Grazing Dairy Farms Research Articles

A cost-effective management practice to decrease phosphorus loss from dairy farms.

Phosphorus (P) loss from land can impair surface water quality. A paired-catchment study was conducted on a grazed dairy farm that tested the hypothesis that cultivating and sowing a low-P-requiring grass in near stream areas and high-P-requiring clover ( L.) elsewhere lost less P to water and was potentially more profitable than a mixed grass-clover pasture managed for the cover component. Two catchments were treated the same for 2 yr, after which 40% of the treatment catchment was cultivated around the stream, sown in ryegrass ( L.) and fertilized with 150 kg nitrogen (N) ha yr and 10 kg P ha yr. White clover was established in the remainder of the catchment and received no N but 30 kg P ha yr. The control catchment received 150 kg N ha yr and 30 kg P ha yr. After the monocultures were installed, filterable reactive P and total P concentrations decreased by 44 and 26% respectively, while the better-quality forage suggested a possible improvement in profitability. We concluded that with some caveats (e.g., a 2% increase in modeled N loss), using grass-clover monocultures strategically across a dairy farm may decrease P loss to surface water and improve profitability compared with a mixed pasture.

Epidemiological analysis of an outbreak of foot-and-mouth disease (serotype SAT2) on a large dairy farm in Kenya using regular vaccination

During August–September 2012, an outbreak of Foot-and-mouth Disease (FMD) due to serotype Southern African Territories-2 (SAT2) occurred on a large, extensively grazed dairy farm in Nakuru County, Kenya. Over 29 days, 400/644 (62.1%) cattle were recorded as displaying clinical signs consistent with FMD. Out of the 18 management groups present, 17 had clinical cases (weighted mean incidence rate 3.5 per 100 cattle-days, 95% CI 2.4, 5.1; range 0.064–10.9). Transmission may have been encouraged when an infected group was moved to a designated isolation paddock. A four to five day minimum incubation period was apparent in five groups for which a point source exposure was evident. Further transmission was associated with the movement of individual animals incubating infection, use of a common dip and milking parlour, and grazing of susceptible groups in paddocks neighbouring to infectious cases. Animals over 18 months old appeared to be at highest risk of disease possibly due to milder clinical signs seen among younger animals resulting in reduced transmission or cases not being recorded. Cows with a breeding pedigree containing a greater proportion of zebu appeared to be at lower risk of disease. The outbreak occurred despite regular vaccination (three times per year) last performed approximately three months before the index case. Incidence risk by the lifetime number of doses received indicated limited or no vaccine effectiveness against clinical disease. Reasons for poor vaccine effectiveness are discussed with antigenic diversity of the SAT2 serotype and poor match between the field and vaccine strain as a likely explanation. Detailed field-derived epidemiological data based on individual animals are rarely presented in the literature for FMD, particularly in East-Africa and with the SAT2 serotype. This study provides a detailed account and therefore provides a greater understanding of FMD outbreaks in this setting. Additionally, this is the first study to provide field-derived evidence of poor vaccine effectiveness using a SAT2 vaccine. Further field-based measures of vaccine effectiveness in line with evaluation of human vaccines are needed to inform FMD control policy which has previously relied heavily upon experimental data and anecdotal experience.

Practices to Reduce Milk Carbon Footprint on Grazing Dairy Farms in Southern Uruguay: Case Studies

