Pasture Dry Matter Intake Research Articles

Effect of Replacing Corn Grain and Soybean Meal with Field Peas at Different Levels on Feed Intake, Milk Production, and Metabolism in Dairy Cows under a Restrictive Grazing.

This study assessed the effects of replacing soybean meal (SBM) and corn grain with field peas in the concentrate of grazing dairy cows on milk production, intake, ruminal fermentation, and blood indicators. Twelve multiparous lactating Holstein-Friesian cows were utilized in a replicated 3 × 3 Latin square design, comprising three periods and three treatments: (1) Pea-0 (Control diet): 6 kg dry matter (DM) of fresh pasture, 7.2 kg DM of grass silage, and 7 kg DM of a concentrate containing 0% pea; (2) Pea-30: Control diet with the concentrate composed of 30% pea; (3) Pea-60: Control diet with the concentrate composed of 60% pea. The effect of treatments on productive and metabolic parameters was evaluated using linear-mixed models. Pasture and total DM intake, milk production, and composition were unaffected by treatments. Despite the concentrates being isonitrogenous and isoenergetic, crude protein (CP) intake was slightly higher in Pea-30 and significantly higher in Pea-60 due to higher pasture CP content in the pasture grazed by these groups, leading to higher milk urea content, though within recommended ranges. Blood parameters showed no significant changes, except for plasma β-hydroxybutyrate, which was lowest in the Pea-60 treatment; however, all values were within ranges not indicative of subclinical ketosis. Ruminal fermentation parameters were similar across treatments. These findings support the use of field peas as a viable alternative to replace SBM and corn grain in concentrates, enabling similar milk production and composition in grazing dairy cows.

Effect of Particle Size of Silage of Flint Corn Grain on Dairy Cows Fed Tropical Pasture: Performance, Intake, Ruminal Fermentation, and Digestibility.

The particle size (PS) of reconstituted corn (REC) can affect the grinding rate and starch digestibility in dairy cows. We evaluated the effect of the PS of REC ensiled for 40 days on the pasture dry matter intake (DMI), lactation performance, total tract digestibility, and ruminal fermentation of grazing dairy cows. The treatments were coarse REC (CO, 1694 µm), fine REC (FI, 1364 µm), or finely ground (GC, 366 µm) flint corn (68% vitreousness) at 29.6 ± 1.4% of diet DM (mean ± SD). Eighteen dairy cows (mean milk yield 21.3 kg/d) were split into three groups by production level and were assigned within each group to a sequence of treatments in 3 × 3 Latin squares of 21-day periods. Cows were individually fed a constant amount of whole-plant corn silage 3 ×/d (2.7 kg DM/d) and corn treatments and soybean meal according to their group. There was no significant interaction between treatment and the production level. Cows fed FI had a lower DMI (16.7 vs. 18.1 kg/d) than those fed GC, and both did not differ from CO (17.7 kg/d). There was no treatment effect on milk yield (mean: 19.2 kg/d). Cows fed CO had the lowest total tract digestibility of starch (86.3 vs. 92.3% of intake) and the highest fecal starch concentration (7.0 vs. 4.0% of DM). The NDF digestibility was lower for GC-fed cows than CO- and FI-fed cows. Plasma glucose was higher in cows fed FI and CO (75.0 mg/dL) than those fed GC (70.8 mg/dL). Ruminal volatile fatty acids and the pH did not differ. Fine grinding of REC increased the feed efficiency relative to CO and GC. Coarse grinding of REC ensiled for 40 days reduced the total tract starch digestibility relative to FI and GC.

Enteric Methane Emissions in Dairy Cows with Different Genetic Groups in the Humid Tropics of Costa Rica

Enteric methane (CH4) is one of the main greenhouse gases emitted in livestock production systems with ruminants. Among the options to reduce such emissions, animal genetics is one of the factors that is taking relevance in recent years. The aim of the present study was to assess the emission of enteric CH4 in dairy cows with different genetic backgrounds. Sixteen cows belonging to the following three genetic groups were selected for this study: seven F1 (50% Jersey × 50% Gyr), five Triple cross (50% Jersey × 31% Holstein × 19% Sahiwal) and four Jersey. Enteric CH4 emissions were measured in all cows for 15 months, at the middle of each month, using the SF6 technique. Enteric CH4 emissions did not differ (p > 0.05) among genetic groups, although it varied with the stage of lactation, due to differences in milk yield and dry matter intake (DMI). Pasture DMI and the intensity of CH4 emissions (g kg-1 DMI) differed (p < 0.05) between dry and lactating cows, with higher DMI in the lactation period, while CH4 emission intensity was higher for dry cows. Cows with the highest proportion of Bos taurus genes presented a higher annual mean methane conversion factor (Ym), with 7.22, 7.05 and 5.90% for the Triple cross, purebred Jersey and F1, respectively. In conclusion, non-significant differences in enteric CH4 emissions and Ym were detected among dairy cows with different genetic backgrounds. However, F1 cows tended to show lower enteric CH4 emission and Ym, compared to those with more Bos taurus genes.

Effects of Sugar Beet Silage, High-Moisture Corn, and Corn Silage Feed Supplementation on the Performance of Dairy Cows with Restricted Daily Access to Pasture.

