Ryegrass Pasture Research Articles

A sensory additive alters grazing behavior and increases milk response to concentrate supplementation in dairy cows

The aim of this study was to evaluate the effect of a sensory additive, incorporated into a starch-based concentrate, on milk production and composition and grazing behavior in pasture- fed dairy cows. Forty-five Holstein cows were used in 15 incomplete 3 × 2 Latin squares conducted concurrently with 3 treatments and 2 periods of 28 d At the beginning of the study, cows averaged 60 ± 17.1 d in milk, 2.2 ± 1.51 parity, 27.5 ± 4.52 kg/d of milk, and 504 kg ± 61.9 of BW (mean ± SD). Cows were assigned to the 15 squares by parity, milk yield, d in milk, and BW and within squares randomly assigned to 3 concentrate treatments that were 1 kg/d of a mineral concentrate (MC), 7 kg/d of a starch-based concentrate (CC), and 7 kg/d of CC supplemented with 30 g/d of a sensory additive (PEC; ProEfficient, Lucta SA, Barcelona, Spain). Cows grazed a perennial ryegrass pasture (Lolium perenne L.) offered at a daily allowance of 30 kg of DM per cow. Supplementation with the starch-based concentrate increased (P < 0.05) milk yield 4.4 kg/d compared with MC (24.3 .vs. 28.7 kg/d), whereas cows supplemented with PEC produced more (P < 0.05) milk and energy-corrected milk than CC cows (0.6 and 1.6 kg/d, respectively). As a result, milk response to concentrate supplementation (kg milk/kg concentrate) was improved by PEC. Additionally, PEC increased (P < 0.05) milk protein percentage (3.74 vs. 3.43%) and yield (1.08 vs. 0.98 kg/d) compared with CC. Concentrate supplementation increased (P < 0.05) total DMI, but reduced (P < 0.05) total daily grazing time (GT) and biting rate (BR) in the evening. Compared with CC, PEC did not affect (P > 0.05) total and pasture DMI but increased (P < 0.05) GT during the first 2 h after the a.m. milking as well as BR and ruminating time during the diurnal hours. The plasma concentration of active ghrelin was similarly reduced (P < 0.05) by CC and PEC after 2 h of grazing. In summary, supplementation of a starch-based concentrate with a sensory additive improved milk and protein responses of dairy cows grazing a ryegrass pasture.

Oat silage for grazing dairy cows in small-scale dairy systems in the highlands of central Mexico

The objective was to evaluate the provision of oat silage (Avena sativa) to supplement grazing dairy cows on pastures of perennial ryegrass (Lolium perenne), festulolium (Lolium multiflorum × Festuca pratense) and white clover (Trifolium repens) during the dry season when pasture growth is limited. The experimental design was a 3 × 3 Latin square replicated three times, with nine milking Holstein cows (mean live weight 496.2 ± 33.6 kg and daily milk yield 14.8 ± 2.8 kg cow−1) under on-farm participatory rural research. Experimental periods were 14 d. Simulated grazing samples of pasture herbage were analysed for chemical composition, sward height recorded and net herbage accumulation determined from exclusion cages. Treatments were the inclusion of oat silage at T0 = 0 kg DM cow−1 d−1 of oat silage, T3 = 3 kg DM cow−1 d−1 of oat silage, and T6 = 6 kg DM cow−1 d−1 of oat silage, plus 5.0 kg fresh weight commercial concentrate and 9 h of continuous grazing. Animal variables were milk yield and composition, live weight and body condition score. Feeding costs were calculated. Mean milk yield was 18.9 ± 0.27 kg cow−1 d−1 with no differences in animal variables (p > 0.05), but feeding costs per kilogram milk increased 25% for T3 and 50% for T6. Oat silage supplementation is only viable under difficult grazing conditions.

