digestion,and plasma indices in beef bulls

Dietary anthocyanins (ATH) have probiotic and antioxidant functions in humans. They may also have beneficial impacts on rumen microorganisms and subsequently nutrient digestion in cattle. The experiment aimed to study the effects of dietary red cabbage extract (RCE) rich in ATH on rumen fermentation, rumen bacterial community, and nutrient digestibility in beef bulls. Eight Simmental beef bulls and two RCE levels (0 and 120 g/d) were allocated in a replicated 2 × 2 crossover design. Each experimental period included 15 days for adaptation and subsequent 5 days for sampling. The results showed that dietary addition of RCE increased the ruminal concentration of total volatile fatty acids and the molar proportion of propionate, decreased the acetate to propionate ratio, and tended to decrease the molar proportion of acetate, but it did not affect the ruminal pH and the concentrations of ammonia N, microbial CP, monophenols, polyphenols, and total phenolics. ATH was undetectable in the ruminal fluid of beef bulls in both groups. RCE did not affect the alpha diversity of rumen bacterial community, and the relative abundances of major rumen bacteria at the phylum level, but it increased the relative abundances of Ruminobacter and Anaerovibrio and tended to increase the relative abundances of Oribacterium and Monoglobus at the genus level. RCE tended to increase the plasma concentrations of globulin and total protein, but it did not affect the plasma albumin, urea, triglyceride, glucose, and antioxidant activities. Dietary addition of RCE did not affect the apparent nutrient digestibility. In conclusion, the ATH in RCE was highly hydrolysable in rumen fluid. Dietary addition of RCE increased the ruminal concentration of total volatile fatty acids, decreased the acetate to propionate ratio, and slightly modified the rumen bacterial community, but it did not affect the nutrient digestibility and the plasma antioxidants in beef bulls.     

Ground,dry-rolled and steam-processed barley grain for midlactation Holstein cows

Fine grinding of barley grain has traditionally been considered to be a potential risk to rumen function, feed intake and milk yield. These concerns are thought to be reduced by steam-rolling or coarse dry rolling. We hypothesized that finely ground barley grain is as effective in stimulating feed intake and milk production as are dry- and steam-rolled barley grain, and so the objective was to determine effects of feeding either (1) finely ground, (2) steam-rolled, (3) finely dry-rolled, or (4) coarsely dry-rolled barley grain on rumen fermentation, digestibility and milk yield and composition. Eight multiparous midlactation Holstein cows were used in a replicated 4×4 Latin square design experiment with four periods of 21 d. Diets contained 256 g barley grain/kg on a dry matter (DM) basis. Processing method did not affect milk yield and composition, DM intake, rumen pH and volatile fatty acids, fecal and urine pH, and apparent total tract nutrient digestibility. Results suggest that finely ground barley grain is no different than dry-rolled and steam-rolled barley grains in stimulating feed intake and productivity of midlactation cows, when 256 g of dietary DM/kg is barley grain.     

Inclusion of cocoa by-product in the diet of dairy sheep: Effect on the fatty acid profile of ruminal content and on the composition of milk and cheese

In this study, we hypothesized that dietary cocoa bean shell (CBS) as a partial replacer of human edible cereal grains in the diet of lactating ewes may affect performance and milk and cheese composition. Twenty Comisana lactating ewes allotted into control (CTRL; n = 10) or cocoa (CBS; n = 10) group received alfalfa hay ad libitum and 800 g of conventional (CTRL) or experimental (CBS) concentrate containing 11.7% CBS to partially replace corn and barley of the CTRL concentrate. Milk yield and composition did not differ between groups, and only urea concentration was lower in CBS milk. Dietary CBS increased cheese fat and reduced protein percentage in CBS group. Fatty acid composition of rumen content partially reflected that of the ingested diet, with total saturated fatty acids (SFA), total monounsaturated fatty acids (MUFA), 16:0, 18:0 and 18:1c9 greater in the CBS group. Moreover, all the identified trans- and cis-18:1 isomers were greater in CBS rumen content. Milk and cheese showed a similar fatty acid composition. Total MUFAs were greater in milk and cheese of CBS, mainly due to the proportion of 18:1c9, and conversely, total polyunsaturated fatty acids (PUFA), PUFAn-6 and PUFAn-6-to-PUFAn-3 ratio was greater in CTRL group. Concluding, the inclusion of CBS in the diet of lactating ewes within the limit imposed by the current legislation did not cause detrimental effects on animal performance and milk composition. Interestingly, dietary CBS reduced milk urea concentration probably due to the phenols contained in CBS concentrate. However, our results support that biohydrogenation was weakly impaired by dietary CBS. Finally, CBS negatively affected cheese nutritional characteristics due to lower protein and greater fat content, but improved fat health indexes in milk and cheese.     