Simple SummarySeasonal variations in herbage growth rate and nutrient composition result in low herbage intake which is insufficient to meet the nutritional requirements of cows and limits milk production. The main opportunities for increasing milk production per cow and per ha are a careful pasture management to ensure adequate herbage high-quality and strategic low-cost and high-energy feed supplementation. Supplementation strategies include different combinations of level, type, and processing of supplemental feeds. This study evaluates the effect of supplementation with sugar beet silage, corn silage, or high-moisture corn (HMC) on dairy performance, rumen, and plasma metabolites in dairy cows under conditions of restricted grazing in spring. We found that the supplementation with sugar beet silage allowed milk production, live weight, and fat concentration similar to corn silage and HMC, but with a lower concentration of milk protein than HMC. Results suggest that sugar beet silage can be used as an alternative supplement for high-producing dairy cows under conditions of restricted grazing in the current experiment.A study was undertaken to assess the effect of supplementation with sugar beet silage, corn silage, or high-moisture corn on dairy performance, rumen, and plasma metabolites in dairy cows under conditions of restricted grazing in spring. Eighteen multiparous Holstein Friesian cows, stratified for milk yield (39.4 kg/day ± 3.00), days of lactation (67.0 days ± 22.5), live weight (584 kg ± 38.0), and number of calves (5.0 ± 1.5), were allocated in a replicated 3 × 3 Latin square design. Treatments were as follows: SBS (10 kg DM of permanent pasture, 7 kg DM of sugar beet silage, 4 kg DM of concentrate, 0.3 kg DM of pasture silage, 0.21 kg of mineral supplement); corn silage (10 kg DM of permanent pasture, 7 kg DM of corn silage, 4 kg DM of concentrate, 0.3 kg DM of pasture silage, 0.21 kg of mineral supplement), and HMC (10 kg DM of permanent pasture, 5 kg DM of high-moisture corn, 4.5 kg DM of concentrate, 1.2 kg DM of pasture silage, 0.21 kg of mineral supplement). Pasture was offered rotationally from 9 a.m. to 4 p.m. Between afternoon and morning milking, the cows were housed receiving a partial mixed ration and water ad libitum. The effect of treatments on milk production, milk composition, body weight, rumen function, and blood parameters were analyzed using a linear–mixed model. Pasture dry matter intake (DMI) was lower in SBS than CS (p < 0.05) and similar to HMC, but total DMI was higher in HMC than SBS (p < 0.05) and similar to CS. Milk production for treatments (32.6, 31.7, and 33.4 kg/cow/day for SBS, CS, and HMC, respectively), live weight, and fat concentration were not modified by treatments, but milk protein concentration was lower for SBS compared with HMC (p < 0.05) and similar to CS. B-hydroxybutyrate, cholesterol, and albumin were not different among treatments (p > 0.05), while urea was higher in SBS, medium in CS silage, and lower in HMC (p < 0.001). Ruminal pH and the total VFA concentrations were not modified by treatments (p > 0.05), which averaged 6.45 and 102.03 mmol/L, respectively. However, an interaction was observed for total VFA concentration between treatment and sampling time (p < 0.05), showing that HMC produced more VFA at 10:00 p.m. compared with the other treatments. To conclude, the supplementation with sugar beet silage allowed a milk response and composition similar to corn silage and HMC, but with a lower concentration of milk protein than HMC. In addition, sugar beet silage can be used as an alternative supplement for high-producing dairy cows with restricted access to grazing during spring.

Effects of concentrate supplementation and genotype on milk production and nitrogen utilisation efficiency in late-lactation, spring-calving grazing dairy cows

The study objectives were to evaluate the effects of (1) concentrate supplementation (CS), (2) cow genotype, and (3) a potential interaction between CS and cow genotype on milk production, dry matter (DM) intake (DMI) and cow nitrogen (N) utilisation efficiency (NUE) in late lactation (+208 ± 14.1 days in milk), spring-calving grazing dairy cows. The experiment was a complete randomised block design with a 2 × 2 factorial arrangement of treatments and was conducted over a 52-day period. There were two feeding strategies (pasture-only (PO) and pasture + 2.7 kg DM CS) and two genotype groups [lower milk genotype (LM; milk kg PTA = -48 ± 59.9, fat kg PTA = +7 ± 4.7 and protein kg PTA = +3 ± 3.2) and higher milk genotype (HM; milk kg PTA = +190 ± 109.7, fat kg PTA = +12 ± 5.7 and protein kg PTA = +9 ± 3.6)]. Cows in their respective genotype group were randomly assigned to one of two feeding strategies, resulting in four treatment groups (n = 12). Cows grazed full time and were allocated 17 kg DM pasture/cow per d. No interactions were observed for any parameters measured. Cows offered CS had increased daily yields of fat + protein (+0.18 kg), lactose (+0.13 kg) and ECM (+2.46 kg) compared to cows offered PO. The HM cows had increased yields of daily fat + protein (+0.13 kg) and lactose (+0.1 kg) compared to the LM cows. Cows offered CS had decreased daily protein (-0.14%) but increased lactose (+0.08%) concentration compared to cows offered PO. The HM cows had decreased daily fat (-0.2%), protein (-0.16%) and casein (-0.07%) concentration compared to the LM cows. Cows offered CS had a reduced daily pasture DMI (-1.41 kg) but an increased daily total DMI (+1.29 kg) and feed N intake (+0.085 kg) compared to cows offered PO. Cows offered CS had decreased NUE (-0.1%) compared to cows offered PO. In conclusion, offering cows 2.7 kg DM CS per day improved milk production in late lactation but resulted in a poorer NUE. The poorer NUE was due to no difference in milk N output and an increase in the partitioning of feed N to urine. The HM cows had an increased milk response to CS with respect to milk fat + protein kg compared to the MR obtained from LM cows.