Effect of concentrate feeding level on methane emissions, production performance and rumen fermentation of Jersey cows grazing ryegrass pasture during spring

Dietary supplementation has been well documented as an effective enteric methane (CH4) mitigation strategy. However, limited studies have demonstrated the effect of concentrate level on enteric CH4 emissions from grazing dairy cows, and to our knowledge none of these studies included a pasture-only diet or reported on rumen fermentation measures. Sixty multiparous (4.0 ± 1.51 SD) Jersey cows, of which six were rumen-cannulated, were used in a randomised complete block design, and the cannulated cows were used in a separate replicated 3 × 3 Latin square design, to investigate the effect of concentrate supplementation (0, 4, and 8 kg/cow per day; as fed) on enteric CH4 emissions, milk production, dry matter intake (DMI), and rumen fermentation of dairy cows grazing perennial ryegrass pasture during spring, following a 14-d adaptation period. The sulphur hexafluoride tracer gas technique was used to measure enteric CH4 emissions from 10 cows of each treatment group over a single 9-d measurement period. Parallel with the CH4 measurement period, pasture DMI was determined using TiO2 and indigestible neutral detergent fibre as external and internal markers, respectively, while milk yield, milk composition, cow condition, and pasture pre- and post-grazing measurements were also recorded. Total DMI (13.4 to 18.0 kg/d), milk yield (12.9 to 19.2 kg/d), energy corrected milk (14.6 to 20.7 kg/d), milk lactose content (46.2 to 48.1 g/kg) and gross energy intake (239 to 316 MJ/d) increased, while milk fat content (50.0 to 44.2 g/kg) decreased with increasing concentrate feeding level. Volatile fatty acid concentrations and ruminal pH were mostly unaffected by treatment, while dry matter disappearance decreased and NH3-N concentration increased with increasing concentrate feeding level. Methane production (258 to 302 g/d) and CH4 yield (20.6 to 16.9 g/kg of DMI) were similar for all cows, while pasture DMI (13.4 to 10.8 kg/d) and CH4 intensity (20.4 to 15.9 g of CH4/kg of milk yield) decreased linearly with increasing concentrate feeding level. Results indicate that concentrate supplementation on high quality pasture-only diets have the potential to effectively reduce CH4 emissions per unit of milk yield from grazing cows during spring.

Short communication: Concentrate supplementation strategies in ryegrass pasture for productive performance in lambs

This study evaluated the effect of two concentrate supplementation strategies on performance, metabolic profile and economic evaluation of suckling lambs and ewes in ryegrass (Lolium multiflorum) pasture. Twenty-seven ewes and 45 lambs were divided into three groups: (1) ryegrass pasture without supplementation - control (CON); (2) CON plus supplemented ewes and lambs at 1% of live weight (SEL), and (3) CON plus creep feeding supplemented lambs at 1% of live weight (CSL). Concentrate use increased (p&lt;0.05) average daily gain (ADG) by 19.95% over CON (21.6 and 18.3% for SEL and CSL, respectively). Concentrate use contributed to minimizing forage quality fluctuation and provided greater ADG stability, mainly when ryegrass nutritional content and digestibility decreased. Blood metabolites profiles did not differ between groups, with exception of phosphorus which was higher for CON than SEL, and calcium which was higher for CSL than CON (p&lt;0.05). Compared to CON, stoking rate values were greater to SEL (p&lt;0.05). Compared to CSL, ewe and total stocking rate were greater (p&lt;0.05) to SEL. Considering the control group as break even feed investment, SEL strategy had a positive economic return, while CSL showed economic losses. Concentrate use increased ADG of lambs and decrease the impact of nutrient quality changes of forage on daily gains, but must be considered that supplemental strategy used could affect negatively economic return.

Rotatinuous stocking: A grazing management innovation that has high potential to mitigate methane emissions by sheep

