The effect of long-chain polyunsaturated fatty acid and vitamin E supplementation of ewes on neonatal lamb behaviour and performance

Three experiments investigated the effect of long-chain polyunsaturated fatty acid (PUFA) and vitamin E supplementation of ewes upon lamb vigour and performance. In Experiment One, four diets were fed to 48 ewes in a two-by-two factorial design. Each diet contained either fish oil (high in C20:5n-3 and C22:6n-3) or Megalac® (control fat, C16:0) and a basal (50 mg/kg) or supranutritional (500 mg/kg) concentration of vitamin E. Fish oil supplementation significantly increased ewe gestation length, deposition of C22:6n-3 in lamb brain tissue and neonatal lamb vigour. It also had significant detrimental effects upon milk composition and lamb growth. Vitamin E supplementation of the ewe increased the concentration of the vitamin in lamb brain and muscle tissue, and improved lamb birthweight. Within Experiment Two, three treatment diets based on algae (high in C22:6n-3), linseed (high in C18:3n-3) or Megalac® were fed to sixty pregnant ewes. After parturition, thirty ewes were changed onto diets containing either linseed or Megalac®. Gestation length and brain C22:6n-3 content were unaffected by diet, although lamb vigour was improved by maternal PUFA supplementation. The use of strategic supplementation abrogated the effects of PUFA supplementation upon lamb growth rate. Nevertheless, significant effects of algal supplementation were observed upon milk composition after a 28-day change-over period. Experiment Three employed three diets, each containing either fish oil or Megalac® plus basal or supranutritional vitamin E, followed by Megalac® supplementation during lactation. Gestation length and lamb behaviour were unaffected by treatment diet. Differences in milk composition were observed 28 days after the diet change. Long-chain PUFA supplementation of the pregnant ewe appears to improve neonatal lamb vigour, although effects upon milk composition cannot be negated by changing the dietary fat source during lactation. The vitamin E status of the neonatal lamb may be manipulated by maternal supplementation

A case study of the carbon footprint of milk from high-performing confinement and grass-based dairy farms

Life-cycle assessment (LCA) is the preferred methodology to assess carbon footprint per unit of milk. The objective of this case study was to apply an LCA method to compare carbon footprints of high-performance confinement and grass-based dairy farms. Physical performance data from research herds were used to quantify carbon footprints of a high-performance Irish grass-based dairy system and a top-performing United Kingdom (UK) confinement dairy system. For the US confinement dairy system, data from the top 5% of herds of a national database were used. Life-cycle assessment was applied using the same dairy farm greenhouse gas (GHG) model for all dairy systems. The model estimated all on- and off-farm GHG sources associated with dairy production until milk is sold from the farm in kilograms of carbon dioxide equivalents (CO2-eq) and allocated emissions between milk and meat. The carbon footprint of milk was calculated by expressing GHG emissions attributed to milk per tonne of energy-corrected milk (ECM). The comparison showed that when GHG emissions were only attributed to milk, the carbon footprint of milk from the Irish grass-based system (837 kg of CO2-eq/t of ECM) was 5% lower than the UK confinement system (884 kg of CO2-eq/t of ECM) and 7% lower than the US confinement system (898 kg of CO2-eq/t of ECM). However, without grassland carbon sequestration, the grass-based and confinement dairy systems had similar carbon footprints per tonne of ECM. Emission algorithms and allocation of GHG emissions between milk and meat also affected the relative difference and order of dairy system carbon footprints. For instance, depending on the method chosen to allocate emissions between milk and meat, the relative difference between the carbon footprints of grass-based and confinement dairy systems varied by 3 to 22%. This indicates that further harmonization of several aspects of the LCA methodology is required to compare carbon footprints of contrasting dairy systems. In comparison to recent reports that assess the carbon footprint of milk from average Irish, UK, and US dairy systems, this case study indicates that top-performing herds of the respective nations have carbon footprints 27 to 32% lower than average dairy systems. Although differences between studies are partly explained by methodological inconsistency, the comparison suggests that potential exists to reduce the carbon footprint of milk in each of the nations by implementing practices that improve productivity