Garlic skin induces shifts in the rumen microbiome and metabolome of fattening lambs

Garlic (Allium sativum L.) and its constituents have been shown to modify rumen fermentation and improve growth performance. Garlic skin, a by-product of garlic processing, contains similar bioactive components as garlic bulb. This study aimed to investigate the effects of garlic skin supplementation on growth performance, ruminal microbes, and metabolites in ruminants. Twelve Hu lambs were randomly assigned to receive a basal diet (CON) or a basal diet supplemented with 80 g/kg DM of garlic skin (GAS). The experiment lasted for 10 weeks, with the first 2 weeks serving as the adaptation period. The results revealed that the average daily gain and volatile fatty acid concentration were higher (P < 0.05) in lambs fed GAS than those in the CON group. Garlic skin supplementation did not significantly (P > 0.10) affect the α-diversity indices, including the Chao1 index, the abundance-based coverage estimator value, and the Shannon and Simpson indices. At the genus level, garlic skin supplementation altered the ruminal bacterial composition by increasing (P < 0.05) the relative abundances of Prevotella, Bulleidia, Howardella, and Methanosphaera and decreasing (P < 0.05) the abundance of Fretibacterium. Concentrations of 139 metabolites significantly differed (P < 0.05) between the GAS and the CON groups. Among them, substrates for rumen microbial protein synthesis were enriched in the GAS group. The pathways of pyrimidine metabolism, purine metabolism, and vitamin B6 metabolism were influenced (P < 0.05) by garlic skin supplementation. Integrated correlation analysis also provided a link between the significantly altered rumen microbiota and metabolites. Thus, supplementation of garlic skin improved the growth performance of lambs by modifying rumen fermentation through shifts in the rumen microbiome and metabolome.     

Effects of dietary copper on growth performance, nutrient digestibility and fiber characteristics in cashmere goats during the cashmere slow-growing period

Thirty-six 2.5-year-old wether Inner Mongolian White Cashmere Goats (IMWG) (BW = 42.7 ± 3.44 kg) were used to determine the effects of dietary copper (Cu) concentration on growth performance, nutrient digestibility and fiber characteristics during the cashmere slow-growing period. Wethers were stratified by weight and randomly assigned to four dietary treatments, which included a control diet containing 5.60 mg Cu/kg DM, the control diet supplied, respectively, with 10, 20 and 30 mg Cu/kg DM (total dietary Cu level of 5.60, 15.6, 25.6 and 35.6 mg/kg DM). The experiment lasted 50 days including a 10-day preliminary trial and 10-day metabolism trial. Average daily feed intake (ADFI) did not differ among treatment groups (P > 0.05), except that the supplement providing 30 mg Cu/kg DM decreased average daily gain and gain efficiency (P < 0.05). Copper supplementation had no influence on digestibility of DM, CP and ADF (P > 0.05), however, NDF digestibility of the treatment group supplemented with 30 mg Cu/kg DM was lower compared with that of other groups (P < 0.05). Length and growth rate of cashmere fiber were higher in the treatment group supplemented with 20 mg Cu/kg DM compared with other groups (P < 0.05), but cashmere diameter was not affected by Cu supplementation (P > 0.05). In conclusion, supplementation of Cu at the levels of 10, 20 and 30 mg/kg DM to the basal diet containing 5.60 mg Cu/kg DM had no influence on ADFI or nutrient digestibility of DM, CP and ADF in cashmere goats, while 30 mg Cu/kg DM supplementation had a negative effect on growth performance and NDF digestibility. However, 20 mg Cu/kg DM supplementation of the basal diet enhanced cashmere growth. Hence, the appropriate supplemental level during the cashmere slow-growing period is deemed to be 20 mg Cu/kg DM (total dietary Cu level of 25.6 mg/kg DM).     