To test the hypothesis that the best sward structure in the grazing management strategy based on animal behaviour, called ?Rotatinuous? stocking, results in higher nutrient intake and lower methane emission and intensity by sheep grazing Italian ryegrass pastures, two grazing management strategies were studied: the traditional rotational stocking (RT) with pre- and post-grazing sward target heights of 25 and 5 cm, respectively and, ?Rotatinuous? stocking (RN) with pre- and post-grazing sward target heights of 18 and 11 cm, respectively. Male castrated sheep were used. The experiment was carried out in 2014 and 2015 in southern Brazil. The experimental design was a randomized complete block with four replicates. The RN treatment had better herbage chemical composition in terms of quality than that of the RT treatment, with greater (P < 0.05) crude protein and lower neutral and acidic detergent fibre. The ideal sward structure and greater chemical composition of Italian ryegrass pastures found under RN treatment resulted in greater herbage digestibility and intake of organic matter and metabolizable energy by grazing sheep than under the RT treatment. Our study highlights that management is the key strategy to reduce the environmental impact of grazing through lower CH4 emissions in livestock grazing systems. Rotatinuous: stocking was the more efficient grazing management strategy for mitigation of CH4 emissions and intensity by grazing sheep, with 64% less CH4 production per area and 170% less CH4 emission per unit of animal product when compared to the RT treatment.

The effect of temperate or tropical pasture grazing state and grain-based concentrate allocation on dairy cattle production and behavior

Grain-based concentrate (GBC) supplement is of high cost to dairy farmers as a feed source as opposed to grazed pasture. Milk production response to GBC is affected by the composition and nutritive value of the remainder of the diet, animal factors, and interactions between forage type and level of GBC. In grazing systems, dairy cattle encounter contrasting pasture states, primarily because the social structure of the herd affects the timing of when each animal accesses a paddock after milking as a result of a relatively consistent cow milking order. However, the effect of feed management, namely pasture state and GBC allocation, on dairy cattle production and behavior is unknown. We examined the effect of varying GBC allocation for dairy cattle grazing differing states of kikuyu grass (Pennisetum clandestinum, a tropical pasture species; experiment 1) and annual ryegrass (Lolium multiflorum L., a temperate pasture species; experiment 2) on dry matter intake, milk production and composition, and grazing behavior. For each experiment, 90 lactating dairy cattle were randomly allocated to 2 consistent (fresh-fresh and depleted-depleted) and 2 inconsistent (fresh-depleted and depleted-fresh pasture state treatments (defined as sequences of pasture state allocation for the morning and afternoon grazing events) and 3 GBC treatments [2.7, 5.4, and 8.1 kg of dry matter (DM)/cow per day], giving 12 treatment combinations for each experiment. The duration of each experiment was 14 d, with the first 7 d used as adaptation to treatment. In each experiment, 3 cattle were selected from each of the 12 pasture type × GBC treatment groups within the experimental herd to determine herbage intake and total DM digestibility using the n-alkanes method (n = 36). There was no interaction between kikuyu grass or ryegrass pasture state and GBC level for intake, digestibility, or milk yield or components. Dairy cattle offered fresh-fresh and depleted-fresh ryegrass produced 9% more milk yield, in line with greater pasture intakes, compared with fresh-depleted and depleted-depleted pasture states. Dairy cattle offered fresh-fresh kikuyu grass had 8% more milk yield and 14% more milk protein yield than other pastures states, but there was no effect of pasture state on milk composition. Milk yield increased with GBC level for both pasture species (∼0.7-0.8 kg of milk/kg of DM GBC) as GBC level increased from 2.5 to 5.4 kg of DM/cow per day. There was a poor response (0.3 kg of milk/kg of DM GBC), and no response, when GBC levels increased from 5.4 to 8.1 kg of DM/cow per day for kikuyu grass and ryegrass, respectively, in line with pasture DMD. Time spent grazing, lying, and ruminating were not associated with kikuyu grass pasture state, GBC, or their interaction. Despite this, there was a linear increase in grazing time in the afternoon coinciding with a linear decrease in lying and rumination time for both kikuyu grass and ryegrass pasture. Together these findings reveal the effect of pasture state and GBC allocation on dairy cattle production and behavior. Tailoring GBC allocation to the state of pasture accessed by cattle appears unwarranted, but there is an opportunity to alter the timing of pasture access to increase herd-level milk production efficiency.

