Feeding Flaxseed and Lupins during the Transition Period in Dairy Cows: Effects on Production Performance, Fertility and Biochemical Blood Indices

Flaxseed and lupin seed were offered as an alternative dietary approach in dairy cows, through the partial substitution of soybean meal. Milk production and fertility traits were investigated. A total of 330 animals were allocated into two groups, treated (n = 176) and control (n = 154). From each group, 30 animals were selected for hematological and cytological studies. The experimental feeding period lasted for 81 days (25 days prepartum and 56 days postpartum). The control ration (group C) contained corn, barley, soybean meal, rapeseed cake, corn silage and lucerne hay; whereas, in the treatment group (group T), 50% of the soybean meal was replaced by an equal mixture of flaxseed and lupins. The two rations were formulated to be isonitrogenous and isoenergetic. Milk samples were analyzed for chemical composition, somatic cell count (SCC) content and total colony forming units (CFU). Blood samples were collected, and serum was analyzed for non-esterified fatty acids (NEFA), acute phase proteins (haptoglobin and serum amyloid) and lipid oxidation indices, namely thiobarbituric-acid-reactive substances (TBARS) and catalase activity. To assess polymorphonuclear neutrophils (PMN) numbers, endometrial samples from each cow were collected on days 21 and 42. No difference was recorded between groups in milk yield (p > 0.05). In multiparous cows, NEFA (mMol/L) concentrations were significantly lower in group T than in group C on day 14 (p > 0.009) and on day 42 (p = 0.05), while no difference was detected in the group of primiparous cows. At all time points, serum TBARS and catalase values were similar in both groups (p > 0.05). Multiparous cows in group T expressed the first postpartum estrus and conceived earlier than cows in group C (p ≤ 0.05). Between days 21 to 42 postpartum, the PMN reduction rate was higher in group T animals (p ≤ 0.05). Acute phase protein levels were in general lower in group T animals, and at specific time points differed significantly from group C (p ≤ 0.05). It was concluded that the partial replacement of soybean meal by flaxseed and lupins had no negative effect on milk yield or milk composition, and improved cow fertility; which, along with the lower cost of flaxseed and lupins mixture, may increase milk production profitability.

The Effects of Feeding Milled Rapeseed Seeds with Different Forage:Concentrate Ratios in Jersey Dairy Cows on Milk Production, Milk Fatty Acid Composition, and Milk Antioxidant Capacity

We aimed to evaluate the effects of milled rapeseed (MR) supplementation of low- or high-concentrate diets on milk production and composition, fatty acids (FAs) profile, and antioxidant capacity. Sixteen Jersey dairy cows were used in a 4 × 4 Latin square design, for four periods of 4 weeks, and assigned to four treatments as a 2 × 2 factorial design. Dietary treatments consisted of iso-nitrogenated total mixed rations with high (65:35; LC-low concentrate) or low (50:50; HC-high concentrate) forage:concentrate (FC) ratios, supplemented with MR to provide 30 g oil/kg dry matter (DM) (LR and HR), or without MR supplement (L and H). Increasing the proportion of concentrates led to an increase in DM intake (DMI), net energy (NE_L) intake, and milk production, but milk fat and protein content decreased. Supplementing diets with MR led to an increase in NE_L intake and milk production, but did not affect DMI and milk composition. Diets supplemented with MR caused a decrease in the concentration of FAs with atherogenic effect and the increase in the level of FAs beneficial for human health (C18:1 cis-9, C18:1 trans-11, and C18:3 n-3), while the decrease in the FC ratio had a negative effect on omega-3 FAs. An improvement in the antioxidant capacity of milk was observed with diets with the high FC ratio but also by supplementing the feed with MR. These results could contribute to the development of effective strategies to improve the nutritional quality of milk without affecting the productive performance of cows.

