Mixed grazing of sheep and cattle using continuous or rotational stocking

Two consecutive experiments were conducted to test a hypothesis that mixed grazing outcome is influenced by the type of stocking system applied. The objective of both experiments was to investigate the influence of co-grazing with sheep on cattle liveweight gain (LWG) under continuous (C) and rotational (R) stocking, where sheep weekly liveweight change under the two stocking systems was kept similar. In experiment I nine yearling heifers (266 ± 4.5 kg liveweight) and 27 ewe hoggets (54±0.9 kg liveweight) were continuously stocked for 19 weeks on an irrigated perennial ryegrass-white clover pasture (2.95 ha) maintained at a sward surface height (SSH) of 5cm by adding or removing additional animals in a fixed ratio (1: 1 W⁰.⁷⁵ cattle:sheep). An equal area of pasture was rotationally stocked by a similar group of animals where they received a new area of pasture daily and also had access to the grazed area over the previous 2 days. The size of the new area provided daily was such that the weekly liveweight change of rotationally co-grazed sheep was equal to that of those continuously co-grazed with cattle. Similar groups of animals were used in the second experiment with additional group of 9 heifers grazed alone on C and R pastures. Liveweight of animals was recorded weekly and final fasted weight was determined after 24-hour total feed restriction. SSH on both treatment swards was recorded daily. There were three intake measurement periods spread over the trial period. Organic matter intake (OMI) was predicted from the ratio of N-alkanes in faeces and herbage. Diet composition was determined by dissecting oesophageal extrusa samples. Grazing behaviour (bite rates and grazing time) were also recorded. The mean SSH for C pasture was 5.1±0.09 cm. Overall pre- and post-grazing SSH for R pasture was 15.9 ±0.12 and 5.6 ±0.07 cm, respectively. As determined by the protocol average daily LWG of sheep was similar between C and R (147 (±5.8) vs 138 (±6.7) g day⁻¹; (P>0.05). In contrast, cattle continuously stocked with sheep grew 200 g day⁻¹ slower than those rotationally stocked with sheep (800 (±41.6) vs 1040 (±47.7) g day⁻¹, P<0.0l). R heifers achieved 30 kg higher final fasted liveweight than C heifers (350 vs 381 kg; P<0.01). Overall LWG per ha was also 6 % higher under R than C stocking (674 vs 634 kg ha⁻¹). The OMD of both sheep (73.5 vs 75.8 %) and cattle (75.8 vs 78.0 %) diets was similar under continuous and rotational stocking. There was no significant difference OMI data also concurred with the L WG data (Cattle: 7.94 vs 6.31 (±0.32) kg day⁻¹ (P<0.05); sheep: 1.40 vs 1.44 (±0.04) kg day⁻¹ for Rand C treatments, respectively). There was no difference in clover content of cattle diet under C and R treatments. C heifers had higher number of bites per minute than R heifers (62 vs 56; P<0.05). Proportion of heifers seen grazing (every 15-minute) during four 24-hour observations was greater on C than R pasture (0.44 vs 0.31 (±0.03); P<0.05). The similarity coefficient between sheep and cattle diet was 0.61 and 0.76 under C and R stocking, respectively. The lower daily LWG of C