SOYBEAN CULTIVATION IN A CROP-LIVESTOCK SYSTEM WITH Azospirillum brasilense INOCULATION

ABSTRACT The objective of this study was to evaluate the phytomorphological parameters of soybean in a crop-livestock system inoculated with Azospirillum brasilense. The experiment was conducted in Santa Maria, Brazil, for two agricultural years (2 Paper extracted from the doctoral thesis of the first author. 012/2013 and 2013/2014) in a randomized complete block design with three replications. In the winter, the black oat and ryegrass pasture was managed with sheep under different grazing systems: (I) - a conventional grazing (CG) system, where the animals remained in the pasture throughout the experimental period without any pasture height control; (II, III, and IV) - systems with post-grazing pasture heights of 10, 20, and 30 cm, respectively; and (NG) - one control without grazing. All treatments received two nitrogen doses (50 and 100 kg ha-1) and inoculation or no inoculation (A. brasilense). The soybean cultivar BMX Potência RR was sown using no-tillage on 16 November 2012 and 1 December 2013. In each plot, seven rows of plants with spacing of 0.45 m were used, and in four rows, the seeds were inoculated with the bacterium A. brasilense. The phytomorphological variables and grain productivity were evaluated. In a croplivestock system, soybean has better productivity when established on black oat and ryegrass pasture managed with post-grazing pasture heights of between 20 and 30 cm. Areas under conventional grazing in the winter led to smaller soybean plants with lower first and last pod heights. Inoculation with A. brasilense should not be used alone in soybean cultivation.

Milk yield and urinary-nitrogen excretion of dairy cows grazing forb pasture mixtures designed to reduce nitrogen leaching

The effect of including a mixture of forbs in a standard perennial ryegrass-white clover pasture, with or without Italian ryegrass was investigated in a two-period grazing study comparing urinary nitrogen (N) excretion and milk yield of dairy cows in late lactation. Forty-eight mixed age, Holstein Friesian x Jersey cows were assigned to replicated, balanced, groups of six and offered one of four pasture treatments. Pasture types were either a perennial ryegrass-based pasture (PRG) with white clover or a forb-containing mixed pasture (MIX) including perennial ryegrass, white clover, chicory, plantain and lucerne. A second factor was the inclusion of Italian ryegrass (PRG+I and MIX + I). During Period I, ten cows in each of the MIX and PRG treatments were fitted with urine sensors to measure urine N parameters (urination frequency, volume and N concentration). During Period II, milk yield was measured from cows on all four pasture types. In both the ryegrass and forb pasture types, legume content exceeded 30% of the DM and in forb pastures chicory and plantain accounted for over 30% of the DM. Italian ryegrass in the MIX + I and PRG+I was respectively 5% and 15% of the DM. Digestibility and crude protein was similar for all pasture types, but fibre content was lower for forb pastures. During Period I, there was no effect of pasture type on the amount of N per urination event (averaged 13gN/event) and daily urine-N excreted (190gN/cow/day). However, pasture type affected the diurnal pattern in urine-N excretion with MIX pastures having a lower urine N loading per event during the day and higher urine N loading at night compared with PRG pastures. During Period II, milk yield was greater for forb compared with ryegrass pasture types (1.66 vs 1.50kg MS/cow/d). There was no effect of Italian ryegrass on milk yield due to low botanical content. This study demonstrated that forb containing pastures altered the diurnal pattern in urine-N excretion and offers opportunities to mitigate N leaching from grazed pastures whilst supporting high milk production in late lactation.

Impact of Rotational Grazing Systems on the Pasture Crop Coefficient for Irrigation Scheduling

AbstractCrop coefficient (Kc) estimations of ryegrass pasture (Lolium perenne) that matches the actual plant canopy represented by height (h) in rotational grazing systems have been assessed. This study investigated the impacts of grazing rotations on Kc, using non‐weighing percolation lysimeters. The FAO Penman–Monteith equation was used to estimate the reference evapotranspiration (ETr) from daily weather data. A water balance approach was applied to drainage data from 20 lysimeters to calculate actual evapotranspiration (ETa). Based on ETa and ETr, Kc was estimated for the different pasture growth stages of a grazing rotation.Results showed that Kc and h can be modelled by a linear relationship. Pre‐ and post‐grazing pasture heights were typically 30 and 10 cm, respectively, for which estimated Kc values were 1.0 and 0.6, respectively. Thus, due to variations in pasture height at different grazing stages, the conventional irrigation scheduling using a single Kc of 1.0 does not take into account the dynamic water demand for rotationally grazed pasture. Irrigation scheduling that incorporates variations in Kc with pasture growth stage will lead to more efficient water use and importantly less drainage and overland flow, perhaps the biggest environmental challenge for pastoral irrigators in New Zealand, without impacting on productivity. Copyright © 2018 John Wiley &amp; Sons, Ltd.