Oilseed Supplementation Improves Milk Composition and Fatty Acid Profile of Cow Milk: A Meta-Analysis and Meta-Regression

Oilseed supplementation is a strategy to improve milk production and milk composition in dairy cows; however, the response to this approach is inconsistent. Thus, the aim of this study was to evaluate the effect of oilseed supplementation on milk production and milk composition in dairy cows via a meta-analysis and meta-regression. A comprehensive and structured search was performed using the following electronic databases: Google Scholar, Primo-UAEH and PubMed. The response variables were: milk yield (MY), atherogenic index (AI), Σ omega-3 PUFA, Σ omega-6 PUFA, fat, protein, lactose, linoleic acid (LA), linolenic acid (LNA), oleic acid (OA), vaccenic acid (VA), conjugated linoleic acid (CLA), unsaturated fatty acid (UFA) and saturated fatty acid (SFA) contents. The explanatory variables were breed, lactation stage (first, second, and third), oilseed type (linseed, soybean, rapeseed, cottonseed, and sunflower), way (whole, extruded, ground, and roasted), dietary inclusion level, difference of the LA, LNA, OA, forage and NDF of supplemented and control rations, washout period and experimental design. A meta-analysis was performed with the “meta” package of the statistical program R. A meta-regression analysis was applied to explore the sources of heretogeneity. The inclusion of oilseeds in dairy cow rations had a positive effect on CLA (+0.27 g 100 g−1 fatty acids (FA); p < 0.0001), VA (+1.03 g 100 g−1 FA; p < 0.0001), OA (+3.44 g 100 g−1 FA; p < 0.0001), LNA (+0.28 g 100 g−1 FA; p < 0.0001) and UFA (+8.32 g 100 g−1 FA; p < 0.0001), and negative effects on AI (−1.01; p < 0.0001), SFA (−6.51; p < 0.0001), fat milk (−0.11%; p < 0.001) and protein milk (−0.04%; p < 0.007). Fat content was affected by animal breed, lactation stage, type and processing of oilseed and dietary NDF and LA contents. CLA, LA, OA and UFA, desirable FA milk components, were affected by type, processing, and the intake of oilseed; additionally, the concentrations of CLA and VA are affected by washout and design. Oilseed supplementation in dairy cow rations has a positive effect on desirable milk components for human consumption. However, animal response to oilseed supplementation depends on explanatory variables related to experimental design, animal characteristics and the type of oilseed.

Effects of feeding rumen-protected linseed fat to postpartum dairy cows on plasma n-3 polyunsaturated fatty acid concentrations and metabolic and reproductive parameters

High-yielding dairy cows experience a negative energy balance and inflammatory status during the transition period. Fat supplementation increases diet energy density, and plasma n-3 polyunsaturated fatty acids (PUFA) have been proposed to improve immune function. This study tested the hypothesis that dietary supplementation with a rumen-protected and n-3 PUFA-enriched fat could ameliorate both the energetic deficit and immune status of postpartum high-yielding dairy cows, improving overall health and reproductive efficiency. At 11 d in milk (DIM), cows were randomly allocated to groups (1) n-3 PUFA (n = 29), supplemented with encapsulated linseed oil supplying additional up to 64 g/d (mean 25 ± 4 g/d) of α-linolenic acid (ALA), or (2) control (n = 31), supplemented with hydrogenated palm oil without ALA content. Fat supplements of the n-3 PUFA and control groups were available through an automated, off-parlor feeding system, and intake depended on the cow's feeding behavior. Plasma ALA concentrations were higher in n-3 PUFA than control cows, following a linear relation with supplement ingestion, resulting in a lower n-6/n-3 ratio in plasma. Metabolic parameters (body condition score and glucose and β-hydroxybutyric acid blood concentrations) were unaffected, but milk yield improved with increased intake of fat supplements. Plasma total adiponectin concentrations were negatively correlated with ingestion of n-3 PUFA-enriched fat supplement, following a linear relation with intake. Conception rate to first AI increased with higher intake of both fats, but a decrease of calving-to-conception interval occurred only in n-3 PUFA cows. Postpartum ovarian activity and endometrial inflammatory status at 45 DIM were unaffected. In conclusion, this study evinced a positive linear relation between rumen-protected linseed fat intake and plasma n-3 PUFA concentrations, which modulated adiponectin expression and improved reproductive parameters.