<p>Carbon footprint (CF) is an increasingly important indicator of the impact of a product on climate change. This study followed international guidelines to quantify the CF of milk produced on 24 grazing-based dairy farms in southern Uruguay. Cows grazed all year-round and were supplemented with concentrate feeds. Dairy farms varied in annual milk yield per cow (5672 ± 1245 kg fat and protein corrected milk [FPCM]), milk production per ha (4075 ± 1360 kg FPCM/ha), cow stocking rate (0.71 ± 0.12 cows/ha), feed intake (13.3 ± 2.2 kg dry matter [DM]/cow/day) and percentage of concentrate in the diet (36 ± 12% DM) giving an average CF of 0.99 ± 0.10 kg CO<sub>2</sub> (equivalent [eq]/kg FPCM) over all farms. Total milk production per ha, milk yield per cow and dry matter intake explained most of the variation in CF. Strategies that provide the highest milk production per ha using high yielding cows and a high portion of lactating cows in the herd were identified as the best management practices for reducing CF. Low forage intake in Uruguay is often a consequence of low yielding pastures and high stocking rates. Overall, this study concluded that a reduction in CF is not achieved through increased concentrate intake unless forage consumption is also unconstrained. Improved pasture and feeding management can be used to reduce the CF of milk produced in Uruguay.</p>

Reproduction in grazing dairy cows treated with 14-day controlled internal drug release for presynchronization before timed artificial insemination compared with artificial insemination after observed estrus

Progesterone-releasing (controlled internal drug release, CIDR) devices inserted for 14d are used to presynchronize the estrous cycle for timed artificial insemination (TAI) in beef heifers (14-d CIDR-PGF2α program). The objective was to test a similar program in dairy cows by measuring first-service conception rates (FSCR), pregnancy rates after 2 AI, and time to pregnancy compared with a control (AI after observed estrus). Postpartum cows (Holstein, Jersey, or crossbred; n=1,363) from 4 grazing dairy farms were assigned to 1 of 2 programs: 14dCIDR_TAI [CIDR in for 14d, CIDR out, PGF2α injection at 19d after CIDR removal, GnRH injection 56h later, and then TAI 16h later; n=737] or control [AI after observed estrus; reproductive program with PGF2α (cycling cows) and CIDR (noncycling cows) to synchronize estrus with the start of the breeding season; n=626]. Body condition was scored (1 to 5; thin to fat) at the start of the trial. The interval from the start of the breeding period (final PGF2α injection of either program) to first AI was shorter for 14dCIDR_TAI compared with the control (3.0±0.2 vs. 5.3±0.2d; mean ± SEM) but 14dCIDR_TAI cows had lesser FSCR than controls (48 vs. 61%). Farm affected FSCR (50, 51, 67, and 58% for farms 1 to 4). The BCS affected FSCR (50, 55, and 62% for BCS=2, 2.5, and 3, respectively). Cows that either calved the year before (carryover) or that calved early in the calving season had greater FSCR than cows that calved later in the calving season (55, 61, and 42%, respectively). The percentage of cows pregnant to AI (first and second inseminations within 31-d breeding season) was similar for 14dCIDR_TAI and control (64 vs. 70%) cows, but farm (64, 62, 80, and 69%) and time of calving (70, 76, and 56%: carryover, early, and late, respectively) affected the percentage. Survival analyses showed an initial advantage for 14dCIDR_TAI (more cows inseminated and more pregnancies achieved early in the breeding season) that was not maintained over time. Conclusions were that the 14dCIDR_TAI program achieved acceptable FSCR (48%) and overall AI pregnancy rates (64%), but did not surpass a control program that used AI after observed estrus (61 and 70%, respectively).

Fertility in dairy cows following presynchronization and administering twice the luteolytic dose of prostaglandin F2α as one or two injections in the 5-day timed artificial insemination protocol