heifers was attributed to (a) the lower SSH under C than R stocking and/or (b) the inability of cattle to compete well with sheep where there is small, continual renewal of resources (C) in contrast to a large periodic renewal under R stocking. This experiment showed that the outcome of mixed gruing can be influenced by the stocking system chosen. But it was not possible to apportion the difference in LWG of cattle between mixed grazing per se and the difference in mean grazed sward height (5.1 for C vs 10.8 cm for R). A second experiment was conducted to determine the relative performance of cattle co-grazed with sheep (CS) and grazed alone (CA) under each stocking system. Hence, there were four treatments. CA- continuous stocking (CA-C), CS- continuous stocking (CS-C), CA- rotational stocking (CAR) and CS- rotational stocking (CS-R). A total area of 4.42 ha was allocated to each stocking system. Under C stocking, 2.95 ha (2/3) was assigned to CS-C and 1.47 ha (1/3) to CA-C, and SSH on both treatments was kept at 4 cm by adding or removing extra animals. Under R stocking, CA-R and CS-R grazed side by side separated by an electric fence. They were given a fresh area daily, the size of which was varied such that the weekly LW change of R sheep was equal to that of the C sheep. CA-R received one-third of the new area though the size was adjusted regularly to achieve the same post-grazing SSH with CS-R. Measurements included: weekly liveweight change, OMI (two periods) and diet composition (using N-alkanes). The mean SSH of CA-C and CS-C swards was 4.27 and 4.26 (±0.02) cm, respectively. CA-R and CS-R swards had mean pre-grazing SSH of 14.9 and 15.2 (±0.08) cm and post-grazing heights of 4.87 and 4.82 cm (±0.03), respectively. The proportion of areas infrequently grazed was higher for CA-C than CS-C swards (0.22 vs 0.17, respectively). C and R sheep daily LWG: 155 (±0.6) and 147 (±0.7) g, and OMI: 1.96 and 2.04 (±0.ll) kg, respectively, were not significantly different. They also had similar diet composition. In comparison, CS-C heifers grew only at 69 % of the daily LWG achieved by CS-R heifers (706 vs 1028 (±72) g; P0.05). Differences in OMI followed a similar pattern to daily LWG. Mean daily OMI was 8.98, 6.24, 8.80 and 9.45 (±0.40) kg for CA-C, CS-C, CA-R and CS-R, respectively. Clover content of the diet of CA-C heifers was three times higher than that of CS-C heifers (30.7 vs 10.4 % OM; P<0.05); there was no difference in clover content of diets of CS-R and CA-R heifers (21.5 vs 23.9 % OM, respectively). In both stocking systems LWG per ha was higher on CA than CS treatments. These results suggested that the disadvantage of selective clover grazing by sheep outweighed the advantages of sheep grazing around cattle dung patches under continuous stocking. Under rotational stocking, rapid diurnal changes in sward conditions probably limited selective grazing by both sheep and cattle such that there was no disadvantage to CS cattle. The results do not provide a basis for recommending grazing cattle with sheep rather than cattle alone, but do provide some basis for recommending co-grazing of sheep and cattle using rotational rather than continuous stocking

