A comparison of the environmental impact of Jersey compared with Holstein milk for cheese production.

The objective of this study was to compare the environmental impact of Jersey or Holstein milk production sufficient to yield 500,000 t of cheese (equivalent cheese yield) both with and without recombinant bovine somatotropin use. The deterministic model used 2009 DairyMetrics (Dairy Records Management Systems, Raleigh, NC) population data for milk yield and composition (Jersey: 20.9 kg/d, 4.8% fat, 3.7% protein; Holstein: 29.1 kg/d, 3.8% fat, 3.1% protein), age at first calving, calving interval, and culling rate. Each population contained lactating and dry cows, bulls, and herd replacements for which rations were formulated according to DairyPro (Agricultural Modeling and Training Systems, Cornell, Ithaca, NY) at breed-appropriate body weights (BW), with mature cows weighing 454 kg (Jersey) or 680 kg (Holstein). Resource inputs included feedstuffs, water, land, fertilizers, and fossil fuels. Waste outputs included manure and greenhouse gas emissions. Cheese yield (kg) was calculated according to the Van Slyke equation. A yield of 500,000 t of cheese required 4.94 billion kg of Holstein milk compared with 3.99 billion kg of Jersey milk-a direct consequence of differences in milk nutrient density (fat and protein contents) between the 2 populations. The reduced daily milk yield of Jersey cows increased the population size required to supply sufficient milk for the required cheese yield, but the differential in BW between the Jersey and Holstein breeds reduced the body mass of the Jersey population by 125×10(3) t. Consequently, the population energy requirement was reduced by 7,177×10(6) MJ, water use by 252×10(9) L, and cropland use by 97.5×10(3) ha per 500,000 t of cheese yield. Nitrogen and phosphorus excretion were reduced by 17,234 and 1,492 t, respectively, through the use of Jersey milk to yield 500,000 t of Cheddar cheese. The carbon footprint was reduced by 1,662×10(3) t of CO(2)-equivalents per 500,000 t of cheese in Jersey cows compared with Holsteins. Use of recombinant bovine somatotropin reduced resource use and waste output in supplemented populations, with decreases in carbon footprint equivalent to 10.0% (Jersey) and 7.5% (Holstein) compared with nonsupplemented populations. The interaction between milk nutrient density and BW demonstrated by the Jersey population overcame the reduced daily milk yield, thus reducing resource use and environmental impact. This reduction was achieved through 2 mechanisms: diluting population maintenance overhead through improved milk nutrient density and reducing maintenance overhead through a reduction in productive and nonproductive body mass within the population.

Effect of recombinant bovine somatotropin and a shortened or no dry period on the performance of lactating dairy cows.

The objective of this study was to determine the effects of altering dry period length in multiparous dairy cows (n = 341) on milk production for a full lactation (294 d). The study used 3 commercial herds in the western United States. Cows producing greater than 8,400 kg of mature-equivalent milk were assigned to treatments 60 d before their due dates. The 4 treatments were 1) 60-d dry period, label use of recombinant bovine somatotropin (rbST; 60d-L); 2) 32-d dry period, label use of rbST (32d-L); 3) 0-d dry period, label use of rbST (0d-L); and 4) 0-d dry period, continuous use of rbST (0d-C). Cows with shortened dry periods produced 625, 1,000, and 1,042 kg of milk during the prepartum period for treatments 2 to 4, respectively. During the postpartum period, cows on the 32d-L treatment produced similar amounts of milk compared with the 60d-L treatment (11,490 vs. 11,968 kg, respectively). However, cows on the 0d-L (10,316 kg) and 0d-C (10,195 kg) treatments produced significantly lower amounts of milk during the postpartum period compared with the 60d-L treatment. Total milk production from the prepartum and postpartum periods was not altered significantly and was 11,974, 12,112, 11,310, and 11,230 kg for treatments 1 to 4, respectively. The concentrations of beta-hydroxybutyrate and nonesterified fatty acids in serum after calving were decreased for cows on the 32d-L, 0d-L, and 0d-C treatments compared with cows on the 60d-L treatment, which may indicate improved metabolic status.

The environmental impact of dairy production: 1944 compared with 2007.