Effect of selected plant species within biodiverse pasture on in vitro fatty acid biohydrogenation and tissue fatty acid composition of lamb

The effect of botanical diversity on supply of polyunsaturated fatty acids (PUFA) to ruminants in vitro, and the fatty acid (FA) composition of muscle in lambs was investigated. Six plant species, commonly grown as part of UK herbal ley mixtures (Trifolium pratense, Lotus corniculatus, Achillea millefolium, Centaurea nigra, Plantago lanceolata and Prunella vulgaris), were assessed for FA profile, and in vitro biohydrogenation of constituent PUFA, to estimate intestinal supply of PUFA available for absorption by ruminants. Modelling the in vitro data suggested that L. corniculatus and P. vulgaris had the greatest potential to increase 18:3n-3 supply to ruminants, having the highest amounts escaping in vitro biohydrogenation. Biodiverse pastures were established using the six selected species, under-sown in a perennial ryegrass-based sward. Lambs were grazed (~50 days) on biodiverse or control pastures and the effects on the FA composition of musculus longissimus thoracis (lean and subcutaneous fat) and musculus semimembranosus (lean) were determined. Biodiverse pasture increased 18:2n-6 and 18:3n-3 contents of m. semimembranosus (+14.8 and +7.2 mg/100 g tissue, respectively) and the subcutaneous fat of m. longissimus thoracis (+158 and +166 mg/100 g tissue, respectively) relative to feeding a perennial ryegrass pasture. However, there was no effect on total concentrations of saturated FA in the tissues studied. It was concluded that enhancing biodiversity had a positive impact on muscle FA profile reflected by increased levels of total PUFA.

The effect of dried apple pomace as a replacer for maize in the concentrate for Jersey cows grazing ryegrass pasture on production and rumen metabolism

Ryegrass pasture is characterised as having a high crude protein content (214–298g/kg DM) but a low fibre content (390–550g NDF/kg DM). Additional supplementation of energy based concentrates is provided to ensure profitable milk production. The high starch content in these supplements could negatively impact the rumen environment; lowering rumen pH and inhibiting pasture degradability. Dried apple pomace (DAP) is a possible alternative energy source to maize for dairy cows grazing pasture; however, little information is available on the effectiveness of this high fibre by-product for milk production from pastures. The aim of this study was to determine the potential use of DAP as an energy source for Jersey cows grazing ryegrass pasture. Seventy six lactating Jersey cows were blocked according to milk yield, days in milk and lactation number. Cows within blocks were randomly allocated to one of four treatments. Treatments were: NDAP-0% dried apple pomace and 75% maize; LDAP-25% dried apple pomace and 50% maize; MDAP-50% dried apple pomace and 25% maize; HDAP-75% dried apple pomace and 0% maize. Cows received 6kg as is of the allocated concentrate in the milking parlour daily. Cows of all four treatments strip grazed perennial ryegrass pasture over an area of 8.6ha. Additionally, four ruminally cannulated cows were used to monitor treatment effect on rumen activity and health. Each cow was randomly allocated to one of four treatments and subjected to a four period crossover. The 4% fat corrected milk yield was lower for cows in treatment HDAP than for cows in treatments NDAP and LDAP, differences ranging between 1.7 and 2.3kg/day. The milk protein content was lowest for cows in treatments NDAP and MDAP, showing a cubic trend (P=0.005), with milk fat content increasing as the level of maize substituted by DAP increased. Treatment had no effect on rumen metabolism parameters. Replacing maize with DAP is a viable option for cows grazing ryegrass pasture; however, the decrease in 4% fat corrected milk yield and the potential economic impact should not be overlooked.