Innovative high digestibility protein feed materials reducing environmental impact through improved nitrogen-use efficiency in sustainable agriculture

Sustainable development in agriculture brings both environmental and economic benefits. Contemporary agriculture is also about increasing nutrient use efficiency, especially nitrogen, as the critical nutrient causing the most significant environmental pressure. This creates the need to produce highly digestible protein feed with high bioavailability, reducing losses of biogenic elements to feces. In this review, the latest trends and the potential for their implementation in sustainable agriculture have been compared, as well as the need to reduce the negative environmental impact of agriculture has been demonstrated. Applying local protein sources to feed animals reduces greenhouse gas emissions associated with transportation. The production of highly digestible fodder leads to a reduction in environmental pollution caused by excessive nitrogen outflows. Another approach indecreasing ammonia emissions from livestock farming is feed protein reduction and amino acid supplementation. All of the aforementioned approaches may result in beneficial long-term changes, contributing to environmental safety, animal welfare and human health.

Role of nutraceuticals during the transition period of dairy cows: a review

The transition period of dairy cattle is characterized by a number of metabolic, endocrine, physiologic, and immune adaptations, including the occurrence of negative energy balance, hypocalcemia, liver dysfunction, overt systemic inflammatory response, and oxidative stress status. The degree and length of time during which these systems remain out of balance could render cows more susceptible to disease, poor reproductive outcomes, and less efficient for milk production and quality. Studies on both monogastrics and ruminants have reported the health benefits of nutraceuticals (e.g. probiotics, prebiotics, dietary lipids, functional peptides, phytoextracts) beyond nutritional value, interacting at different levels of the animal’s physiology. From a physiological standpoint, it seems unrealistic to disregard any systemic inflammatory processes. However, an alternate approach is to modulate the inflammatory process per se and to resolve the systemic response as quickly as possible.

To this aim, a growing body of literature underscores the efficacy of nutraceuticals (active compounds) during the critical phase of the transition period. Supplementation of essential fatty acids throughout a 2-month period (i.e. a month before and a month after calving) successfully attenuates the inflammatory status with a quicker resolution of phenomenon. In this context, the inflammatory and immune response scenario has been recognized to be targeted by the beneficial effect of methyl donors, such as methionine and choline, directly and indirectly modulating such response with the increase of antioxidants GSH and taurine. Indirectly by the establishment of a healthy gastrointestinal tract, yeast and yeast-based products showed to modulate the immune response, mitigating negative effects associated with parturition stress and consequent disorders.

The use of phytoproducts has garnered high interest because of their wide range of actions on multiple tissue targets encompassing a series of antimicrobial, antiviral, antioxidant, immune-stimulating, rumen fermentation, and microbial modulation effects. In this review, we provide perspectives on investigations of regulating the immune responses and metabolism using several nutraceuticals in the periparturient cow.

Whole-lactation feed intake, milk yield, and energy balance of Holstein and Swedish Red dairy cows fed grass-clover silage and 2 levels of byproduct-based concentrate

Ruminants can produce meat and milk from fibrous feed and byproducts not suitable for human consumption. However, high-yielding dairy cows are generally fed a high proportion of cereal grain and pulses, which could be consumed directly by humans. If high production of dairy cows could be maintained with ingredients of low human interest, the sustainability of dairy production would improve. In the present study, 37 multiparous [Holstein (n = 13) and Swedish Red (n = 24)] dairy cows were followed over a whole lactation. A low-concentrate diet of up to 6 kg concentrate per day (6kgConc) was fed to 27 cows, whereas 10 cows were fed a high-concentrate diet of up to 12 kg concentrate per day (12kgConc). The concentrate was mainly based on byproducts (sugar beet pulp, wheat bran, rapeseed meal, distiller's grain). Grass-clover silage of high digestibility was offered ad libitum. Over the whole lactation, cows on the 6kgConc diet had lower dry matter intake and higher forage intake than cows on the 12kgConc diet. Milk yield and energy balance were not influenced by dietary treatment. However, the cows on the 6kgConc diet numerically produced 2.4 kg less energy-corrected milk than cows on 12kgConc diet. The study lacked the statistical power to identify treatment effects on daily yield below 2.8 kg of milk due to low number of animals per treatment. Feed efficiency (as energy-corrected milk yield/dry matter intake or residual feed intake), body weight change, body condition change, milk fatty acid concentration in total milk fatty acids, plasma nonesterified fatty acids, glucose, β-hydroxybutyrate, and fertility measurements were not affected by diet, supporting the energy balance results. However, higher plasma concentrations of insulin-like growth factor-1 and insulin were observed in cows fed the 12kgConc diet. These findings show that cows can adapt to a high-forage diet virtually without human-grade ingredients, without compromising feed efficiency or energy balance, thereby contributing to sustainable food production.