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.     

Effects of sodium selenite and coated sodium selenite on lactation performance,total tract nutrient digestion and rumen fermentation in Holstein dairy cows

Se can enhance lactation performance by improving nutrient utilization and antioxidant status. However, sodium selenite (SS) can be reduced to non-absorbable elemental Se in the rumen, thereby reducing the intestinal availability of Se. The study investigated the impacts of SS and coated SS (CSS) supplementation on lactation performance, nutrient digestibility, ruminal fermentation and microbiota in dairy cows. Sixty multiparous Holstein dairy cows were blocked by parity, daily milk yield and days in milk and randomly assigned to five treatments: control, SS addition (0.3 mg Se/kg DM as SS addition) or CSS addition (0.1, 0.2 and 0.3 mg Se/kg DM as CSS addition for low CSS (LCSS), medium CSS (MCSS) and high CSS (HCSS), respectively). Experiment period was 110 days with 20 days of adaptation and 90 days of sample collection. Dry matter intake was higher for MCSS and HCSS compared with control. Yields of milk, milk fat and milk protein and feed efficiency were higher for MCSS and HCSS than for control, SS and LCSS. Digestibility of DM and organic matter was highest for CSS addition, followed by SS addition and then control. Digestibility of CP was higher for MCSS and HCSS than for control, SS and LCSS. Higher digestibility of ether extract, NDF and ADF was observed for SS or CSS addition. Ruminal pH decreased with dietary Se addition. Acetate to propionate ratio and ammonia N were lower, and total volatile fatty acids (VFAs) concentration was greater for SS, MCSS and HCSS than control. Ruminal H ion concentration was highest for MCSS and HCSS and lowest for control. Activities of cellobiase, carboxymethyl-cellulase, xylanase and protease and copies of total bacteria, fungi, Ruminococcus flavefaciens, Fibrobacter succinogenes and Ruminococcus amylophilus increased with SS or CSS addition. Activity of α-amylase, copies of protozoa, Ruminococcus albus and Butyrivibrio fibrisolvens and serum glucose, total protein, albumin and glutathione peroxidase were higher for SS, MCSS and HCSS than for control and LCSS. Dietary SS or CSS supplementation elevated blood Se concentration and total antioxidant capacity activity. The data implied that milk yield was elevated due to the increase in total tract nutrient digestibility, total VFA concentration and microorganism population with 0.2 or 0.3 mg Se/kg DM from CSS supplementation in dairy cows. Compared with SS, HCSS addition was more efficient in promoting lactation performance of dairy cows.     

Effects of isobutyrate on rumen fermentation, lactation performance and plasma characteristics in dairy cows

The objective of this study was to evaluate effects of isobutyrate supplementation on rumen fermentation, lactation performance and plasma characteristics of dairy cows. Twenty multiparous second filial generation (F2) cows of a cross between Chinese Jinnan Yellow and Holstein cows at 148 ± 4.5 days in milk and 22.3 ± 0.81 kg milk production were used in a replicated 4 × 4 Latin square experiment. The treatments were: control (without isobutyrate), low (LIB), medium (MIB) and high (HIB) isobutyrate supplementation of 20, 40 and 60 g per cow per day, respectively. Experimental periods were 30 days with 15 d of adaptation and 15 d of data collection. Dry matter (DM) intake was not affected by increasing isobutyrate supplementation, but milk yields were highest for the 40 g/d isobutyrate supplementation level, where proportion of milk fat, true protein and lactose were minimized. Ruminal pH (6.38–6.24) and ammonia N (13.8–11.1 mg/100 ml) were linearly (P<0.01) decreased, whereas total VFA concentration (124–131 mM) increased at a decreasing rate with increasing isobutyrate supplementation. The ratio of acetate to propionate increased linearly (P<0.01) from 2.77 to 4.43 as isobutyrate supplementation increased due to the increase in acetate production and decrease in propionate production. Digestibilities of OM in the total tract increased linearly (P<0.01) as isobutyrate supplementation increased, digestibilities of DM and EE were highest for the 40 g/d isobutyrate supplementation level, digestibilities of CP, aNDF and ADF increased at a decreasing rate with increasing isobutyrate supplementation. Plasma concentrations of glucose and growth hormone linearly (P<0.03) increased, whereas concentrations of non-esterified fatty acids linearly (P<0.01) decreased. Results indicate that supplementation of this diet with isobutyrate changed the rumen fermentation pattern towards acetate production, improved digestion and modified plasma concentrations of glucose and growth hormone. This suggests that isobutyrate stimulated digestive microorganisms or enzymes in a dose-dependent manner with the optimum isobutyrate dose at about 40 g per cow per day in terms of improved digestion.     