The performance of single-rearing ewes and their lambs offered ryegrass pasture or herb–clover mix during lactation

ABSTRACTLamb growth to weaning has important implications for the profitability of farms producing lambs for meat. Alternative forage crops such as chicory, plantain, red clover and white clover have the potential to increase lamb growth rates to weaning percentage sold to slaughter at weaning. A study was conducted over two years to examine the growth of single-born lambs offered either pasture or herb-mix (chicory, plantain, white clover and red clover) from birth to weaning. Each year, 80 single-bearing ewes were allocated to either a pasture or herb-clover mix. In 2014, ewes and lambs that were offered the herb-clover mix had greater live weights at weaning than those grazed on ryegrass pasture. In 2015, however, no differences in lamb weaning weight was observed. In both years of the study, lambs reared on the herb clover mix had growth rates in excess of 400 g/day, from birth to weaning.

High perennial ryegrass seeding rates do not negatively impact pasture sward persistence

AbstractPoor persistence of perennial ryegrass swards is a common problem; however, there is a lack of long‐term studies to understand the mechanisms associated with poor persistence. This study describes an experiment to test the hypothesis that high ryegrass seeding rates (&gt;18 kg seed per ha) reduce long‐term population persistence because of smaller plant size and poorer survival during the first year after sowing. Four cultivars, representing four functional types of perennial ryegrass, were sown at five seeding rates (equivalent to 6, 12, 18, 24 and 30 kg seed per ha) with white clover in three regions of New Zealand. Swards were monitored for 5 years. No evidence was found to indicate a lack of persistence of ryegrass‐based swards sown at higher seeding rates. During the first year, swards sown at higher seeding rates had greater herbage accumulation (except at the Waikato site), greater ryegrass tiller density and greater ryegrass content. This initial impact of high seeding rates had largely dissipated by the fourth year, resulting in swards with similar annual herbage accumulation, tiller density and botanical composition. Similarly, there were relatively few differences among cultivars for these variables. Although high seeding rates did not negatively impact sward persistence, geographical location did, with strong evidence of ryegrass population decline at the Waikato site for all treatment combinations, some decline in Northland, and stable populations in Canterbury. It is possible that productive perennial ryegrass pastures can only be sustained for 4–5 years in some situations, even when the best ryegrass technology and management practices are used.

Biomass flows and defoliation pattern of ryegrass grazed by supplemented heifers

To strategically define the best stocking rate management strategy for ryegrass, it is important to know the growth process of forage plants in detail. The study was conducted to analyze the leaf biomass flows and the defoliation intensity and frequency of Italian ryegrass (Lolium multiflorum Lam) grazed by heifers fed exclusively on pasture or on pasture and supplemented with corn or white oat grain. The experimental design was completely randomized following a repeated measures arrangement with three feeding systems and three area replications. Biomass flows (kg DM leaf blades ha1 day1) for leaf growth (40.6), leaf senescence (40.7), and leaf intake (29.7) were similar in the different feeding systems. Leaf blade intake adjusted to body weight was lower in supplemented heifers regardless of grain type. Actual and potential utilization efficiencies and ryegrass biomass net balance were not affected by feeding system. The leaf intake flow was 1.4 times lower than the growth flow, resulting in an actual utilization efficiency less than one (0.7), whereas the senescence flow was higher than the growth flow, resulting in a negative potential utilization efficiency (0.2). Leaf defoliation intensity was similar (54.4%) across feeding systems and defoliation frequency was higher in supplemented heifers. The 29.2% increase in stocking rate of heifers fed corn or oat grain as supplement did not affect the dynamics of ryegrass biomass flows, but reduced leaf blade intake adjusted to heifer body weight leading to alterations in the defoliation frequency of ryegrass pasture.