The objectives were to evaluate pregnancy per AI (P/AI) of dairy cows subjected to the 5-day timed AI protocol under various synchronization and luteolytic treatments. Cows were either presynchronized or received supplemental progesterone during the synchronization protocol, and received a double luteolytic dose of PGF2α, either as one or two injections. In Experiment 1, dairy cows (n = 737; Holstein = 250, Jersey = 80, and crossbred = 407) in two seasonal grazing dairy farms were randomly assigned to one of four treatments in a 2 × 2 factorial arrangement. The day of AI was considered study Day 0. Half of the cows were presynchronized (G6G: PGF2α on Day −16 and GnRH on Day −14) and received the 5-day timed AI protocol using 1 mg of cloprostenol, either as a single injection (G6G-S: GnRH on Day −8, PGF2α on Day −3, and GnRH + AI on Day 0) or divided into two injections of 0.5 mg each (G6G-T: GnRH on Day −8, PGF2α on Day −3 and −2, and GnRH + AI on Day 0). The remaining cows were not presynchronized and received a controlled internal drug-release (CIDR) insert containing progesterone from GnRH to the first PGF2α injection of the 5-day timed AI protocol, and 1 mg of cloprostenol either as a single injection on Day -3 (CIDR-S) or divided into two injections of 0.5 mg each on Days -3 and -2 (CIDR-T). Ovaries were examined by ultrasonography on Days −8 and −3 and plasma progesterone concentrations were determined on Days −3 and 0. In Experiment 2, 655 high-producing Holstein cows had their estrous cycle presynchronized with PGF2α at 46 ± 3 and 60 ± 3 days postpartum and were randomly assigned to receive 50 mg of dinoprost during the 5-day timed AI protocol, either as a single injection or divided into two injections of 25 mg each. Pregnancies per AI were determined on Days 35 and 64 after AI in both experiments. In Experiment 1, presynchronization with G6G increased the proportion of cows with a CL on Day −8 (80.6 vs. 58.8%), ovulation to the first GnRH of the protocol (64.2 vs. 50.2%), and the presence (95.6 vs. 88.4%) and number (1.79 vs. 1.30) of CL at PGF2α compared with CIDR cows. Luteolysis was greater for two injections compared to a single PGF2α injection (two PGF2α = 95.9 vs. single PGF2α = 72.2%), especially in presynchronized cows (G6G-T = 96.2 vs. G6G-S = 61.7%). For cows not presynchronized, two PGF2α injections had no effect on P/AI (CIDR-S = 30.2 vs. CIDR-T = 34.3%), whereas for presynchronized cows, it improved P/AI (G6G-S = 28.7 vs. G6G-T = 45.4%). In Experiment 2, the two-PGF2α injection increased P/AI on Days 35 (two PGF2α = 44.5 vs. single PGF2α = 36.4%) and 64 (two PGF2α = 40.3% vs. single PGF2α = 32.6%) after AI. Presynchronization and dividing the dose of PGF2α (either cloprostenol or dinoprost) into two injections increased P/AI in lactating dairy cows subjected to the 5-day timed AI protocol.

Environmental and Economic Comparisons of Manure Application Methods in Farming Systems

Alternative methods for applying livestock manure to no-till soils involve environmental and economic trade-offs. A process-level farm simulation model (Integrated Farm System Model) was used to evaluate methods for applying liquid dairy (Bos taurus L.) and swine (Sus scrofa L.) manure, including no application, broadcast spreading with and without incorporation by tillage, band application with soil aeration, and shallow disk injection. The model predicted ammonia emissions, nitrate leaching, and phosphorus (P) runoff losses similar to those measured over 4 yr of field trials. Each application method was simulated over 25 yr of weather on three Pennsylvania farms. On a swine and cow-calf beef operation under grass production, shallow disk injection increased profit by $340 yr(-1) while reducing ammonia nitrogen and soluble P losses by 48 and 70%, respectively. On a corn (Zea mays L.)-and-grass-based grazing dairy farm, shallow disk injection reduced ammonia loss by 21% and soluble P loss by 76% with little impact on farm profit. Incorporation by tillage and band application with aeration provided less environmental benefit with a net decrease in farm profit. On a large corn-and-alfalfa (Medicago sativa L.)-based dairy farm where manure nutrients were available in excess of crop needs, incorporation methods were not economically beneficial, but they provided environmental benefits with relatively low annual net costs ($13 to $18 cow). In all farming systems, shallow disk injection provided the greatest environmental benefit at the least cost or greatest profit for the producer. With these results, producers are better informed when selecting manure application equipment.