Effects of Extruded Linseed and Soybean Dietary Supplementation on Lactation Performance, First-Service Conception Rate, and Mastitis Incidence in Holstein Dairy Cows

This study quantifies the effects of extruded linseed and soybean (ELS) dietary supplementation on milk yield, composition, and fatty acid profiles, as well as first-service conception rate in Holstein dairy cows. Seventy-eight open Holstein dairy cows were divided into two groups: (1) a control, which received a basal diet; and (2) a test group, which received a basal diet supplemented with the ELS (650 g/kg of extruded linseed and 150 g/kg of extruded soybean) at a rate of 100 g/kg. In the ELS group, milk yield per day and solid not fat (SNF) yield increased by 3.26% and 0.88%, respectively, in relation to the control. Percentage milk fat decreased significantly by 1.4% in the ELS group when compared with the control. The ELS supplement resulted in a decrease in saturated fatty acids (SFAs) and an increase in monounsaturated (MUFAs) and polyunsaturated fatty acids (PUFAs) in milk. In conclusion, the supplementation of dairy cow feed with 100 g/kg of ELS increases milk yield and milk unsaturated fatty acids (especially MUFAs and PUFAs). ELS supplementation also causes a decrease in percentage fat and SFA levels but does not affect the first-service conception rate or the incidence rate of mastitis.

Ruminal fermentation, kinetics, and total-tract digestibility of lactating dairy cows fed distillers dried grains with solubles in low- and high-forage diets

The objective of this study was to investigate the effects of concentrations of forages and corn distillers dried grains with solubles (DDGS) on ruminal fermentation, ruminal kinetics, and total-tract digestibility of nutrients in lactating dairy cows. Four lactating Holstein cows with ruminal cannulas were assigned to a 4 × 4 Latin square in a 2 × 2 factorial arrangement of treatments. Diets were formulated to contain low forage [LF; 17% forage neutral detergent fiber (NDF)] or high forage (HF; 24.5% forage NDF) and DDGS at 0 or 18% (0DG or 18DG) of diet dry matter (DM). Intake of DM was not affected by the diets. Daily mean ruminal pH was affected by forage NDF × DDGS interactions, as the lowest ruminal pH was observed among cows fed LF18DG (6.02). Apparent total-tract digestibility for DM, organic matter, crude protein, NDF, acid detergent fiber, and starch was not affected by diets. Cows fed LF diets had a greater total volatile fatty acid concentration compared with cows fed HF (122 vs. 116 mM). Molar proportions of acetate were greater for HF compared with that of LF diets (62.6 vs. 57.5 mmol/100 mmol) and greater for 0DG diet compared with that of 18DG diets (61.3 vs. 58.7 mmol/100 mmol) diets. The molar proportion of propionate was affected by forage × DDGS interaction as the greatest propionate molar proportion was observed with cows fed LF18DG diet (27.7 mmol/100 mmol). Also, molar proportion of butyrate was affected by forage × DDGS interaction, as the greatest butyrate molar proportion was observed in cows fed HF18DG diet (13.5 mmol/100 mmol). Average fractional dilution rate for all diets was 11.9%/h and was not affected by diets. Fractional passage rate of the solid phase was greater for HF than for LF (4.40 vs. 3.76%/h). The ruminal retention time of solid phase was greater for LF compared with HF diets (27.3 vs. 23.3 h). Fractional passage rate of DDGS was affected by forage × DG interaction, as the highest fractional passage rate of DDGS was observed with cows fed HF18DG diet (7.72%/h). Our results demonstrated that concentrations of forage, DDGS, and their interaction influence ruminal degradation and kinetics of diets fed. Diets formulated at 17% forage NDF at 17% (DM basis) can decrease milk fat concentration compared with diets formulated at 25% forage NDF. Additionally, feeding DDGS at 18% DM basis to lactating dairy cows did not affect milk fat concentration or yield.