Effects of delayed feeding, sodium butyrate and glutamine on intestinal permeability in newly-hatched broiler chickens

The aim of the current study was to investigate the effects of delayed feeding, and supplementation with sodium butyrate or glutamine in drinking water, on intestinal permeability (IP) in young broiler chickens. Newly-hatched male chickens (Ross 308) were allocated to four groups comprising Control, 24 h delayed fed (DF), DF supplemented with sodium butyrate (0.1%) in the drinking water and DF supplemented with glutamine (1%) in the drinking water. On days 2, 4 and 7, twelve birds per group were randomly selected, weighed and orally gavaged with fluorescein isothiocyanate dextran (FITC-d) at 2.2 mg / ml / chicken. Serum FITC-d concentration was analysed by spectrophotometry while serum diamine oxidase and D-lactic acid concentrations were analysed by microplate reader. FITC-d concentrations in the Control and DF groups were not statistically different on any day, suggesting that delayed feeding did not affect IP. Additionally, sodium butyrate increased IP compared to DF and Control on day 2 only (p

DHA-Containing Oilseed: A Timely Solution for the Sustainability Issues Surrounding Fish Oil Sources of the Health-Benefitting Long-Chain Omega-3 Oils

Benefits of long-chain (≥C20) omega-3 oils (LC omega-3 oils) for reduction of the risk of a range of disorders are well documented. The benefits result from eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA); optimal intake levels of these bioactive fatty acids for maintenance of normal health and prevention of diseases have been developed and adopted by national and international health agencies and science bodies. These developments have led to increased consumer demand for LC omega-3 oils and, coupled with increasing global population, will impact on future sustainable supply of fish. Seafood supply from aquaculture has risen over the past decades and it relies on harvest of wild catch fisheries also for its fish oil needs. Alternate sources of LC omega-3 oils are being pursued, including genetically modified soybean rich in shorter-chain stearidonic acid (SDA, 18:4ω3). However, neither oils from traditional oilseeds such as linseed, nor the SDA soybean oil have shown efficient conversion to DHA. A recent breakthrough has seen the demonstration of a land plant-based oil enriched in DHA, and with omega-6 PUFA levels close to that occurring in marine sources of EPA and DHA. We review alternative sources of DHA supply with emphasis on the need for land plant oils containing EPA and DHA

The nutritional value of Russell lupin (Lupinis polyphyllus x Lupinus arboreus) for sheep

Two field trials were conducted consecutively in Canterbury, at Lincoln University. In the first experiment, spring regrowth of Russell lupin (Lupinus polyphyllus x L. arboreus) was cut at three weekly intervals to determine changes in nutritive value with plant maturity. Six harvests were made between 5 October 1989 and 18 January 1990. Measurements included dry matter (DM) yield per plant and plant parts, nitrogen (N) and neutral detergent fibre (NDF) concentration, and in vitro cellulase DM and organic matter (OM) digestibility. Whole-plant DM yield for the six cuts increased from 40 to 160 g plant⁻¹ (or 4 to 16 t ha⁻¹). Up to pod formation the DM yield of Russell lupins was largely petioles and leaves. The N concentration in total DM decreased from 4.5 to 2.4% with maturity; corresponding values for NDF were 24.1 to 46.2%. This was due to both changes in the proportion of plant components and changes in N and NDF concentration within components. The N concentration in individual plant parts generally declined over time. The in vitro cellulase DM and OM digestibility declined from 76.5 to 56.0 % and 81.4 to 54.9%, respectively. Unlike most other pasture species, the in vitro cellulase DM and OM digestibilities of Russell lupin showed a slow, quadratic (P80% digestibility, and (iii) 0 and 50% of the DDM (of peak I and II respectively) consisted of plant components with <60% digestibility. This trial showed that Russell lupins can produce highly digestible DM with a high N content over most of their growth. In the second experiment, autumn sown (March, 1990) Russell lupins were grazed (Nov., 1990 - Jan., 1991) by two-tooth Coop worth ewes (plot size 418 m², 20 sheep plot⁻¹) at full bloom, green pod and dry pod stages. The objectives were: (i) to distinguish between the two stages of peak DDM yield in terms of acceptability to sheep, per cent utilisation and amount of regrowth and determine the optimum stage to graze the lupins, and (ii) to study preference of sheep among different plant components of Russell lupins. There was no apparent difference between the three stages of growth with respect to acceptability, for average DM disappeared per sheep increased with allowance. Sheep selected against stems, but showed strong preference for leaves; defoliation of other parts increased as the proportion of leaves in total herbage decreased. As opposed to earlier reports, there was significant consumption of both green and dry pods. Per cent utilisation was 89, 80 and 75% for lupins grazed at full bloom, green pod and dry pod, respectively. Total regrowth DM (residue + current growth) yield was 6960, 3774 and 2282 kg ha⁻¹ for Russell lupins grazed at full bloom, green pod and dry pod stage, respectively. However, the difference between full bloom and dry pod in terms of estimated annual harvestable (i.e. by sheep) DM yield, which respectively was 6990, 6490 and 7410 kg ha⁻¹ for lupins grazed at full bloom, green pod and dry pod stage, was not as marked. Therefore, it was concluded that the optimum stage for grazing will depend on the feed requirement plan of the individual farmer. Farmers have the option of leaving the lupins standing till late in the season without marked loss of quality, or graze them early for better autumn regrowth

Lipid-Induced Insulin Resistance in Skeletal Muscle: The Chase for the Culprit Goes from Total Intramuscular Fat to Lipid Intermediates, and Finally to Species of Lipid Intermediates