Estimating Forage Mass with a Commercial Capacitance Meter, Rising Plate Meter, and Pasture Ruler

Accurate assessment of forage mass in pastures is key to budgeting forage in grazing systems. Our objective was to determine the accuracy of an electronic capacitance meter, a rising plate meter, and a pasture ruler in measuring forage mass and to determine the cost of measurement inaccuracy. Forage mass was estimated in grazed pastures on farms in Pennsylvania, Maryland, and West Virginia in 1998 and 1999. Forage mass estimated by each method was compared with forage mass estimated by hand‐clipped samples. None of these indirect methods were accurate or precise, and error levels ranged from 26 to 33% of the mean forage mass measured on the pastures. The computer model DAFOSYM (Dairy Forage System Model) was used to simulate farm performance and the resulting effects of inaccuracies in estimating forage mass on pasture. A representative grazing dairy farm was developed, and the costs and returns from low‐input and conventional managements were calculated. Different scenarios were then simulated, including under‐ or overestimating forage yield on pastures by 10 or 20%. All scenarios simulated resulted in lower returns compared with the optimum farm, with decreases in net return ranging from $8 to $198 ha−1 yr−1. Underestimating forage mass resulted in less hay and silage being harvested, more pasture being consumed, and more forage purchased compared with the optimum scenario. The opposite occurred for overestimation of forage mass. Our results indicate that achieving greater accuracy (to within 10% of actual pasture yield) in estimating pasture yields will improve forage budgeting and increase net returns.

Economic and Environmental Impact of Four Levels of Concentrate Supplementation in Grazing Dairy Herds

Low-cost, pasture-based forage systems are a viable management alternative for small to moderately sized dairy farms in the Northeast United States. A whole farm analysis was conducted to evaluate the potential long-term environmental impact and economic benefit of varying the level of concentrate supplementation on seasonal grazing dairies. A representative dairy farm was simulated with various production strategies over 25 yr of historical Pennsylvania weather using the Dairy Forage System Model. A representative grazing farm (81ha) was simulated with four levels of daily concentrate supplementation: 1) no supplement, 2) 3kg of DM/cow in early lactation, 3) 6kg of DM/cow in early lactation, and 4) 9kg of DM/cow in early lactation fed daily to the lactating cows to meet annual milk production levels of 5000, 6068, 6968, and 7700 kg/cow, respectively. These farm systems were then compared to an alfalfa- and corn-based confinement system on the same land base where total mixed rations were fed to maintain an annual milk production level of 9000 kg/cow. The five systems were simulated for three scenarios. In the first, total milk sold per farm (625,000kg) was similar across all systems. In the second, cow numbers were held constant across all systems (100 mature cows), and total milk sold per farm varied. In the third, stocking rate was set so that forage consumed equaled forage production on the farm. Profitability increased as supplementation level increased in the grazing systems, but at a decreasing rate with each successive level of supplementation. At higher levels of supplementation, the grazing dairy farms showed greater profitability than the confinement systems. Economic risk or year-to-year variation also decreased as concentrate supplementation level increased. The grazing systems showed an environmental benefit compared with the confinement systems by decreasing nitrogen leaching losses. Concentrate supplementation of grazing lactating dairy cows provided an increase in profitability and a mixed impact on nutrient balance of the farm.

Estimation of potassium losses from a grazed dairy farm in Taranaki

Abstract The potassium (K) lost through animal products (milk, calf and culled stock) and transfer of excretai K to the dairy shed and raceways, was estimated at 1.6 kg/stock unit (SU) for a dairy farmlet of small herd size, assuming the cows spend 5% of the year off the paddock. This loss increased to 2.5 kg K/SU if the cows spend 10% of the year off the paddock as is likely on a dairy farm with a larger number of cows. These values are lower than the 4 kg K/SU currently used by the Ministry of Agriculture and Fisheries as the animal loss factor (ALF) in their fertiliser advice scheme for dairying on flat-rolling country in New Zealand.