A. B. D. Pereira

Short communication: Use of a portable, automated, open-circuit gas quantification system and the sulfur hexafluoride tracer technique for measuring enteric methane emissions in Holstein cows fed ad libitum or restricted

The objective of this study was to measure enteric CH4 emissions using a new portable automated open-circuit gas quantification system (GQS) and the sulfur hexafluoride tracer technique (SF6) in midlactation Holstein cows housed in a tiestall barn. Sixteen cows averaging 176 ± 34 d in milk, 40.7 ± 6.1 kg of milk yield, and 685 ± 49 kg of body weight were randomly assigned to 1 out of 2 treatments according to a crossover design. Treatments were (1) ad libitum (adjusted daily to yield 10% orts) and (2) restricted feed intake [set to restrict feed by 10% of baseline dry matter intake (DMI)]. Each experimental period lasted 22d, with 14 d for treatment adaptation and 8d for data and sample collection. A common diet was fed to the cows as a total mixed ration and contained 40.4% corn silage, 11.2% grass-legume haylage, and 48.4% concentrate on a dry matter basis. Spot 5-min measurements using the GQS were taken twice daily with a 12-h interval between sampling and sampling times advanced 2h daily to account for diurnal variation in CH4 emissions. Canisters for the SF6 method were sampled twice daily before milking with 4 local background gas canisters inside the barn analyzed for background gas concentrations. Enteric CH4 emissions were not affected by treatments and averaged 472 and 458 g/d (standard error of the mean = 18 g/d) for ad libitum and restricted intake treatments, respectively (data not shown). The GQS appears to be a reliable method because of the relatively low coefficients of variation (ranging from 14.1 to 22.4%) for CH4 emissions and a moderate relationship (coefficient of determination = 0.42) between CH4 emissions and DMI. The SF6 resulted in large coefficients of variation (ranging from 16.0 to 111%) for CH4 emissions and a poor relationship (coefficient of determination = 0.17) between CH4 emissions and DMI, likely because of limited barn ventilation and high background gas concentration. Research with improved barn ventilation systems or outdoors is warranted to further assess the GQS and SF6 methodologies.

Interactions of corn meal or molasses with a soybean-sunflower meal mix or flaxseed meal on production, milk fatty acid composition, and nutrient utilization in dairy cows fed grass hay-based diets1

We investigated the interactions of corn meal or molasses [nonstructural carbohydrate (NSC) supplements] with a soybean-sunflower meal mix or flaxseed meal [rumen-degradable protein (RDP) supplements] on animal production, milk fatty acids profile, and nutrient utilization in dairy cows fed grass hay diets. Eight multiparous and 8 primiparous Jersey cows averaging 135±49d in milk and 386±61kg of body weight in the beginning of the study were randomly assigned to 4 replicated 4×4 Latin squares with a 2×2 factorial arrangement of treatments. Each period lasted 19d with 14d for diet adaptation and 5d for data and sample collection. Cows were fed diets composed of mixed-mostly grass hay plus 1 of the following 4 concentrate blends: (1) corn meal plus a protein mix containing soybean meal and sunflower meal; (2) corn meal plus flaxseed meal; (3) liquid molasses plus a protein mix containing soybean meal and sunflower meal; or (4) liquid molasses plus flaxseed meal. Data were analyzed for main effects of NSC and RDP supplements, and the NSC × RDP supplement interactions. Significant NSC × RDP supplement interactions were observed for milk urea N, milk N efficiency, and the sums of milk saturated, monounsaturated, and polyunsaturated fatty acids. No effect of NSC supplements was observed for nutrient intake and milk yield. However, 4% fat-corrected milk (-0.70kg/d) and energy-corrected milk (-0.60kg/d) were significantly reduced in cows fed liquid molasses due to a trend to decreased concentration of milk fat (-0.17%). Diets with liquid molasses resulted in increased (+35%) concentration and yield of milk enterolactone, indicating that this mammalian lignan can be modulated by supplements with different NSC profiles. Overall, NSC and RDP supplements profoundly changed the milk fatty acid profile, likely because of differences in fatty acids intake, Δ(9)-desaturase indices, and ruminal biohydrogenation pathways. Feeding liquid molasses significantly reduced plasma urea N (-1.2mg/dL), urinary N excretion (-20g/d), and N digestibility (-3.2 percentage units). Flaxseed meal significantly reduced yields of milk (-1.3kg/d), milk fat (-90g/d), and milk lactose (-60g/d), but significantly increased the concentration and yield of milk enterolactone. Further research is needed to elucidate the negative responses of flaxseed meal on yields of milk and milk components.