Effects of canola oil and antioxidants on performance,serum parameters,carcass traits,and rumen fermentation patterns of Nellore cattle

Several nutritional strategies have been used in beef cattle production in order to increase animal performance and profitability. However, in the past two decades, the increase of consumer preference for functional foods has driven the investigation for improving food via adding functional substances to animal diets. We evaluated the effect of canola oil supplementation associated with vitamin E and selenium on performance, rumen metabolism, carcass traits, meat tenderness, and serum, liver, and meat status of antioxidants in finishing Nellore males. Animals were fed for 106 days in a feedlot and were randomly distributed in a 2 × 2 factorial arrangement: two levels of oil in the diet (no inclusion and 3% canola oil, defined as diet without oil inclusion (NO) and effect of oil (OIL), respectively) and two levels of antioxidants in the diet (no inclusion and 2.5 mg of Se/kg of DM + 500 UI of vitamin E/kg of DM, defined as diet without antioxidant inclusion (NA) and effect of the antioxidants (ANT), respectively). DM intake (kg/day) was evaluated daily; performance and serum were analysed at the beginning of the feedlot and every 28 days. Animals were slaughtered and hot carcass weight (kg) was recorded; ruminal fluid and liver samples were collected. At 24 h postmortem, carcass pH was recorded and the Longissimus thoracis was sampled. There was no significant effect of the OIL*ANT interaction (P > 0.05) for any trait evaluated. Bulls fed OIL presented greater final BW (P < 0.01), average daily gain (kg/day; P < 0.01), feed efficiency (P < 0.01), rump fat thickness (P8RF; P < 0.05), and greater tenderness; the ANT diet increased P8RF (P < 0.05). The levels of selenium and vitamin E in serum, liver, and meat were increased (P < 0.01) with the inclusion of ANT. ANT did not change triiodothyronine (T3, ng/mL) and thyroxine (T4, µg/gL) serum concentrations but decreased serum glucose levels. The treatments did not affect (P > 0.05) ruminal parameters or the protozoa population. Our results showed that the inclusion of 3% canola oil in the diet DM increased performance, feed efficiency, carcass fat deposition, and tenderness, with no effect on rumen fermentation and protozoa population of Nellore cattle in a feedlot system. The inclusion of ANT in the cattle diet did not affect performance or rumen parameters. However, the levels of ANT were increased in the serum, liver, and meat, enriching the final product with these compounds.     

Effect of increasing doses of a microencapsulated blend of essential oils on performance of lactating primiparous dairy cows