Holstein strain affects energy and feed efficiency in a grazing dairy system

Context Improving the partitioning of the energy consumed by dairy cows towards milk-solid production is a priority in grazing diary systems because energy efficiency has been associated with sustainability. Different selection criteria in the Holstein breed have led to divergent Holstein strains with different suitability to grazing systems. Aim The objective of this work was to quantify and evaluate the energy partitioning between maintenance and milk production of two divergent Holstein strains (New Zealand Holstein and North American Holstein) in a grazing system without supplementation of concentrate. Methods New Zealand Holstein and North American Holstein cows, nine of each, in mid-lactation (183 ± 37 days in milk, mean ± s.d.) were allocated in a randomised block design and evaluated under grazing conditions. The cows were managed under a daily strip-grazing system and grazed perennial ryegrass as the only source of nutrients. After an adaptation period of 14 days, heat production, retained energy in milk and metabolisable energy intake were measured over 7 days, and animal behaviour was simultaneously recorded. Key results Milk yield did not differ between Holstein strains, but fat and protein content were greater for New Zealand than North American Holstein cows; consequently, retained energy in milk was 13% greater for the former strain. Heat production did not differ between Holstein strains, but metabolisable energy intake (kJ/bodyweight0.75.day) was greater for New Zealand than North American Holstein cows, which was associated with a greater pasture dry matter intake relative to their body weight. Both feed and energy efficiency were greater for New Zealand than North American Holstein cows. Conclusions The results supported that the New Zealand Holstein strain has greater energy and feed efficiency, demonstrating that it could be more suitable to be managed under a grazing dairy system without supplementation than the North American Holstein strain. Implications The New Zealand Holstein strain may be suited to selection as a dairy cow with the capacity to fulfil energy requirements from pasture, which is a key factor to improve production efficiency of grazing dairy systems.

Prediction of pasture intake by beef cattle in tropical conditions

Forage intake is the most important factor for beef cattle raised on pasture, as it is the basis of the diet. Thus, knowing the variables that affect this parameter can help supplementation programs. Thus, a meta-analytic study was conducted to develop and evaluate models for the prediction of pasture dry matter intake (DMIpasture) by beef cattle in tropical conditions. Eight hundred four individual observations of DMIpasture were used, taken from 23 studies through analysis of mixed models, including the study as a random effect. To evaluate the accuracy and precision of the new models proposed as well as for the models of Azevedo et al. (2016) and Minson and McDonald (1987), an independent databank with 87 means from treatments of 21 experiments (n = 888 animals) was used. Three prediction models were adjusted: model I (animal information), model II (animal information + supplement), and model III (animal information + supplement + pasture). The proposed models presented similarity for the average square root of the prediction error. The inclusion of the predictive variables for supplementation (supplement dry matter intake - DMIsupplement - % of the body weight and crude protein intake through supplement) with the variables for the animal (BW0.75 and average daily gain) and of the pasture (% of crude protein) in model III improved accuracy and precision and provided higher determination and correlation coefficients, and agreement than the other proposed models. Similarly, it was found to be more accurate and precise than the equations of Azevêdo et al. (2016) and Minson and McDonald (1987), which presented lower precision. The DMIpasture for beef cattle in tropical conditions is more accurate and precise when the information for the animal, supplement, and pasture is included.

PSVII-13 Performance and environmental benefits from biochar supplementation in beef cattle grazing systems

Abstract Worldwide, beef production systems represent a significant source of greenhouse gas (GHG), and enteric methane (CH4) emissions are the primary concern. The objective of this experiment was to determine whether biochar (Oregon Biochar Solution, White City, OR) supplementation can reduce CH4 emissions from grazing beef cows. Biochar is a stable form of carbon produced through the pyrolysis of organic matter (typically forestry waste). Sixty-four cows and their calves were blocked by cow body weight and calf age, and randomly allocated to 8 paddocks, each with 8 cow-calf pairs. Using a crossover design, each paddock was assigned to one of two treatments: (1) biochar supplemented at approximately 3% of estimated dry matter intake (DMI) or (2) control (no biochar). Biochar was incorporated into a pellet containing 45% biochar, 42.5% wheat midds, 10% canola oil, and 2.5% dry molasses and fed in a portable trough once daily. Each period consisted of 28 days: 21 days for biochar adaptation and 7 days for data collection. Enteric gas emissions from each paddock were measured using C-Lock GreenFeed trailers (C-Lock Inc., Rapid City, SD, USA) with pasture DMI estimated using paddock entry/exit quadrats during each sampling week. Enteric CH4 emissions expressed as g CH4/d were 249 and 260 ± 50.3 g (P ≥ 0.37) for control and biochar, respectively. Similarly, g CH4/kg DM and g CH4/kg BW were not affected (P ≥ 0.44) by biochar supplementation on pasture. Biochar supplementation did not affect estimated DMI or cow/calf body weights (P ≥ 0.15). Results suggest that biochar was ineffective for reducing methane emissions from grazing beef cows; however, measures of animal performance were not affected by biochar consumption. Further work is required to determine if type or higher inclusions of biochar can reduce CH4 emissions from beef cattle.

Strip-grazing: Reduces pony dry matter intakes and changes in bodyweight and morphometrics.