Outdoor grazing of dairy cows on pasture versus indoor feeding on total mixed ration: Effects on gross composition and mineral content of milk during lactation

The influence of feeding system and lactation period on the gross composition, macroelements (Ca, P, Mg, and Na), and trace elements (Zn, Fe, Cu, Mo, Mn, Se, and Co) of bovine milk was investigated. The feeding systems included outdoor grazing on perennial ryegrass pasture (GRO), outdoor grazing on perennial ryegrass and white clover pasture (GRC), and indoors offered total mixed ration (TMR). Sixty spring-calving Holstein Friesian dairy cows were assigned to 3 herds, each consisting of 20 cows, and balanced with respect to parity, calving date, and pre-experimental milk yield and milk solids yield. The herds were allocated to 1 of the 3 feeding systems from February to November. Milk samples were collected on 10 occasions over the period June 17 to November 26, at 2 or 3 weekly intervals, when cows were on average 119 to 281 d in lactation (DIL). The total lactation period was arbitrarily sub-divided into 2 lactation periods based on DIL, namely mid lactation, June 17 to September 9 when cows were 119 to 203 DIL; and late lactation, September 22 to November 26 when cows were 216 to 281 DIL. With the exception of Mg, Na, Fe, Mo, and Co, all other variables were affected by feeding system. The GRO milk had the highest mean concentrations of total solids, total protein, casein, Ca, and P. The TMR milk had the highest concentrations of lactose, Cu, and Se, and lowest level of total protein. The GRC milk had levels of lactose, Zn, and Cu similar to those of GRO milk, and concentrations of TS, Ca, and P similar to those of TMR milk. Lactation period affected all variables, apart from the concentrations of Fe, Cu, Mn, and Se. On average, the proportion (%) of total Ca, P, Zn, Mn, or Se that sedimented with the casein on high-speed ultracentrifugation at 100,000 × g was ≥60%, whereas that of Na, Mg, or Mo was ≤45% total. The results demonstrate how the gross composition and elemental composition of milk can be affected by different feeding systems.

Replacing maize grain with dried citrus pulp in a concentrate feed for Jersey cows grazing ryegrass pasture

CITATION: Steyn, L., Meeske, R. & Cruywagen, C. W. 2017. Replacing maize grain with dried citrus pulp in a concentrate feed for Jersey cows grazing ryegrass pasture. South African Journal of Animal Science, 47(4):553-564, doi:10.4314/sajas.v47i4.14.

522 Evaluation of oats incorporated into annual ryegrass on performance of beef cattle

Forty crossbred beef steers (204.1 + 18.9 kg BW) were used in a randomized complete block to determine the effects of incorporating oats (Avena sativa) into annual ryegrass (Lolium multiflorum) pastures. Ten warm-season perennial pastures (1.21 ha) were killed with glyphosate and then burned, after which pastures were scratched with a disk. Pastures were randomly assigned to 1 of 2 treatments: 1) oats drilled into the pasture at a depth of 2.54 cm, at a rate of 90 kg/ha, after which annual ryegrass was broadcast at the rate of 56 kg/ha (OATS) or 2) annual ryegrass broadcast at the rate of 56 kg/ha (RG). Fertilization rates and application were similar across both treatments. When pastures had sufficient forage to support 4 beef cattle (5 kg forage DM/kg of BW), cattle were weighed and then moved into pastures. Forage biomass was determined weekly with the use of a rising plate reader, and when forage became limiting (less than 5 kg of forage DM/kg of BW), cattle were weighed and then removed. Between forage grazing periods, cattle had access to a commercial feed supplement and dormant forage. Pasture cost of establishment per hectare was greater for OATS (P= 0.001; US$332.5 and $219.7 for OATS and RG, respectively). Average daily gain did not differ (P= 0.90) between treatments (1.00 vs. 0.99 kg/d for OATS and RG, respectively. Pastures planted with OATS had more grazing days (124 vs. 98) and overall greater gain per pasture (P= 0.003; 383.8 kg compared with 291.6 kg for OATS and RG, respectively). Pasture-only cost of gain was similar (P= 0.24) for both OATS and RG; however, when the cost of supplementation (when not grazing) was factored into the overall cost of gain, OATS had a more economical cost of gain compared with RG (P= 0.002). Results suggest incorporation of a small grain such as oats may increase the winter grazing period and reduce cost of gain.

