The effects of cow genetic group on the density of raw whole milk

peer reviewedThe density of milk is dependent upon various factors including temperature, processing conditions, and animal breed. This study evaluated the effect of different cow genetic groups, Jersey, elite Holstein Friesians (EHF), and national average Holstein Friesians (NAHF) on the compositional and physicochemical properties of milk. Approximately 1,040 representative (morning and evening) milk samples (~115 per month during 9 mo) were collected once every 2 wk. Milk composition was determined with a Bentley Dairyspec instrument. Data were analysed with a mixed linear model that included the fixed effects of sampling month, genetic group, interaction between month and genetic group and the random effects of cow to account for repeated measures on the same animal. Milk density was determined using three different analytical approaches – a portable and a standard desktop density meter and 100 cm3 calibrated glass pycnometers. Milk density was analysed with the same mixed model as for milk composition but including the analytical method as a fixed effect. Jersey cows had the greatest mean for fat content (5.69 ± 0.13%), followed by EHF (4.81 ± 0.16%) and NAHF (4.30 ± 0.15%). Milk density was significantly higher (1.0313 g/cm³ ± 0.00026, P < 0.05) for the milk of Jersey breed when compared to the EHF (1.0304 ± 0.00026 g/cm³) and NAHF (1.0303 ± 0.00024 g/cm³) genetic groups. The results from this study can be used by farmers and dairy processors alike to enhance accuracy when calculating the quantity and value of milk solids depending upon the genetic merit of the animal/herd, and may also improve milk payment systems through relating milk solids content and density

Fatty Acid Composition and Thermal Properties of Lipid From Milk and Butter From Lactating Holstein Cows Fed a Supplemental Lipid Either High or Low In Palmitic Acid

Abstract of paper presented at the 2006 Joint Annual Meeting of the American Dairy Science Association & the American Society of Animal Science

The Use of Supplement Blocks for Sheep Grazing Dry, Annual Pastures in California

The objective of this study was to evaluate the use of supplement blocks on body weight change, blood parameters, and lambing performance of ewes grazing dry, annual grasses during the summer prior to and during breeding. Two experiments were conducted in successive years to compare performance of unsupplemented control (C) and supplemented (S) Targhee ewes. In the first season, yearling ewes were used while aged ewes (2 or 4 years) were used during the second season. During the first year (1980), supplemented ewes lost less body weight during the dry grazing season than C ewes. However, no lambing performance difference was found between C and S groups. During the second year (1981), supplemented ewes maintained their body weight over the summer while C ewes lost weight. In addition, lambing performance (multiple births) was higher for S than C ewes. Supplementation of ewes with blocks containing molasses, urea, protein, and minerals required little labor input. However, based on lambing performance, it is unlikely that supplementation would be economically profitable under the range conditions utilized in these trials.This material was digitized as part of a cooperative project between the Society for Range Management and the University of Arizona Libraries.The Journal of Range Management archives are made available by the Society for Range Management and the University of Arizona Libraries. Contact [email protected] for further information.Migrated from OJS platform August 202

Carbon and blue water footprints of California sheep production

While the environmental impacts of livestock production have been studied for a variety of livestock production systems, information is still lacking for US sheep production. A cradle-to-farm gate life cycle assessment was conducted according to international standards (ISO 14040/44), analyzing the impacts of five different meat sheep production systems in California, and focusing on carbon footprint (carbon dioxide equivalents, CO2sub&gt;22e) and irrigated water usage (MT). This study is the first to look at the carbon footprint of the California sheep industry and to consider both wool and meat production across the diverse sheep production systems within California. This study also explicitly examined the carbon foot-print of hair sheep as compared with wooled sheep production. Data were derived from producer interviews and literature values, and California-specific emission factors were used wherever possible. The carbon footprint of market lamb production ranged from 13.9 to 30.6 kg CO2e/kg market lamb production on a mass basis, 10.4 to 18.1 on an economic basis, and 6.59 to 10.1 on a protein mass basis. Whole-ranch water usage ranged from 2.06 to 44.8 MT/kg market lamb, almost entirely from feed production, and four of five case studies used irrigated pasture for at least part of the year. Enteric methane (CH4) production was the largest single source of emissions for all case studies, averaging 72% of total emissions. Emissions from manure credited to feed or from feed production averaged 22% in total. Sensitivity analysis showed that carbon footprint per kg market lamb increased as ewe replacement rate increased and decreased as lambs born/ewe bred increased. These results provide a proactive benchmark for the previously-unknown environmental impacts of current sheep production systems in California, which could be used to spur research into other US sheep production systems

Supplementation with calcium salts of linoleic and trans-octadecenoic acids improves fertility of lactating dairy cows

Objectives were to evaluate effects of feeding a calcium salt rich in linoleic and trans-octadecenoic acids (LTFA) on synthesis of prostaglandin F(2alpha) based on its metabolite (PGFM), uterine involution and pregnancy rates in lactating dairy cows. Five hundred and eleven Holstein cows were blocked according to parity, body condition score and milk yield in the previous lactation. Primiparous and multiparous cows were randomly assigned to one of the two treatments consisting of calcium salt (2% diet dry matter) of either palm oil (PO) or LTFA from 25 days prepartum to 80 days of lactation. Cows were time-inseminated at 70 +/- 3 days postpartum. Feeding LTFA tended (p = 0.08) to decrease the incidence of puerperal metritis (15.1% vs 8.8%). Primiparous cows supplemented with LTFA showed larger increase in plasma PGFM concentration at day 1 postpartum (17018 vs 6897 pm). Pregnancy rate after first insemination tended (p = 0.07) to be greater at 27 days after insemination (37.9% vs 28.6%), and was greater (p = 0.05) at 41 days after insemination (35.5% vs 25.8%) for cows fed LTFA compared with PO. These results indicate that unsaturated fatty acids fed in a rumen inert form have the potential to modulate reproductive events and improve pregnancy rates in lactating dairy cows