Two experiments were carried out to examine the effects of high quality pasture and high-concentrate diets on liveweight and carcass gain of beef cattle, carcass composition at equal carcass gain, and the fatty acid composition of beef. Heifers of late-maturing breed type (406 kg initial liveweight; Experiment 1) and steers of latematuring breed type (460 kg initial liveweight; Experiment 2) were finished on a ryegrass pasture or a high-concentrate diet at either (1) ad libitum, (2) 85% of ad libitum intake or (3) 70% of ad libitum intake. The high-concentrate diet consisted of 95% barley-based concentrate and 5% barley straw. Carcass gain of the animals finished at pasture (648 g day -1 ) was 0.78 in Experiment 1 (P < 0.001) and 0.88 in Experiment 2 (P > 0.1) of that of the animals given the high-concentrate diet ad libitum. Gains in lean meat were similar for animals finished at pasture and those given concentrates ad libitum, whereas daily fat gains were 39% lower for the animals finished at pasture (P < 0.001). At an equal rate of carcass gain, animals finished at pasture produced carcasses with a higher lean content (P = 0.03) and a lower fat content (P = 0.03) than those produced from the high-concentrate diet. Muscle from pasture-finished cattle had higher concentrations of omega-3 polyunsaturated fatty acids (PUFA) (141 versus 49 ± 8.2 mg 100 g -1 muscle) and long-chain omega-3 PUFA (58 versus 27 ± 3.8 mg 100 g -1 muscle) than muscle from concentrate-fed cattle. These results highlight the potential of high quality ryegrass pasture for finishing cattle, and meat from pasturefinished cattle as a source of omega-3 PUFA.

Background Leukostasis is a key patho-physiological event responsible for capillary occlusion in diabetic retinopathy. Circulating monocytes are the main cell type entrapped in retinal vessels in diabetes. In this study, we investigated the role of the signal transducer and activator of transcription 3 (STAT3) pathway in diabetes-induced immune cell activation and its contribution to retinal microvascular degeneration. Methods Forty-one patients with type 1 diabetes (T1D) [mild non-proliferative diabetic retinopathy (mNPDR) ( n = 13), active proliferative DR (aPDR) ( n = 14), inactive PDR (iPDR) ( n = 14)] and 13 age- and gender-matched healthy controls were recruited to the study. C57BL/6 J WT mice, SOCS3 fl/fl and LysM Cre/+ SOCS3 fl/fl mice were rendered diabetic by Streptozotocin injection. The expression of the phosphorylated human and mouse STAT3 (pSTAT3), mouse LFA-1, CD62L, CD11b and MHC-II in circulating immune cells was evaluated by flow cytometry. The expression of suppressor of cytokine signalling 3 (SOCS3) was examined by real-time RT-PCR. Mouse plasma levels of cytokines were measured by Cytometric Beads Array assay. Retinal leukostasis was examined following FITC-Concanavalin A perfusion and acellular capillary was examined following Isolectin B4 and Collagen IV staining. Results Compared to healthy controls, the expression of pSTAT3 in circulating leukocytes was statistically significantly higher in mNPDR but not aPDR and was negatively correlated with diabetes duration. The expression of pSTAT3 and its inhibitor SOCS3 was also significantly increased in leukocytes from diabetic mice. Diabetic mice had higher plasma levels of IL6 and CCL2 compared with control mice. LysM Cre/+ SOCS3 fl/fl mice and SOCS3 fl/fl mice developed comparative levels of diabetes, but leukocyte activation, retinal leukostasis and number of acellular capillaries were statistically significantly increased in LysM Cre/+ SOCS3 fl/fl diabetic mice. Conclusion STAT3 activation in circulating immune cells appears to contribute to retinal microvascular degeneration and may be involved in DR initiation in T1D. Electronic supplementary material The online version of this article (10.1186/s12974-019-1533-1) contains supplementary material, which is available to authorized users.

It is now well established that finishing diets for beef cattle containing a high proportion of grass silage produce lower growth rates and a greater proportion of fat in the gain than high-concentrate diets offered at the same energy input. However, a major proportion of beef cattle in the British Isles are finished off grass and there is little information on the carcass composition of grass-finished cattle relative to those finished on high-concentrate diets. Two comparative slaughter experiments involving both steers and heifers have been carried out to compare grazed grass and concentrate diets in terms of performance and carcass composition at equal levels of performance.

It is now well established that finishing diets for beef cattle containing a high proportion of grass silage produce lower growth rates and a greater proportion of fat in the gain than high-concentrate diets offered at the same energy input. However, a major proportion of beef cattle in the British Isles are finished off grass and there is little information on the carcass composition of grass-finished cattle relative to those finished on high-concentrate diets. Two comparative slaughter experiments involving both steers and heifers have been carried out to compare grazed grass and concentrate diets in terms of performance and carcass composition at equal levels of performance.

The maintenance energy requirement of an animal can be defined as the daily metabolisable energy (ME) intake at which it is in zero energy balance. Maintenance energy requirements can be estimated either by measuring fasting metabolism or from a regression relationship between ME intake and energy retention for a number of animals given a range of ME intakes. However maintenance energy requirements may vary according to the composition of the diet, as higher intakes of high-fibre diets have promoted greater rates of gut metabolism than lower intakes of low-fibre diets. In the present study maintenance energy requirements of beef cattle and lambs have been estimated by regressions between ME intake and energy retention using data from a series of studies involving diets based on grass silage or fresh grass and concentrates.