Obesity can negatively impact upon equine welfare and bodyweight (BW) of pastured equines is often difficult to manage. To compare the effects of three restricted grazing regimens on changes in pony BW and morphometric measurements. Randomised study. Twelve mature ponies were individually grazed in 10m wide, rectangular, electric fenced paddocks. The dry matter (DM) herbage yield of each paddock was determined, and paddock length adjusted on Day 1 to provide 1.5% of individual pony BW as herbage DM daily, for 28days. There were four ponies per treatment. Treatments were: total paddock area (TA) and strip grazing treatments, SG1 and SG2. SG1 had a 'lead' fence spanning the paddock width being moved a set distance along the paddock length daily to provide 1.5% of pony BW as fresh pasture DM (as determined on Day -1). SG2 also had a 'back fence' 7-12m behind the 'lead' fence which was moved the same distance as the lead fence daily. Calculated dry matter intakes, changes in cresty neck score (CNS), body condition score (BCS) and percentage changes in BW, heart girth (HG), belly girth (BG) and rump width (RW) were compared between treatments. Mean (±SD) calculated pasture DM intakes (as % BW/d) by TA ponies were 2.33±0.50, being significantly higher (P< 0.05) than 1.82±0.43 (SG1) and 1.59±0.42 (SG2). Mean percentage BW changes were higher (P<0.05) for TA ponies at 4.82±1.36 vs. 1.16±0.39 (SG1) and 1.54±1.35 (SG2). SG1 and SG2 pony BW changes were not significantly different. TA, but not SG1 or SG2 animals showed significant (P<0.05) increases in BCS1/9 (+0.94±0.32), CNS1/5 (+0.5±0), RW (+2.11±3.6) and BG (+4.15±2.29). SG1 and SG2 ponies showed significant (P<0.05) decreases in HG (-0.05±2.12) and BG (-5.53±4.89) respectively. Small sample size. Strip grazing limited pony bodyweight gains and upward changes in morphometric parameters.

Effects of grain-based concentrate feeding and rumination frequency on the milk production, methane and carbon dioxide fluxes, and activity of dairy cows in a pasture-based automatic milking system

The warming effect of ruminant greenhouse gases is an issue of increasing global concern. In this experiment the abatement of ruminant gases by offering three levels of grain-based concentrate (GBC) to dairy cows of high and low rumination frequency was tested in a pasture-based, automatic milking system. Two groups of 30 cows (milk yield = 35 ± 2 kg/d), with consistently high (HR; 619.9 ± 8.9 min/d) or low (LR; 472.5 ± 10.2 min/d) rumination frequency were selected and assigned to either a low (LGBC), medium (MGBC) or high (HGBC) grain-based concentrate feeding treatment (n = 10 cows/treatment) that included a standard grain-based pellet ration of 7 kg DM/cow/d plus 0, 1.5 or 3 kg DM/cow/d of shelled corn, respectively. Cows on all treatments were also offered the same temperate pasture at 30 kg DM/cow/d that was split evenly between two fresh pasture breaks. Milk production, rumination frequency, activity, mass flux of enteric methane (QCH4) and expired carbon dioxide (QCO2), and dry matter intake (DMI), determined empirically by use of QCO2 as a biomarker, were recorded for 12 d and analysed with mixed models for a completely randomised design. No effect of rumination on QCH4 or QCO2 was detected. Offering HGBC decreased (P = 0.02) DMI and QCO2. Offering HGBC also reduced (P < 0.001) pasture DMI, and this decrease was associated with a lower (P = 0.03) DMI/activity. Both the intensity of QCH4/milk and QCO2/milk decreased exponentially with increasing milk yield, supporting a dilution effect as more feed energy was sequestered in milk. Feeding a composite GBC between 7 to 10 kg altered the activity and grazing patterns of cows, but had only a marginal change on total QCH4, probably because the effects of GBC plateaued beyond the feeding of 7 kg DM/cow/d of GBC. A broader life cycle analysis including wider ranges for GBC feeding levels at different lactation stages must be considered before providing conclusive recommendations on ruminant dietary manipulations for greenhouse gas abatement.

Feed Intake, Methane Emissions, Milk Production and Rumen Methanogen Populations of Grazing Dairy Cows Supplemented with Various C 18 Fatty Acid Sources.

Simple SummaryReducing methane emissions from dairy cows is environmentally important. In this experiment, pasture fed dairy cows offered concentrates containing linseed oil emitted 18% less methane per kg of milk solids produced than those offered concentrates containing either stearic acid or soy oil. Additionally, cows fed linseed oil or soy oil produced more milk than those fed stearic acid. These results may contribute to the development of strategies to reduce methane emissions from pasture-based livestock whilst maintaining or improving animal productivity.Emissions of methane (CH4) from dairy production systems are environmentally detrimental and represent an energy cost to the cow. This study evaluated the effect of varying C18 fatty acid sources on CH4 emissions, milk production and rumen methanogen populations in grazing lactating dairy cows. Forty-five Holstein Friesian cows were randomly allocated to one of three treatments (n = 15). Cows were offered 15 kg dry matter (DM)/d of grazed pasture plus supplementary concentrates (4 kg DM/d) containing either stearic acid (SA), linseed oil (LO), or soy oil (SO). Cows offered LO and SO had lower pasture DM intake (DMI) than those offered SA (11.3, 11.5 vs. 12.6 kg/d). Cows offered LO and SO had higher milk yield (21.0, 21.3 vs. 19.7 kg/d) and milk protein yield (0.74, 0.73 vs. 0.67 kg/d) than those offered SA. Emissions of CH4 (245 vs. 293, 289 g/d, 12.4 vs. 15.7, 14.8 g/kg of milk and 165 vs. 207, 195 g/kg of milk solids) were lower for cows offered LO than those offered SA or SO. Methanobrevibacter ruminantium abundance was reduced in cows offered LO compared to SA. Offering supplementary concentrates containing LO can reduce enteric CH4 emissions from pasture fed dairy cows.