Incremental amounts of ground flaxseed decrease milk yield but increase n-3 fatty acids and conjugated linoleic acids in dairy cows fed high-forage diets1

The objective of this study was to investigate the effect of incremental amounts of ground flaxseed (GFX) on milk yield and concentrations and yields of milk components, milk fatty acids (FA) profile, ruminal metabolism, and nutrient digestibility in dairy cows fed high-forage diets. Twelve multiparous Jersey cows averaging (mean ± SD) 112±68d in milk and 441±21kg of body weight and 8 primiparous Jersey cows averaging 98±43d in milk and 401±43kg of body weight were randomly assigned to treatment sequences in a replicated 4×4 Latin square design. Each period lasted 21d with 14d for diet adaptation and 7d for data and sample collection. Treatments were fed as a total mixed ration (63:37 forage-to-concentrate ratio) with corn meal and soybean meal replaced by incremental levels (i.e., 0, 5, 10, or 15% diet dry matter) of GFX. The ruminal molar proportions of acetate and butyrate decreased linearly with GFX supplementation, whereas the ruminal molar proportion of propionate increased linearly resulting in decreased acetate-to-propionate ratio. Apparent total-tract digestibilities of nutrients either decreased (dry matter) or tended to decrease (organic matter, neutral detergent fiber, acid detergent fiber) linearly in cows fed GFX. Milk yield decreased linearly in cows fed increasing amounts of GFX, which is explained by the linear reduction in dry matter intake. Except for the concentrations of milk protein and urea N, which decreased linearly with GFX supplementation, no other changes in the concentration of milk components were observed. However, yields of milk protein and fat decreased linearly with GFX supplementation. The linear decrease in the yields of milk fat and protein are explained by reduced milk yield, whereas that in milk urea N is explained by decreased crude protein intake. No treatment effects were observed for plasma urea N and nonesterified fatty acids, serum cortisol, and body weight change. Milk odd- and branched-chain FA and saturated FA decreased linearly with GFX supplementation. Milk trans-11 18:1, α-linolenic acid, cis-9,trans-11 18:2, and the sum of n-3 FA all increased linearly and quadratically, whereas the milk ratio of n-6 to n-3 decreased linearly in cows fed GFX. Overall, compared with the control diet (0% GFX), the diet with 15% GFX supplementation resulted in the lowest milk yield but highest milk proportions and yields (data not shown) of cis-9,trans-11 18:2 and n-3 FA.

Assessing the research and education needs of the organic dairy industry in the northeastern United States

Demographic and management data about organic dairies have been reported previously, but the current study is the first needs assessment of research and educational priorities of organic dairy farmers in the northeastern United States based directly upon their input. Our objectives were to (1) develop an initial understanding of the emerging research and educational needs of organic dairy farmers in the northeastern United States via focus group interviews, and (2) prioritize the needs identified by the focus groups with a broader population of organic dairy farmers via survey methods. Focus group interviews determined the questions used for the survey questionnaire distributed to 1,200 members of the Northeast Organic Dairy Producers Alliance. The members were asked about demographic information, but more importantly, challenges concerning business management and marketing, organic certification, and animal nutrition, health, and reproduction. The results (183 respondents, 15% response rate) were parsed by region (New England farms compared with New York and Pennsylvania farms), herd size (i.e., 12 to 37, 38 to 59, and >60 cows), and years of organic certification (<4 yr vs. ≥ 4 yr); however, no differences between regions were observed for demographic data. The average farm consisted of 309 acres and 57 milking cows, on which most of the forage was homegrown but grains were purchased (73% of farms). Among the greatest challenges identified by the farmers were obtaining a steady, fair price for milk (85% respondents); determining dry matter intake for animals on pasture (76%); and controlling nuisance flies (89%). Needs for additional research included organic treatments for mastitis (92% respondents), growing forages for organic production (84%), and developing value-added products (84%). Farms with <4 yr of organic certification were concerned with level of knowledge and experience of local certifiers, whereas organic producers with ≥ 4 yr of organic certification were more interested in field testing of new organic products. Opportunities for educational programs included learning about direct marketing possibilities (76% respondents) and providing training to regional veterinarians interested in organic remedies (91%). In conclusion, the information obtained from the current needs assessment provides a foundation for future research proposals and educational outreach programs, germane to stakeholder needs, which could benefit the organic dairy industry within the region and beyond.