Production of dairy cows fed distillers dried grains with solubles in low- and high-forage diets

The objective of the study was to investigate the effects of dietary forage and distillers dried grains with solubles (DDGS) concentration on the performance of lactating dairy cows. Twelve Holstein cows were blocked by parity and milk production and assigned to replicated 4 × 4 Latin squares with a 2 × 2 factorial arrangement of treatments. Diets were formulated to contain low forage [LF; 17% forage neutral detergent fiber (NDF)] or high forage (HF; 24.5% forage NDF) and DDGS at 0 or 18% of diet dry matter. The forage portion of the diet consisted of 80% corn silage and 20% alfalfa hay (dry matter basis). A portion of the ground corn and all of the expeller soybean meal and extruded soybeans from 0% DDGS diets were replaced with DDGS to formulate 18% DDGS diets. Overall, we found no interactions of forage × DDGS concentrations for any of the production measures. We observed no effect of diet on dry matter intake. Milk yield was greater when cows were fed LF diets compared with HF diets (43.3 vs. 41.5 kg/d). Milk fat concentration (3.03 vs. 3.38%) was lower for cows fed LF diets compared with HF diets, whereas protein concentration (3.11 vs. 2.98%) and yield (1.34 vs. 1.24 kg/d) were greater for cows fed LF diets compared with HF diets. Yields of fat, total solids, energy-corrected milk, and feed efficiency were not affected by diets. Cows partitioned equally for milk, maintenance, and body reserves. Replacing starch from ground corn and protein from soybean feeds with DDGS at either 17 or 24.5% of forage NDF concentration in the diet was cost-effective and did not affect the production performance of lactating dairy cows.

Effects of feeding extruded linseed on production performance and milk fatty acid profile in dairy cows: A meta-analysis

The objectives of this study were to quantify the effects on production performance and milk fatty acid (FA) profile of feeding dairy cows extruded linseed (EL), a feed rich in α-linolenic acid, and to assess the variability of the responses related to the dose of EL and the basal diet composition. This meta-analysis was carried out using only data from trials including a control diet without fat supplementation. The dependent variables were defined by the mean differences between values from EL-supplemented groups and values from control groups. The data were processed by regression testing the dose effect, multivariable regression testing the effect of each potential interfering factor associated with the dose effect, and then stepwise regression with backward elimination procedure with all potential interfering factors retained in previous steps. This entire strategy was also applied to a restricted data set, including only trials conducted inside a practical range of fat feeding (only supplemented diets with <60 g of fat/kg of dry matter and supplemented with <600 g of fat from EL). The whole data set consisted of 17 publications, representing 21 control diets and 29 EL-supplemented diets. The daily intake of fat from EL supplementation ranged from 87 to 1,194 g/cow per day. The dry matter intake was numerically reduced in high-fat diets. Extruded linseed supplementation increased milk yield (0.72 kg/d in the restricted data set) and decreased milk protein content by a dilutive effect (-0.58 g/kg in the restricted data set). No effect of dose or diet was identified on dry matter intake, milk yield, or milk protein content. Milk fat content decreased when EL was supplemented to diets with high proportion of corn silage in the forage (-2.8 g/kg between low and high corn silage-based diets in the restricted data set) but did not decrease when the diet contained alfalfa hay. Milk trans-10 18:1 proportion increased when EL was supplemented to high corn silage-based diets. A shift in ruminal biohydrogenation pathways, from trans-11 18:1 to trans-10 18:1, probably occurred when supplementing EL with high corn silage-based diets related to a change in the activity or composition of the microbial equilibrium in the rumen. The sum of pairs 4:0 to 14:0 (FA synthesized de novo by the udder), palmitic acid, and the sum of saturated FA decreased linearly, whereas oleic acid, vaccenic acid, rumenic acid, α-linolenic acid, and the sums of mono- and polyunsaturated FA increased linearly when the daily intake of fat from EL was increased. In experimental conditions, EL supplementation increased linearly proportions of potentially human health-beneficial FA in milk (i.e., oleic acid, vaccenic acid, rumenic acid, α-linolenic acid, total polyunsaturated FA), but should be used cautiously in corn silage-based diets.