This study determined impacts of a commercial blend of microencapsulated essential oils (EO), fed at increasing dose levels to high yielding primiparous dairy cows, on milk yield and composition. Eight pregnant Holstein heifers, selected to have their parturition within a period of 30 d, were kept in tie stalls equipped for individual feeding, and with free access to water, from the 7th month of gestation. At an average of 40 d postpartum, cows were assigned to one of four dietary EO levels in a replicated 4 × 4 Latin square design. The experimental diets (i.e., corn silage, fescue hay and a compound feed, 6.5, 4.4 and 8.7 kg DM/d respectively) differed only in the addition level of a microencapsulated EO supplement (RumaXol Feed) mixed at different levels into the compound feed (fed at 1 kg/cow day) in order to provide 0, 0.32, 0.64 and 0.96 g/d of the EO mixture. The experiment had four experimental periods of 21 d, with the last 5 d used for collection of faeces and urine, for milk yield and composition recording and measurement of cow biometric data. The dietary EO supplementation had no effect on dry matter (DM) intake, water consumptions or faecal DM, while urine density was (P=0.01) lower at the intermediate EO dosages. Digestibility and biometric measures of cows were not modified by EO feeding. The protein content of milk tended (P=0.06) to be higher at the intermediate EO dosages, as did (P=0.05) the milk energy concentration. However milk and milk component yields were not affected by EO feeding level.     

Effects of replacing soybean meal with pumpkin seed cake and dried distillers grains with solubles on milk performance and antioxidant functions in dairy cows

Pumpkin seed cake (PSC), a byproduct of pumpkin seed oil processing, is used in ruminant feed as a beneficial protein source. Experiments were conducted to evaluate PSC as a substitute for soybean meal in the diets of lactating cows based on performance, rumen fermentation, antioxidant function and nitrogen partitioning. Six multiparous lactating cows were used in a replicated 3 × 3 Latin square experiment with 27-day periods. The cows were randomly divided into three treatment groups: group (1) was fed a diet containing no PSC (0PSC), and groups (2) and (3) were fed diets in which soybean meal was replaced with PSC and dried distillers grains with solubles (DDGS) at levels of 50% (50PSC) and 100% (100PSC), respectively. The diets were isonitrogenous and contained identical roughage but different proportions of PSC and DDGS. Replacement of soybean meal with PSC and DDGS did not influence rumen degradation, milk performance, rumen fermentation, DM intake or apparent total tract digestibility, and nitrogen partitioning between milk, feces and urine did not differ in the animals fed the three diets. However, compared with a diet containing no PSC, the total antioxidant capacity (P < 0.05) and antioxidant enzymes (total superoxide dismutase, glutathione peroxidase and catalase) activities (P < 0.05) were increased in the animals that received the 50PSC and 100PSC diets. In contrast, addition of PSC significantly reduced concentrations of aspartate transaminase (P < 0.05), alkaline phosphatase (P < 0.05) and malondialdehyde (P < 0.05) in the plasma. These results demonstrate that PSC can be completely substituted for soybean meal in the diet of dairy cows without any negative impact on milk performance, rumen fermentation or apparent digestibility and that this dietary change improves antioxidant functions and blood parameters in dairy cows, indicating that PSC has the potential for use as a feed source for dairy cows.     

Effects of dietary crude protein and tannic acid on rumen fermentation,rumen microbiota and nutrient digestion in beef cattle

The objectives of the trial were to study the effects of dietary crude protein (CP) and tannic acid (TA) on rumen fermentation, microbiota and nutrient digestion in beef cattle. Eight growing beef cattle (live weight 350 ± 25 kg) were allocated in a 2 × 2 crossover design using two levels of dietary CP [111 g/kg dry matter (DM) and 136 g/kg DM] and two levels of TA (0 and 16.9 g/kg DM) as experimental treatments. Each experimental period lasted 19 d, consisting of 14-d adaptation and 5-d sampling. The impacts of dietary CP and TA on ruminal microbiota were analysed using high-throughput sequencing of 16S rRNA gene. Results indicated that no interactions between dietary CP and TA were found on rumen fermentation and nutrient digestibility. Increasing dietary CP level from 111 to 136 g/kg DM increased the ruminal concentrations of ammonia nitrogen (NH₃-N) (p < 0.01) and improved the CP digestibility (p < 0.001). Adding TA at 16.9 g/kg DM inhibited rumen fermentation and decreased the digestibility of dietary CP (p < 0.001), DM (p < 0.05) and organic matter (p < 0.01). Increasing the dietary CP level or adding TA did not affect the relative abundances of the major bacteria Firmicutes and Proteobacteria at the phylum level and Prevotella_1 and Christensenellaceae_R-7_group at the genus level, even though adding TA increased the Shannon index of the ruminal bacterial community. TA was partly hydrolysed to pyrogallol, gallic acid and resorcinol in rumen fluid and the inhibitory effects of TA on rumen fermentation and nutrient digestibility could have been resulted from the TA metabolites including pyrogallol, gallic acid and resorcinol as well as the protein-binding effect.     