Effects of multiple oral administrations of fenbendazole on growth and fecal nematodes infection of early-weaned beef calves grazing perennial, warm-season or annual, cool-season grasses

Two experiments evaluated growth and total fecal egg count (FEC) of early-weaned calves receiving multiple or a single oral drench of fenbendazole while grazing warm- or cool-season grasses. On d 0, Brangus crossbred calves (n = 64 and 56 in Exp. 1 and 2, respectively) were allocated into bahiagrass or ryegrass pastures (6 to 8 pastures per forage system; 4 calves per pasture). Thereafter, 2 of 4 calves within each pasture (Exp. 1) or all calves in each pasture (Exp. 2) received oral administration of fenbendazole (5 mg/kg of BW) every 28 d from d 0 to 84 (MULT) or once on d 56 (CTRL). Overall ADG from d 0 to 84 increased (P = 0.01; Exp. 1) or tended to increase (P = 0.11; Exp. 2) for MULT versus CTRL calves. In Exp. 1, FEC on d 28 and 56 was less (P ≤ 0.05) for MULT versus CTRL, but the reduction on FEC was greater for MULT calves grazing ryegrass versus bahiagrass (P < 0.001). Fenbendazole treatment on d 56 reduced FEC on d 84 versus 56, but FEC remained greater for CTRL calves grazing bahiagrass than all calves grazing ryegrass (P ≤ 0.03; Exp. 1). In Exp. 2, FEC of MULT calves decreased on d 28 and 56 (P ≤ 0.10) and achieved similar values in d 84 than CTRL calves (P = 0.93). Therefore, monthly oral administrations of fenbendazole improved ADG of early-weaned calves, regardless of forage system, compared with a single, strategic administration on d 56 after weaning.

乳牛の集約的放牧について : 第2報 イタリアンライグラス草地に放牧した乳牛の養分摂取量について

乳牛の集約的放牧について : 第2報 イタリアンライグラス草地に放牧した乳牛の養分摂取量について

The use of oxidative stress biomarkers in live animals (in vivo) to predict meat quality deterioration postmortem (in vitro) caused by changes in muscle biochemical components1

This study was conducted to determine whether circulating concentrations of blood isoprostanes can be used as an effective biomarker in lambs to predict degradation of color and/or lipid stability in meat. Lambs ( = 84) were fed diets of either lucerne pasture, annual ryegrass pasture, a commercial feedlot pellet, or a combination of annual ryegrass and feedlot pellet for 8 wk, including a 2-wk adaptation period. Blood isoprostane concentration at wk 0, 4, 6 or 8 of feeding was determined. Blood isoprostane concentration for each animal was then correlated with muscle biochemical components that impact color and/or lipid oxidative status during retail display. This included lipid oxidation levels in muscle assessed by thiobarbituric acid reactive substances and meat redness determined by a HunterLab colorimetric spectrometer. Lambs that consumed the commercial feedlot pellet had a lower muscle vitamin E level (< 0.01) and a greater level of -6 PUFA ( < 0.001) compared with lambs finished on annual ryegrass or lucerne. Lipid oxidation levels were greatest for lambs finished on the feedlot ration, lowest in lambs finished on the ryegrass diet, and intermediate for lambs finished on lucerne and ryegrass-feedlot combination ( < 0.01). After 8 wk of feeding, blood isoprostane concentration was positively correlated with lipid oxidation of meat displayed for 72 h in simulated retail conditions ( < 0.01). There was a negative linear relationship between isoprostane concentration and muscle vitamin E concentration ( = 0.07), lipid oxidation and muscle vitamin E concentration ( < 0.01) but a positive linear relationship between isoprostane concentration and muscle -6 PUFA ( < 0.001) or lipid oxidation and muscle -6 PUFA concentration ( < 0.001). Blood isoprostane concentration and lipid oxidation in meat were influenced by muscle vitamin E and -6 PUFA but not by -3 PUFA. There was no significant relationship observed between blood isoprostane concentration at 0, 4, 6 or 8 wk feeding vs. overall meat color (redness of meat) at 0 and 72 h of display, stored under simulated retail conditions. The results indicate that circulating blood isoprostane concentration can be a useful tool to predict the oxidative status of postmortem meat. Future work will examine the impact of this relationship on meat flavor/aroma deterioration post farm.