Performance of lactating buffaloes in pasture supplemented with palm-kernel cake

Context Palm-kernel cake (PKC) is a by-product widely evaluated as a feed additive in several species of ruminant animals. However, no information of its use in buffaloes is observed. Thus, considering the characteristics of PKC and that buffaloes are able to digest greater amounts of fibre than are other animals, it is thought that PKC can be used as a supplement for lactating buffaloes in pasture. Aims The aim of the present study was to evaluate the effects of concentrate supplementation and the inclusion of PKC instead of conventional concentrate ingredients on the production and composition of milk, intake and nutrient digestibility of lactating buffaloes in pasture during the dry season. Methods Five crossbred buffaloes with average bodyweight of 641.45 ± 45.87 kg were used and distributed in a 5 × 5 Latin square-design experiment. The treatments consisted in one treatment with mineral salt supplementation (cows fed just forage; MSS control group), and four other treatments in which the cows grazed and received 3 kg/day of concentrated supplementation. The four treatments with concentrated supplementation had different inclusion levels of PKC as a supplement, which were 0%, 30.24%, 66.38% and 90.62% of dry matter (DM) replacing corn and soybean meal. A contrast between the treatment with mineral salt supplementation (MSS control group) versus the four treatments supplemented with concentrate was analysed. In addition, to analyse the effect of inclusion of PKC in the concentrate supplement, the linear and quadratic effects were analysed by decomposing the sum of squares of each level of inclusion of PKC. Key results There was no difference (P &amp;gt; 0.05) in pasture DM intake among the supplemented animals and the control-group animals (MSS). The supplemented animals (regardless of the level of inclusion of PKC) had higher (P &amp;lt; 0.05) fat-corrected milk production and a higher percentage of fat and lactose in the milk than did the MSS control-group animals. The intake of the supplement, crude protein and total digestible nutrients showed a decreasing linear effect (P &amp;lt; 0.05) with the inclusion of PKC. The daily milk production showed a decreasing linear effect (P &amp;lt; 0.05) with the inclusion of PKC in the concentrate. Conclusions Concentrate supplementation for lactating buffaloes in pasture increases the amount of fat in the milk and the production of energy-corrected milk. The inclusion of PKC in concentrate supplement, replacing corn and soybean meal, decreases supplement intake and milk production. Implications The data suggested that PKC reduced milk solids when replacing conventional concentrate ingredients; however, PKC supplements stimulated milk yield when compared with mineral salt supplementation (MSS control group). Therefore, if the inclusion of PKC reduces feeding costs, it is an economic source of supplement to promote milk production.

Milk Fatty-Acid Profile after Feeding Increasing Doses of a Mixture of Soybean and Linseed Oils to Pasture Dairy Cows

The goal was to determine the effect of growing intake of a mixture (75:25) of soybean (SoOi) and linseed (LiOi) oils on milk production and composition and milk fatty-acid (MF-A) profile in grazing dairy cows. Twenty-four Holstein cows were assigned to 4 treatments in a completely randomized design with three weeks of adaptation to oil doses and one week of experimental measurements. On a dry matter (DM) basis, cows were fed pasture (63%), energy concentrate (37%) and the SO-LO oil mixture at zero (Tr0%), 2% (Tr2%), 4% (Tr4%) and 6% (Tr6%) of total DM intake equivalent to 0, 0.36, 0.72 and 1.08 kg/cow/day of the oil mixture. The oil mixture was manually mixed-up to the concentrate (7.04 kg DM cow/day) and supplied by halves during each milking time without refusals. Pasture (P = 0.49) and total DM intakes (P = 0.31) were similar between treatments averaging 11.27 and 18.85 kg DM cow-1 day-1 respectively. Milk output (22.71 kg/cow/day) was not affected (P = 0.46). Milk fat content reduced linearly (P &lt; 0.05) from 3.20 (Tr0%) to 2.67 g 100 g-1 (Tr6%) without effects (P = 0.73) on fat or fat corrected milk (4%FCM) yields. Milk protein concentration (P &lt; 0.56) or yields (P &lt; 0.11 were not affected. Lactose contents tended (P &lt; 0.08) to be higher in oil supplemented cows and milk urea nitrogen was not affected (P = 0.14). The basal (Tr0%) concentration (g /100 g MF-A) of totaly hypercholesterolemic MF-A (C12:0, C14:0 and C16:0) of milk averaged 38.93 and decreased linearly (P &lt; 0.0001) with oil intake to 37.81 (Tr2%), 31.59 (Tr4%) and 29.18 (Tr6%). Levels of elaidic (trans-9 C18:1) and trans-10 C18:1 MF-A resulted low-slung in the basal (Tr0%) milk (0.21 and 0.20 g/100g MF-A, respectively) but increased linearly (P &lt; 0.0001) after oil intake reaching the maximum values at Tr6% (0.73 and 2.23 g/100g MF-A, respectively). Milk concentration (g/100g MF-A) of vaccenic acid (trans-11 C18:1, VA) averaged 3.63 in Tr0% and increased linearly (P &lt; 0.0001) with oil intake reaching 4.97, 7.05 and 8.38 in Tr2%, Tr4% and Tr6%, respectively. Basal concentration of rumenic acid (cis-9. trans-11 C18:2, RA) was 2.28 g/100g MF-A and increased linearly (P &lt; 0.0001) with increased oil dose resulting in maximal plateau in Tr4% (3.88) and Tr6% (3.89). The basal atherogenic index (AI) of milk was 1.87 and linearly decreased (P &lt; 0.01) to 1.64 (Tr2%), 1.18 (Tr4%) and 0.95 (T6%) after oil intake. The basal Ω6/Ω3 ratio (3.57) was no different (P &gt; 0.05) from T2% (3.37) but was upper (P &lt; 0.05) in Tr4% (4.41) and Tr6% (4.63) remaining under the recommended value of 5:1. Taken together the results suggest that feeding a blend (75:25; SoOi:LiOi) of SiOi an LiOi oils at 4% of total DM intake to pasture dairy cows maximize the milk RA content with a concomitant decrease in the hypercholesterolemic MF-A of milk maintaining a beneficial for health Ω6/Ω3 ratio with low levels of the detrimental trans-9 C18:1 and trans-10 C18:1.