Effect of oilseed type on milk fatty acid composition of individual cows, and also bulk tank milk fatty acid composition from commercial farms

Supplementing dairy cow diets with oilseed preparations has been shown to replace milk saturated fatty acids (SFA) with mono- and/or polyunsaturated fatty acids (MUFA, PUFA), which may reduce risk factors associated with cardio-metabolic diseases in humans consuming milk and dairy products. Previous studies demonstrating this are largely detailed, highly controlled experiments involving small numbers of animals, but in order to transfer this feeding strategy to commercial situations further studies are required involving whole herds varying in management practices. In experiment 1, three oilseed supplements (extruded linseed (EL), calcium salts of palm and linseed oil (CPLO) and milled rapeseed (MR)) were included in grass silage-based diets formulated to provide cows with ~350 g oil/day, and compared with a negative control (Control) diet containing no supplemental fat, and a positive control diet containing 350 g/cow per day oil as calcium salt of palm oil distillate (CPO). Diets were fed for 28-day periods in a 5×4 Latin Square design, and milk production, composition and fatty acid (FA) profile were analysed at the end of each period. Compared with Control, all lipid supplemented diets decreased milk fat SFA concentration by an average of 3.5 g/100 g FA, by replacement with both cis- and trans-MUFA/PUFA. Compared with CPO, only CPLO and MR resulted in lower milk SFA concentrations. In experiment 2, 24 commercial dairy farms (average herd size±SEM 191±19.3) from the south west of the United Kingdom were recruited and for a 1 month period asked to supplement their herd diets with either CPO, EL, CPLO or MR at the same inclusion level as the first study. Bulk tank milk was analysed weekly to determine FA concentration by Fourier Transform mid-IR spectroscopy prediction. After 4 weeks, EL, CPLO and MR all decreased herd milk SFA and increased MUFA to a similar extent (average -3.4 and +2.4 g/100 g FA, respectively) when compared with CPO. Differing responses observed between experiments 1 and 2 may be due in part to variations in farm management conditions (including basal diet) in experiment 2. This study demonstrates the importance of applying experimental research into commercial practice where variations in background conditions can augment different effects to those obtained under controlled conditions.

Effects of extruding wheat dried distillers grains with solubles with peas or canola meal on ruminal fermentation, microbial protein synthesis, nutrient digestion, and milk production in dairy cows