Influence of exogenous enzymes on nutrient digestibility, extent of ruminal fermentation as well as milk production and composition in dairy cows

This experiment studied effects of a mixture of exogenous enzymes (ZADO^®) from anaerobic bacteria on ruminal fermentation, feed intake, digestibility, as well as milk production and composition in cows fed total mixed rations (TMRs; 0.7 corn silage and 0.3 of a concentrate mixture). Twenty lactating multiparous Brown Swiss cows (500 ± 12.4 kg live weight) were randomly assigned into two experimental groups of 10 immediately after calving and fed a TMR with or without (CTRL) addition of 40 g/cow/d of enzymes for 12 weeks. Addition of enzymes increased (P<0.05) rumen microbial N synthesis. Intake of dry matter (DM) and organic matter (OM) was positively influenced (P<0.05) by supplementation, and digestibility of all nutrients was higher (P<0.05) in the total tract of supplemented cows, although the magnitude of the improvement varied among nutrients, with the highest improvement in aNDFom and ADFom (418–584 and 401–532 g/kg respectively; P<0.05) than the other nutrients. Supplementation of enzymes also increased (P<0.05) rumen ammonia N and total short chain fatty acid (SCFA) concentrations, and individual SCFA proportions were also altered with an increase in acetate (61.0–64.8 mol/100 mol; P=0.05) before feeding, and acetate and propionate increased 3 h post-feeding (60.0–64.0 and 18.3–20.8 mol/100 mol respectively; P<0.05). Milk and milk protein production was higher (12.8–15.7 and 0.45–0.57 kg/d respectively; P<0.05) for cows fed the ZADO^® supplemented diet. This exogenous enzyme product, supplemented daily to the TMR of cows in early lactation, increased milk production due to positive effects on nutrient intake and digestibility, extent of ruminal fermentation and microbial protein synthesis.     

Effect of dietary cobalt supplementation on plasma and rumen metabolites in Mehraban lambs

Two experiments were conducted to study the effects of different levels of dietary cobalt on performance, plasma and rumen metabolites and nutrient digestibility in Mehraban male lambs. Experiment 1: 28, 8–9-month-old lambs were randomly divided into four groups. Animals were fed a basal diet containing 0.088 mg Co/kg DM and were supplied with 0 (control), 0.25, 0.50, or 1.00 mg Co/kg DM as reagent grade CoSO₄·7H₂O. The experiment lasted for 70 days. Experiment 2: four lambs from each group in Experiment 1 were randomly allocated to the individual metabolic crates to measure the effects of dietary Co on nutrient digestibility. Final body weight, average daily gain and gain efficiency were higher (p < 0.05) in the group supplemented with 0.50 mg Co/kg DM compared to other groups. Plasma glucose and vitamin B₁₂ concentrations increased (p < 0.05) at all levels of Co supplementation on day 68 of the experiment and for vitamin B₁₂ were higher (p < 0.05) at 0.50 and 1.00 mg Co/kg DM compared to 0.25 mg Co/kg DM. There was no significant difference among treatments for TVFA and ruminal fluid pH. Digestibility of dry matter, organic matter, crude protein and neutral detergent fiber increased (p < 0.05) by Co supplementation, but did not differ among Co supplied treatments. The obtained results showed that lambs fed the control diet containing 0.088 mg Co/kg DM had a reduced appetite and gained less than the supplemented animals, suggesting that the level of 0.088 mg Co/kg DM was inadequate for normal growth of Mehraban male lambs, and a total level of 0.58 mg Co/kg DM might be optimum level for enhancing performance.     