Systematic Review and Meta-Analysis: Identification of Factors Influencing Milking Frequency of Cows in Automatic Milking Systems Combined with Grazing.

Simple SummaryNumerous publications have investigated the possibility of combining automatic milking systems (AMS) with grazing. Milking frequency (MF) was usually considered as an indicator of robot performance and researchers focused on ways to optimize it. It seems pertinent to compile the published results. By using principal component analysis, we discriminated four agricultural exploitation systems (clusters). These systems differed from low—less than two milkings per day—to MF similar to those recorded at barn (2.7 milkings/cow per day). The description of clusters allowed for the identification of parameters influencing MF: concentrate supply, minimum milking interval, pasture dry matter intake and stage of lactation. By pair-wise analysis, we quantified the relationship between each parameter and MF. In a second step, we identified the relationship between MF and milk production (MY). These analyses allowed us to understand in which context these parameters could be efficient. For example, concentrate supply in full grazing has limited efficiency but in early lactation, increases MF. High percentage of grazed grass in a cow’s diet seems to limit MF. The impact of MF on MY was confirmed. In conclusion, several strategies can be implemented to combine grazing and AMS with an impact on productivity and on production costs. More dairy farms (up to more than one in four in some countries) are equipped with automatic milking systems (AMS) worldwide. Because of the positive impacts of grazing, e.g., on animal welfare or on production costs, numerous researchers have published papers on the combination of AMS with grazing. However, pasture-based AMS usually causes a reduction in milking frequency (MF) compared to indoors systems. The objectives of this meta-analysis were to review publications on the impacts of pasture-based AMS on MF and mitigation strategies. First, data from 43 selected studies were gathered in a dataset including 14 parameters, and on which a Principal Component Analysis (PCA) was performed, leading to the description of four clusters summarizing different management practices. Multiple pairwise comparisons were performed to determine the relationship between the highlighted parameters of MF on milk yield (MY). From these different analyses, the relationship between MF and MY was confirmed, the systems, i.e., Clusters 1 and 2, that experienced the lowest MF also demonstrated the lowest MY/cow per day. In these clusters, grazed grass was an essential component of the cow’s diet and low feeding costs compensated MY reduction. The management options described in Clusters 3 and 4 allowed maintenance of MF and MY by complementing the cows’ diets with concentrates or partial mixed ration supplied at the AMS feeding bin or provided at barn. The chosen management options were closely linked to the geographical origin of the papers indicating that other factors (e.g., climatic conditions or available grasslands) could be decisional key points for AMS management strategies.

Nutrient Intake, Excretion and Use Efficiency of Grazing Lactating Herds on Commercial Dairy Farms.

Simple SummaryExcess nutrients on dairy farms can affect soil and animal health and have negative impacts on the environment. More nutrients are usually brought onto farms in animal feed than in fertilizer and, as dairy cows do not efficiently use feed nutrients to produce milk, most consumed nutrients are excreted in dung and urine. Estimating nutrients excreted by cows relies on measuring feed and nutrient intake. However, measuring pasture nutrients consumed by cows that graze on commercial farms is complicated. We modified the ‘Feeding Standards’ approach to estimate daily pasture dry matter and nutrient intake and nutrients excreted using data and samples readily available on commercial dairy farms. These data were collected on five visits in different seasons from 43 grazing system farms located in diverse climatic zones. Although these herds graze daily, the lactating cows only obtained slightly more than half their dry matter intake from pasture. Each day, on average, we estimated that a grazing cow excretes 433 g nitrogen, 61 g phosphorus, 341 g potassium, 44 g sulphur, 92 g calcium and 52 g magnesium on these farms. Using this approach to estimate nutrients excreted by grazing animals on dairy farms can assist farmers improve nutrient distribution and fertilizer requirements.Estimating excreted nutrients is important for farm nutrient management, but seldom occurs on commercial grazing system farms due to difficulties in quantifying pasture intake. Nitrogen (N), phosphorus (P), potassium (K), sulphur (S), calcium (Ca) and magnesium (Mg) intake, excretion and use efficiency of 43 commercial dairy herds grazing pasture were calculated to understand the range in nutrient intake and excretion in these systems. Milk production, feed (grazed and supplement), as well as farm and herd management data were collected quarterly on representative farms located in temperate, arid, subtropical and tropical regions of Australia. Lactating herd sizes on these farms averaged 267 (30 to 1350) cows, with an average daily milk yield of 22 (9 to 36) kg/cow per day and the herds walked from <0.01 to 4 km/day on a variety of terrains. The mean total metabolizable energy (ME) required by cows in the herds was estimated to be 195 (116 to 289) MJ/cow per day. Although these farms are considered grazing systems, feeding strategies ranged from total dependence on pasture to total mixed rations (TMRTMR) and consisted of a wide variety of nutrient and energy contents. Mean pasture dry matter intake (DMI) (9 kg/cow per day, from 0.1 to 22 kg/cow per day) was just over half of total DMI. Dietary concentration of crude protein, P, K, S, Ca and Mg concentrations were, on average, 19%, 0.45%, 2.1%, 0.29%, 0.65%, and 0.3%, respectively, for all herds and, except for N, supplement nutrient concentrations were always more variable than pasture. Approximately 72% and 88% of diets provided greater than recommended P and N intakes, respectively. Calculated mean N, P, K, S, Ca and Mg excretions were 433, 61, 341, 44, 92 and 52 g/cow per day, respectively. Of the farm characteristics examined, residual maximum likelihood (REML) analysis indicated that daily excreted N, P and S were significantly related to per ha milk production, and excreted P, K and Mg were related to percentage of herd DMI provided as supplement. Mean use efficiencies by cows of N, P, K, S, Ca and Mg were 21%, 25%, 9%, 16%, 23% and 4%, respectively. These estimates of nutrient excretion and feed nutrient use efficiencies can be used to improve nutrient management on grazing system commercial dairy farms.