The skeletal muscle is the largest organ in the body. It plays a particularly pivotal role in glucose homeostasis, as it can account for up to 40% of the body and for up to 80%–90% of insulin-stimulated glucose disposal. Hence, insulin resistance (IR) in skeletal muscle has been a focus of much research and review. The fact that skeletal muscle IR precedes β-cell dysfunction makes it an ideal target for countering the diabetes epidemic. It is generally accepted that the accumulation of lipids in the skeletal muscle, due to dietary lipid oversupply, is closely linked with IR. Our understanding of this link between intramyocellular lipids (IMCL) and glycemic control has changed over the years. Initially, skeletal muscle IR was related to total IMCL. The inconsistencies in this explanation led to the discovery that particular lipid intermediates are more important than total IMCL. The two most commonly cited lipid intermediates for causing skeletal muscle IR are ceramides and diacylglycerol (DAG) in IMCL. Still, not all cases of IR and dysfunction in glycemic control have shown an increase in either or both of these lipids. In this review, we will summarise the latest research results that, using the lipidomics approach, have elucidated DAG and ceramide species that are involved in skeletal muscle IR in animal models and human subjects

Rise in DPA Following SDA-Rich Dietary Echium Oil Less Effective in Affording Anti-Arrhythmic Actions Compared to High DHA Levels Achieved with Fish Oil in Sprague-Dawley Rats

Stearidonic acid (SDA; C18:4n-3) has been suggested as an alternative to fish oil (FO) for delivering health benefits of C ≥ 20 long-chain n-3 polyunsaturated fatty acids (LC n-3 PUFA). Echium oil (EO) represents a non-genetically-modified source of SDA available commercially. This study compared EO and FO in relation to alterations in plasma and tissue fatty acids, and for their ability to afford protection against ischemia-induced cardiac arrhythmia and ventricular fibrillation (VF). Rats were fed (12 weeks) diets supplemented with either EO or FO at three dose levels (1, 3 and 5% w/w; n = 18 per group). EO failed to influence C22:6n-3 (DHA) but increased C22:5n-3 (DPA) in tissues dose-dependently, especially in heart tissue. Conversely, DHA in hearts of FO rats showed dose-related elevation; 14.8%–24.1% of total fatty acids. Kidney showed resistance for incorporation of LC n-3 PUFA. Overall, FO provided greater cardioprotection than EO. At the highest dose level, FO rats displayed lower (p &lt; 0.05) episodes of VF% (29% vs. 73%) and duration (22.7 ± 12.0 vs. 75.8 ± 17.1 s) than the EO group but at 3% EO was comparable to FO. We conclude that there is no endogenous conversion of SDA to DHA, and that DPA may be associated with limited cardiac benefit

Microbial Quality and Growth Dynamics in Shameta: A Traditional Ethiopian Cereal-Based Fermented Porridge

Shameta is a traditional, Ethiopian, cereal-based fermented porridge exclusively prepared for lactating mothers. The aim of this study was to determine the microbial quality of Shameta samples collected from households of lactating mothers and to determine microbial dynamics and physicochemical changes during laboratory fermentation of Shameta. Isolation and characterization of the dominant microbes and analysis of the physicochemical properties of samples were done following standard microbiological methods and analytical techniques. Results of this study showed that the highest mean count of lactic acid bacteria (8.33 log cfu/g) was recorded in a sample from laboratory-fermented barley-based Shameta, and the lowest (5.88 log cfu/g) in Shameta made from a mixture of barley and maize (BMS). In both barley-based and maize-based laboratory-prepared Shameta, the microflora were dominated by LAB, followed by yeasts. The dominant LAB were the genus Lactobacillus (74.85%), followed by Enterococcus (15.79%). It could be concluded that Shameta collected from households of lactating mothers are fairly safe for consumption, as the stringent physicochemical conditions of the final product could inhibit the growth of pathogens. However, as Shameta is a traditional fermented porridge fed to lactating mothers, we call for a further improvement to the fermentation process by using defined starter cultures