Assessment of a brown midrib (BMR) mutant gene on the nutritive value of sudangrass using in vitro and in vivo techniques

The brown midrib (BMR) gene has been reported to reduce the lignin concentration in plants, which contributed to increased fiber digestion in ruminants. Three studies were completed to compare the digestibility of a BMR mutant of sudangrass (sorghum bicolor subsp. Drummondii) versus a non-BMR (‘Piper’) variety when included in diets fed to sheep (Study 1), to complete a rumen in vitro assessment of sheep and lactating cow diets (Study 2), and to compare digestibility when included in the diet fed to lactating dairy cows (Study 3). Four wether sheep were used in a 2 × 2 Latin square experiment (Study 1) with total fecal collection to determine total tract apparent digestibility of pelleted Piper (P) and BMR (P-BMR) sudangrass hays. Forage pellets consisted of either P-BMR or P hay with added urea to meet the maintenance crude protein (CP) requirement of the sheep. Digestibility of organic matter (OM; P<0.01), dry matter (DM; P<0.01), acid detergent fiber (ADF; P<0.05), and neutral detergent fiber (aNDFom; P<0.07) was higher for P-BMR than P sudangrass. In vitro rumen digestibility of aNDFom using cattle rumen fluid was higher at 24 (P<0.01), 48 (P<0.01) and 72 h (P<0.01) of fermentation for P-BMR versus P (Study 2). Four lactating Holstein dairy cows (251 ± 30 days in milk) and fitted with ruminal and duodenal cannulae were used in a 4 × 4 Latin square experiment. Total mixed rations (TMR) contained 180 g/kg DM shredded sudangrass hay and 180 g/kg sliced alfalfa hay, but the proportion of P to P-BMR sudangrass varied as 100:0, 66:34, 34:66, or 0:100. Yields of milk and milk protein were highest at the 66:34 level (Quadratic: P=0.06 and 0.07, respectively), but composition of milk fat, protein and lactose, as well as DM intake, did not differ (Study 3), probably because forestomach and total tract apparent digestion of aNDFom and OM did not differ due to sudangrass source.     

Replacing soybean meal with flax seed meal: effects on nutrient digestibility,rumen microbial protein synthesis and growth performance in sheep

Flax seed meal (FSM) is rich in various nutrients, especially CP and energy, and can be used as animal protein feed. In animal husbandry production, it is a long-term goal to replace soybean meal (SBM) in animal feed with other plant protein feed. However, studies on the effects of replacing SBM with FSM in fattening sheep are limited. The aim of this experiment was to study the effects of replacing a portion of SBM with FSM on nutrient digestibility, rumen microbial protein synthesis and growth performance in sheep. Thirty-six Dorper × Small Thin-Tailed crossbred rams (BW = 40.4 ± 1.73 kg, mean ± SD) were randomly assigned into four groups. The dietary treatments (forage/concentrate, 45 : 55) were isocaloric according to the nutrient requirements of rams. Soybean meal was replaced with FSM at different levels (DM basis): (1) 18% SBM (18SBM), (2) 12% SBM and 6% FSM (6FSM), (3) 6% SBM and 12% FSM (12FSM) and (4) 18% FSM (18FSM). The rams were fed in individual pens for 60 days, with the first 10 days for adaptation to diets, and then the digestibility of nutrients was determined. There was no significant difference in DM intake, but quadratic (P < 0.001) effects on the average daily gain and feed efficiency were detected, with the highest values in the 6FSM and 12FSM groups. For DM and NDF digestibility, quadratic effects were observed with the higher values in the 6FSM and 12FSM groups, but the digestibility of CP linearly decreased with the increase in FSM in the diet (P = 0.043). There was a quadratic (P < 0.001) effect of FSM inclusion rate on the estimated microbial CP yield. However, the values of intestinally absorbable dietary protein decreased linearly (P < 0.001). For the supply of metabolisable protein, both the linear (P = 0.001) and quadratic (P = 0.044) effects were observed with the lowest value in the 18FSM group. Overall, the results indicated that SBM can be effectively replaced by FSM in the diets of fattening sheep and the optimal proportion was 12.0% under the conditions of this experiment.