Pasture dry matter intake per cow in intensive dairy production systems: effects of grazing and feeding management

The competitiveness and sustainability of low input cost dairy production systems are generally supported by efficient use of pasture in the diets. Therefore, pasture intake directly affects overall efficiency of these systems. We aimed to assess feeding and grazing management main factors that affect pasture dry matter intake (DMI) in commercial dairy farms during the different seasons of the year. Fortnightly visits to 28 commercial dairies were carried out between June 2016 and May 2017 to record production and price, supplement offered and price, pasture access time (PAT), herbage mass (HM) and allowance (HA). Only farms with the most contrasting estimated pasture DMI per cow (eDMI) were compared as systems with high (HPI; N = 8) or low (LPI; N = 8) pasture DMI. Despite a lower individual milk production in HPI than LPI (19.0 v. 23.3 ± 0.7 l/cow, P < 0.01), daily margin over feeding cost was not different between groups (3.07 v. 2.93 ± 0.15 U$S/cow for HPI and LPI, respectively). During autumn and winter, HPI cows ingested more pasture than LPI cows (8.3 v. 4.6 and 5.9 v. 2.9 ± 0.55 kg DM/cow per day, respectively, P < 0.01) although PAT, HM and HA were similar between groups. Both groups offered high supplementation levels during these seasons, even though greater in LPI than HPI (14.7 v. 9.7 ± 0.7 kg DM supplement/cow per day, respectively, P < 0.01). On the other hand, differences between groups for both pasture and supplement DMI were more contrasting during spring and summer (13.1 v. 7.3 ± 0.5 and 4.0 v. 11.4 ± 0.4 kg DM/cow per day for HPI and LPI, respectively, P < 0.01), with higher PAT in both seasons (P < 0.05) and higher HA during summer in HPI than LPI (P < 0.01). Unlike LPI, during these seasons HPI adjusted offered supplement according to HA, achieving a higher pasture eDMI and making more efficient use of available pastoral resource than LPI. As there was no grazing limiting condition for pasture harvesting in either group, the main factor affecting pasture DMI was a pasture by supplement substitution effect. These results reinforce the importance of an efficient grazing management, and using supplements to nutritionally complement pasture intake rather than as a direct way to increase milk production.

PSIV-3 Effect of winter-feeding system and roughage level in feedlot ration on subsequent spring grazing behavior and dry matter intake of beef growing heifers

Abstract This study aimed to evaluate the effect of winter-feeding system (grazing, GFS vs. feedlot, FFS) and ration roughage level (RL), on subsequent spring grazing behavior and forage dry matter intake (DMI). Thirty-two Hereford female calves (149 ± 13 kg) were assigned to four winter dietary treatments (110 days) in a randomized block design (n = 2/treatment): three feedlot rations differing RL (Setaria italica) (0%, 35% or 70% DM) or oats grazing (5 kg DM/100 kg LW). In spring (84 days) all treatments grazed a mixed grass-legume pastures (4317 ± 1009 kg DM/ha; 6 kg DM/100 kg LW). During weeks 1, 3 and 5 after changing diets, diurnal behavior activity (effective/search grazing, rumination, idling or water intake) was visually recorded and DMI estimated from the in vivo DM digestibility (DMD) and fecal production. Data were analyzed according to a block design with repeated measures, with general model including block, treatment (T), week (W) and T×W effects. Means were compared through orthogonal contrasts (Table 1). Spring DMI varied with T (P = 0.0084) regardless of W effect (P = 0.1619), with higher values for GFS compared to FFS (1.55 vs. 1.16 kg/100 kg LW, P = 0.0034) and for 70RL compared to 35RL (P = 0.0286). DMD did not differ between treatments (P = 0.2488) but was lower on W1 than W5 (55 vs. 64 %, P = 0.0150). T×W was significant (P &amp;lt; 0.0001) for effective grazing, rumination and idling. On W1, heifers from GFS grazed less (0.40 vs. 0.49, P = 0.0268) but tended to ruminate more (0.26 vs. 0.18, P = 0.0591) than FFS. As pasture DMD improved (W5) GFS grazed more (0.64 vs. 0.51, P = 0.0020) but ruminated less (0.14 vs. 0.21, P = 0.0450) than FFS. Transition from FFS to spring grazing might reduce pasture DMI modifying animal ingestive behavior compare to animals from GFS. Impact could be higher when ration RL is below 70%.