Our objective was to examine the effects of feeding coextruded and nonextruded supplements consisting of wheat dried distillers grains with solubles with peas (WDDGS-peas) or canola meal (WDDGS-CM) on ruminal fermentation, omasal flow, and production performance in Holstein cows. Eight cows (4 ruminally cannulated) were used in a replicated 4×4 Latin square with 28-d periods and a 2×2 factorial arrangement of dietary treatments. Dietary treatments were coextruded or nonextruded mixtures of WDDGS-peas and WDDGS-CM that were included in total mixed rations at 15.1% [dry matter (DM) basis]. Diet had no effect on DM intake. Milk yield was greater in cows fed coextruded diets compared with those fed nonextruded diets. Milk fat content was greater in cows fed nonextruded diets compared with those fed coextruded diets, but milk fat yield was greater in cows fed coextruded diets compared with those fed nonextruded diets. Milk yield tended to be greater and milk protein yield was greater in cows fed WDDGS-peas compared with those fed WDDGS-CM. Cows fed nonextruded diets had a greater milk urea-N concentration compared with those fed coextruded diets. Cows fed coextruded diets had greater ruminal digestion of DM and tended to have greater ruminal digestion of organic matter compared with those fed nonextruded diets. Total-tract digestibilities of organic matter, crude protein, ether extract, and starch were greater, whereas that of acid detergent fiber and neutral detergent fiber tended to be greater in cows fed coextruded compared with those fed nonextruded diets. Total-tract digestibility of ether extract was lower whereas that of starch was greater and that of crude protein tended to be greater in cows fed WDDGS-peas compared with those fed WDDGS-CM. Total N excretion and milk N efficiency were unaffected by diet. Ruminal NH3-N concentration tended to be greater in cows fed WDDGS-CM compared with those fed WDDGS-peas. Ruminal propionate concentration was greater whereas plasma urea-N concentration tended to be lower in cows fed coextruded compared with those fed nonextruded diets. Plasma glucose concentration was greater in cows fed diets containing WDDGS-CM compared with those fed diets containing WDDGS-peas, but the difference in plasma glucose concentration between WDDGS-CM and WDDGS-peas was greater in cows fed coextruded diets compared with those fed nonextruded diets. In summary, feeding coextruded compared with nonextruded supplements or WDDGS-peas compared WDDGS-CM increased yields of milk, fat, and protein.

Effect of dietary crude protein and forage contents on enteric methane emissions and nitrogen excretion from dairy cows simultaneously

The study aimed to examine, simultaneously, the effects of changing dietary forage and crude protein (CP) contents on enteric methane (CH4) emissions and nitrogen (N) excretion from lactating dairy cows. Twelve post-peak lactating Holstein cows (157 ± 31 days postpartum; mean ± s.d.) were randomly assigned to four treatments from a 2 × 2 factorial arrangement of two dietary forage levels [37.4% (LF) vs 53.3% (HF) of DM] and two dietary CP levels [15.2% (LP) vs 18.5% (HP) of DM] in a 4 × 4 Latin square design with four 18-day periods. Alfalfa hay was the sole source of dietary forage. Cows were fed ad libitum and milked twice daily. During the first 14 days, cows were housed in a free-stall barn, where enteric CH4 emissions were measured using the GreenFeed system from Days 8 to 14 in each period. Cows were then moved to metabolic cages, where faeces and urine output (kg/cow.day) were measured by total collection from Days 16 to 18 of each period. No dietary forage by CP interactions were detected for DM intake, milk production, enteric CH4 emissions, or N excretions. There was a tendency for DM intake to increase 0.6 kg/day in cows fed LF (P = 0.06). Milk production increased 2.1 kg/day in LF compared with HF (P < 0.01). Milk fat content decreased in cows fed LF compared with HF (1.07 vs 1.17 kg/day; P < 0.01). Milk contents of true protein, lactose and solid non-fat were greater in cows fed LF (P < 0.01). No difference in DM intake, milk yield and milk contents of true protein, lactose and solid non-fat was found between cows fed HP or LP. However, milk fat content increased 0.16 kg/day in cows fed HP (P < 0.05). Enteric CH4 emissions, and CH4 per unit of DM intake, energy-corrected milk, total digested organic matter and neutral detergent fibre were not affected by dietary CP, but decreased by LF compared with HF (P < 0.01). Milk true protein N was not affected by dietary CP content but was higher for LF compared with HF. Dietary N partitioned to milk true protein was greater in cows fed LF compared with HF (29.4% vs 26.7%; P < 0.01), also greater in cows fed LP compared with HP (30.8% vs 25.2%; P < 0.01). Dietary N partitioned to urinary N excretion was greater in cows fed HP compared with LP (39.5% vs 29.6%; P < 0.01) but was not affected by dietary CP content. Dietary N partitioned to faeces was not affected by dietary CP but increased in cows fed LP compared with HP (34.2% vs 27.8%; P < 0.01). Total N excretion (urinary plus faecal) as proportion to N intake did not differ between HP and LP, but tended to be lower in cows fed LF compared with the HF diet (64.2% vs 67.9%; P = 0.09). Both milk urea N (P < 0.01) and blood urea N (P < 0.01) declined with decreasing dietary CP or forage contents. Based on purine derivative analysis, there was a tendency for interaction between dietary CP and forage content on microbial protein synthesis (P < 0.09). Rumen microbial protein synthesis tended to be lower for high forage and low protein treatments. Increasing dietary forage contents resulted in greater CH4 emission (g/kg of energy-corrected milk) and manure N excretion (g/kg of energy-corrected milk) intensities of lactating dairy cows. Cows receiving reduced CP diets had low manure N outputs and improved milk true protein production efficiencies, regardless of dietary forage content.