A common perception is that pasture-based, low-input dairy systems characteristic of the 1940s were more conducive to environmental stewardship than modern milk production systems. The objective of this study was to compare the environmental impact of modern (2007) US dairy production with historical production practices as exemplified by the US dairy system in 1944. A deterministic model based on the metabolism and nutrient requirements of the dairy herd was used to estimate resource inputs and waste outputs per billion kg of milk. Both the modern and historical production systems were modeled using characteristic management practices, herd population dynamics, and production data from US dairy farms. Modern dairy practices require considerably fewer resources than dairying in 1944 with 21% of animals, 23% of feedstuffs, 35% of the water, and only 10% of the land required to produce the same 1 billion kg of milk. Waste outputs were similarly reduced, with modern dairy systems producing 24% of the manure, 43% of CH(4), and 56% of N(2)O per billion kg of milk compared with equivalent milk from historical dairying. The carbon footprint per billion kilograms of milk produced in 2007 was 37% of equivalent milk production in 1944. To fulfill the increasing requirements of the US population for dairy products, it is essential to adopt management practices and technologies that improve productive efficiency, allowing milk production to be increased while reducing resource use and mitigating environmental impact.

Evaluation of dairy bulls in Ontario for calving ease of offspring.

The first sire evaluations for calving ease for bulls used in Ontario were published in May, 1981. Evaluations used calving records collected by Ontario Dairy Herd Improvement Association from all supervised herds from May, 1980, to April, 1981. A total of 34,240 records including herd, breed, sire, and cow identification, date of calving, and information about cow size, parity, sex of calf, mortality, and dystocia score were collected. After editing, 28,947 records were available from 1,178 Holstein bulls. Dystocia scores were 1) unobserved or unassisted, 2) easy pull, 3) hard pull, and 4) surgery. Stillbirths represented 5.5% of births coded 1 and 2, 25.1% of births coded hard pull, and 50.7% of surgical births. Analysis of variance showed that cow size, sex of calf, parity, and season (May to September and October to April) affected dystocia scores. Variance components were estimated prior to evaluation by Henderson's new method and resulted in a heritability of .08. Sire evaluation was by best linear unbiased prediction and included the relationship matrix. The prediction model included herd-year-season, dam size-parity-sex, and sire effects. Ninety-one sires had evaluations with a Repeatability of at least 55% and records in at least 20 herd-year-seasons.

Factors affecting milk fat percent of Nili-Ravi buffaloes in Pakistan.

Monthly fat tests for 895 lactations of Nili-Ravi buffaloes in a Livestock Production Research Institute herd were used to estimate environmental effects on fat percentage. Fat tests rose progressively from 1st to 10th mo of lactation (5.51 to 7.46%). Average lactation fat percent was 6.55 +/- .06. Year effects were significant, but season, age, parity, milk yield, and health status were not. Percent fat increased slightly to maturity (6.54 first parity; 6.65 fifth). Lactations initiated April to September averaged slightly higher (6.60%) than other months (6.50%). There was a slight, although real, decrease in fat percent with increased lactation milk yield (6.60, 6.63, 6.60, 6.43, 6.51 for 1000 to 1500, 1501 to 2000, 2001 to 2500, 2501 to 3000, and greater than 3,000 kg). Effect of treatment for health problems was small (6.51 treated versus 6.59% untreated). Of all fat tests (7,772) 60% were 5.1 to 7.0%, 27% were between 7 and 9%, but only 3% exceeded 9%. Lactation fat percent averaged 1.0 less than most percents for buffaloes because of system of milking and milk yield (2,130 kg). Fat percentage of buffaloes appears to be influenced by environmental factors in the same proportion as for cattle, but buffaloes would be expected to exceed cattle in fat percent by 1 to 3% depending on breed and environmental conditions.

Factors affecting performance of Nili-Ravi buffaloes in Pakistan.

Effects of herd, year, age, season, and lactation length on milk yield and reproductive efficiency for the Nili-Ravi breed of buffalo were determined by analysis of variance of 5,716 lactation records from two herds in Pakistan. Herds differed in all traits. Herd average milk yields were 1,702 and 2,064 kg. Year, season, herd, parity number, days in milk, days open, age, and sire all influenced milk yield. Herd, year, season, and parity number also had significant effects on days open and calving interval. Month of calving was important for time until return to estrus. Percentages of variance in milk yield attributed to herd, year, sire, cow, and residual were 20.3, 11.4, 4.3, 17.0, and 47.0. Classification of lactation length (greater than 60, greater than 250, or at least 305 days) markedly influenced the sire component of variance suggesting some interdependence of milk yield and lactation length. Total variance for milk yield was 466,911 kg2. Within herd heritability for milk yield was .25, and repeatability was low (.31). Predicted breeding values for sires for 250 to 305-day milk ranged from -172 kg to +260. Cows in Herd 1 completed 5.58 lactations with an average herd life of 12.3 yr; Herd 2 cows completed 4.52 lactations with culling at 10.6 yr. Frequency of termination of lactations because of mastitis, reproductive problems, or health was similar to frequencies for cattle. Factors affecting milk yield in buffaloes are similar to those of cattle.