Prepartum supplementation of nicotinic acid: Effects on health of the dam, colostrum quality, and acquisition of immunity in the calf

Nicotinic acid (NA) has been shown to reduce lipolysis, alter milk components and the ruminal environment, and increase blood flow. Increased blood flow to the mammary gland during colostrogenesis might increase nutrients and immunoglobulin concentration of colostrum. Twenty-six multiparous Holstein cows were housed in a tiestall barn. Cows were blocked by expected calving date and randomly assigned to 1 of 2 treatments 4 wk prepartum: (1) 0g/d of NA (control, CON) or (2) 48g/d of NA (NA). Total mixed ration amounts fed and refused were measured daily to determine dry matter intake. Blood samples were collected from dams every Monday, Wednesday, and Friday from the coccygeal vein or artery and were analyzed for glucose, nonesterified fatty acids (NEFA), and β-hydroxybutyrate (BHB). Colostrum was collected and weighed within 90 min of parturition. Colostral immunoglobulin G (IgG) concentration was analyzed using radial immunodiffusion assay. Calves were removed from their dams before suckling and weighed within 30 min after birth. Calves received 3 L of a lacteal-based colostrum replacer that provided a total of 225.8g of IgG within 2h of birth. Calf blood samples were collected via jugular venipuncture at 0 and 24h of age and analyzed for IgG concentration and determination of apparent efficiency of absorption. Colostrum yield, dry matter intake, IgG yield, and fat and solids percentage of colostrum did not differ between treatments. Serum concentrations of glucose and BHB were not affected by treatment. We detected an effect of week on serum glucose concentrations at calving and on serum BHB concentrations at 1 wk postpartum. There was a treatment by week effect for serum NEFA concentrations at 1 wk postpartum, where cows that received NA prepartum had higher serum NEFA concentration than CON cows, indicating that a NEFA rebound occurred. No differences were observed for calf body weight, 0- or 24-h serum IgG concentration, or apparent efficiency of absorption. Supplementation of NA increased IgG concentration in colostrum from 73.8 to 86.8g/L. Results indicate that 48g/d of supplemental NA during the prepartum period improved colostrum quality.

Integrating spot short-term measurements of carbon emissions and backward dietary energy partition calculations to estimate intake in lactating dairy cows fed ad libitum or restricted