Concentrate: forage ratio in the diet of dairy cows does not alter milk physical attributes

This study aimed to evaluate the effect of concentrate-to-forage ratio (C:F) on the performance, blood profile, and milk physicochemical characteristics of mid-lactation cows fed a corn silage-based diet. Twenty four Holstein cows, with BW 575 ± 70 kg, body condition score (BCS) 3.1 ± 0.2, milk yield 18.4 ± 3.0 kg, and days in milk (DIM) 121 ± 21 were randomly allocated into three treatments with C:F ratios of 35:65, 45:55, and 55:45 on a dry matter (DM) basis. Data was submitted to analyses of variance and regression. Increasing C:F from 35 to 55 % linearly enhanced milk production (22 to 23.6 kg day(-1)) and serum urea nitrogen (16.8 to 19.6 mg/dL), while it linearly reduced lactose and fat in milk (4.8 to 4.6 %; 3.9 to 3.6 %, respectively). Body weight, BCS, milk acidity, ethanol stability, coagulation time, and milk and blood mineral contents did not differ among treatments. During the last period of measurements, increased C:F reduced urinary pH and milk urea nitrogen. Changes of concentrate-to-forage proportion from 35 to 55 % increased milk yield, altered chemical composition without changing BW, BCS, acidity, stability, and mineral content of milk and blood attributes.

Effect of feeding extruded flaxseed with different grains on the performance of dairy cows and milk fatty acid profile

Sixteen Holsteins cows were used in a Latin square design experiment to determine the effects of extruded flaxseed (EF) supplementation and grain source (i.e., corn vs. barley) on performance of dairy cows. Extruded flaxseed diets contained 10% [dry matter (DM) basis] of an EF product that consisted of 75% flaxseed and 25% ground alfalfa meal. Four lactating Holsteins cows fitted with rumen fistulas were used to determine the effects of dietary treatments on ruminal fermentation. Intakes of DM (23.2 vs. 22.2 kg/d), crude protein (4.2 vs. 4.0 kg/d), and neutral detergent fiber (8.3 vs. 7.9 kg/d) were greater for cows fed EF diets than for cows fed diets without EF. Milk yield and composition were not affected by dietary treatments. However, 4% fat-corrected milk (30.5% vs. 29.6 kg/d) and solids-corrected milk (30.7 vs. 29.9 kg/d) were increased by EF supplementation. Ruminal pH and total volatile fatty acid concentration were not influenced by EF supplementation. However, feeding barley relative to corn increased molar proportions of acetate and butyrate and decreased that of propionate. Ruminal NH3-N was lower for cows fed barley than for cows fed corn. Milk fatty acid composition was altered by both grain source and EF supplementation. Cows fed EF produced milk with higher polyunsaturated and lower saturated fatty acid concentrations than cows fed diets without EF. Feeding EF or corn increased the milk concentration of C18:0, whereas that of C16:0 was decreased by EF supplementation only. Extruded flaxseed supplementation increased milk fat α-linolenic acid content by 60% and conjugated linoleic acid content by 29%. Feeding corn relative to barley increased milk conjugated linoleic acid by 29% but had no effect on milk α-linolenic concentration. Differences in animal performance and milk fatty acid composition were mainly due to EF supplementation, whereas differences in ruminal fermentation were mostly due to grain source.