Effect of dietary nitrate on enteric methane emissions, production performance and rumen fermentation of dairy cows grazing ryegrass pasture during spring

Limited studies investigated the effect of dietary nitrate addition as methane (CH4) mitigation strategy for dairy cows grazing pasture. This study aimed to investigate the effect of dietary nitrate addition on daily enteric CH4 emissions, production performance and rumen fermentation of multiparous Jersey cows grazing perennial ryegrass pasture (containing approximately 7.3 g of nitrate/kg of dry matter (DM)). Thirty-two intact and eight rumen-cannulated multiparous Jersey cows were subjected to a replicated 2 × 2 Latin square design with 16 intact cow replicates and four rumen-cannulated cow replicates supplemented with one of two concentrates containing either urea (urea treatment), or urea and nitrate (nitrate treatment) as nonprotein nitrogen source (NPN; containing 0.3 and 15.2 g of nitrate/kg of DM, respectively). Concentrates were formulated to be isonitrogenous and isoenergetic, and was fed at 5.4 kg of DM/cow per d along with a strict daily herbage allowance of 14 kg of DM/cow. Cows were gradually adapted to concentrates over a 3-wk period. Total nitrate intake was 5.2 and 9.7 g of nitrate/kg of DM for the urea and nitrate treatment groups, respectively. Daily enteric CH4 emissions of 28 cows were measured with the sulphur hexafluoride tracer gas technique for six consecutive days during each experimental period with parallel total DM intake (DMI) estimates. Pasture DMI was calculated from faecal output and pasture digestibility using TiO2 and indigestible neutral detergent, respectively. Total DMI (18.1 and 17.8 kg/d), milk yield (19.0 and 18.9 kg/cow per d) and daily CH4 emissions (400 and 405 g/d) were unaffected by dietary treatment for the urea and nitrate group, respectively. Total milk solids content (135 vs. 133 g/kg), milk lactose content (47.3 vs. 46.7 g/kg) and milk urea nitrogen concentration (MUN; 12.6 vs. 11.6 mg/dL) were higher for the nitrate group. Rumen fermentation parameters such as volatile fatty acid profile, ammonium nitrogen, and DM and fibre disappearance were unaffected by treatment. Minor effects on ruminal pH were observed with an increasing tendency towards the nitrate group. In this study, dietary nitrate supplementation was not an effective CH4 mitigation strategy for dairy cows grazing perennial ryegrass. This can be ascribed to the unforeseen high nitrate content of the grazed pasture causing a relative small margin in total nitrate intake between the urea and nitrate treatment diets.

The effect of by-product inclusion and concentrate feeding rate on milk production and composition, pasture dry matter intake, and nitrogen excretion of mid-late lactation spring-calving cows grazing a perennial ryegrass-based pasture

Interest is growing in the use of by-products as economical sources of nutrients that complement grazed grass, particularly at times when grass supply is insufficient to meet the nutritional demands of lactating dairy cattle. The objective of this research was to assess the effect of the amount of by-product inclusion and concentrate feeding rate on pasture dry matter intake, milk production and composition, and N excretion from spring-calving cows grazing summer pasture during mid-late lactation. Forty-eight Holstein Friesian dairy cows were randomly assigned to 1 of 4 dietary treatments in a 2 × 2 factorial design. Cows were grazed in one group on a perennial ryegrass-based sward, with pelleted concentrates offered twice daily during milking over a 63-d experimental period. The dietary treatments were 3 kg of concentrate containing 35% by-products; 6 kg of concentrate containing 35% by-products; 3 kg of concentrate containing 95% by-products; and 6 kg of concentrate containing 95% by-products on a fresh matter basis. The by-products used were soybean hulls, palm kernel expeller, and maize dried distillers grains with solubles, included in equal proportions on a dry matter basis. Pasture dry matter intake (14.5 kg/d) was not affected by the amount of by-product inclusion or feeding rate. By-product inclusion had no effect on milk yield (27.1 kg/d) or milk solids (MS) yield (2.0 kg/d). Cows offered 6 kg of concentrate had a greater milk (+1.6 kg/d) and MS (+0.13 kg/d) yield, consumed more N (+0.08 kg/d), and excreted a lower proportion of N in the milk (0.25 vs. 0.27) and feces (0.39 vs. 0.41) and a higher proportion in the urine (0.39 vs. 0.32) compared with cows offered 3 kg of by-product-based concentrate. In conclusion, by-products can be included at up to 95% of the concentrate fed to cows grazing pasture without affecting pasture dry matter intake, milk production or composition, or N excretion. Cows offered 6 kg of concentrates produced more milk and MS than cows offered 3 kg but had higher urinary N excretion. Economics of this yield response will depend on milk and concentrate prices.

Fatty acid composition of milk from Holstein x Gyr cows grazing on marandu grass supplemented with concentrate containing sunflower oil

The inclusion of plant oils in the diets of grazing cows represents a promising nutritional strategy for the production of milk naturally enriched with bioactive compounds, such as rumenic (cis-9, trans-11 CLA), vaccenic (trans-11 C18:1) and oleic (cis-9 C18:1) acids. The aim of this study was to evaluate the effect of dietary supplementation with sunflower oil (SO) on the fatty acid (FA) composition of milk from Holstein x Gyr dairy cows grazing on Urochloa brizantha cv. Marandu under rotational stocking. Sixteen multiparous cows with 185±10 days in milk received a concentrate containing 0% (control) or 15% SO on a dry matter basis in a randomized block design with two replications (paddocks). The results were analyzed with mixed models (P ? 0.05) using repeated measurements over time, as represented by sampling days 14, 35 and 62 (periods 1, 2 and 3, respectively). In any period, an effect of SO supplementation was observed on milk production, pasture dry matter intake and nutrients intake, whereas the concentrations of most milk FA were altered in SO-fed cows. In particular, dietary supplementation with SO resulted in the production of milk enriched with FA beneficial to human health (rumenic, vaccenic and oleic acids) and with lower levels of hypercholesterolemic lauric (C12:0), myristic (C14:0) and palmitic (C16:0) acids. This positive effect on the nutritional quality of milk fat was more noticeable from the 40th to 43rd days of sunflower oil supplementation.