The objective of this study was to use spot short-term measurements of CH4 (QCH4) and CO2 (QCO2) integrated with backward dietary energy partition calculations to estimate dry matter intake (DMI) in lactating dairy cows. Twelve multiparous cows averaging 173±37d in milk and 4 primiparous cows averaging 179±27d in milk were blocked by days in milk, parity, and DMI (as a percentage of body weight) and, within each block, randomly assigned to 1 of 2 treatments: ad libitum intake (AL) or restricted intake (RI=90% DMI) according to a crossover design. Each experimental period lasted 22d with 14d for treatments adaptation and 8d for data and sample collection. Diets contained (dry matter basis): 40% corn silage, 12% grass-legume haylage, and 48% concentrate. Spot short-term gas measurements were taken in 5-min sampling periods from 15 cows (1 cow refused sampling) using a portable, automated, open-circuit gas quantification system (GreenFeed, C-Lock Inc., Rapid City, SD) with intervals of 12h between the 2daily samples. Sampling points were advanced 2h from a day to the next to yield 16 gas samples per cow over 8d to account for diurnal variation in QCH4 and QCO2. The following equations were used sequentially to estimate DMI: (1) heat production (MJ/d)=(4.96 + 16.07 ÷ respiratory quotient) × QCO2; respiratory quotient=0.95; (2) metabolizable energy intake (MJ/d)=(heat production + milk energy) ± tissue energy balance; (3) digestible energy (DE) intake (MJ/d)=metabolizable energy + CH4 energy + urinary energy; (4) gross energy (GE) intake (MJ/d)=DE + [(DE ÷ in vitro true dry matter digestibility) - DE]; and (5) DMI (kg/d)=GE intake estimated ÷ diet GE concentration. Data were analyzed using the MIXED procedure of SAS (SAS Institute Inc., Cary, NC) and Fit Model procedure in JMP (α=0.05; SAS Institute Inc.). Cows significantly differed in DMI measured (23.8 vs. 22.4kg/d for AL and RI, respectively). Dry matter intake estimated using QCH4 and QCO2 coupled with dietary backward energy partition calculations (Equations 1 to 5 above) was highest in cows fed for AL (22.5 vs. 20.2kg/d). The resulting R(2) were 0.28 between DMI measured and DMI estimated by gaseous measurements, and 0.36 between DMI measured and DMI predicted by the National Research Council model (2001). Results showed that spot short-term measurements of QCH4 and QCO2 coupled with dietary backward estimations of energy partition underestimated DMI by 7.8%. However, the approach proposed herein was able to significantly discriminate differences in DMI between cows fed for AL or RI.

Production and nitrogen utilization in lactating dairy cows fed ground field peas with or without ruminally protected lysine and methionine

Previous research has shown that cows fed ≥24% of the diet dry matter (DM) as field peas decreased milk yield as well as concentration and yield of milk protein, possibly due to reduced DM intake and limited supply of Lys and Met. Twelve multiparous and 4 primiparous lactating Holstein cows were randomly assigned to 1 of 4 diets in a replicated 4 × 4 Latin square design. The diets contained (DM basis) 34.8% corn silage, 15.2% grass-legume silage, 5.9% roasted soybean, 2.4% mineral-vitamin premix, 2.0% alfalfa pellets, and either (1) 36% ground corn, 2.4% soybean meal, and 1.3% urea (UR), (2) 29.7% ground corn, 9.8% soybean meal, 0.13% ruminally protected (RP) Lys, and 0.07% RP-Met (CSBAA), (3) 25% ground field peas, 12.3% ground corn, and 2.4% soybean meal (FP), or (4) FP supplemented with 0.15% RP-Lys and 0.05% RP-Met (FPAA). Our objective was to test the effects of FP versus UR, FPAA versus CSBAA, and FPAA versus FP on milk yield and composition, N utilization, nutrient digestibility, ruminal fermentation profile, and plasma concentration of AA. Milk yield did not differ across diets. Compared with cows fed UR, those fed FP had greater DM intake, concentration and yield of milk true protein, apparent total-tract digestibility of fiber, urinary excretion of purine derivatives, and concentrations of total volatile fatty acids in the rumen and Lys in plasma, and less milk urea N and ruminal NH3-N. The concentration of milk urea N, as well as the concentration and yield of milk fat increased in cows fed FPAA versus CSBAA. Moreover, cows fed FPAA had greater ruminal concentration of total volatile fatty acids, increased proportions of acetate and isobutyrate, and decreased proportions of propionate and valerate than those fed CSBAA. The plasma concentrations of His, Leu, and Phe decreased, whereas plasma Met increased and plasma Lys tended to increase in cows fed FPAA versus CSBAA. Concentration of milk true protein, but not yield, was increased in cows fed FPAA versus FP. However, cows fed FPAA showed decreased concentrations of His and Leu in plasma compared with those fed FP. Overall, compared with the CSBAA diet, feeding FPAA did not negatively affect milk yield and milk protein synthesis. Furthermore, RP-Lys and RP-Met supplementation of the FP diet did not improve milk yield or milk protein synthesis, but decreased urinary urea N excretion.