Comparing Drying Protocols for Perennial Ryegrass Samples in Preparation for Chemical Analysis

Diet formulation for animals requires accurate estimation of feed nutritive value. In order to determine the nutritive value of grass, the moisture in the samples must be removed, with minimum damage to cell structure, and then the dried samples milled, prior to chemical analysis. Generally samples are oven dried. The aim of this study was to verify if differing drying protocols gave diverging results when drying grass samples. The drying protocols investigated were 40°C for 48 hours, 60°C for 48 hours and 95°C for 15 hours in forced convection ovens. Four perennial ryegrass samples were cut to 4 cm from ground level on three occasions in 2012. On each occasion the four grass samples were mixed together thoroughly and divided into four replicates. Each replicate was divided into three sub-samples to give one 100 g-sample per drying treatment. At regular intervals the samples were removed from the oven and the weight recorded. The data were analysed using a mixed model repeated measures procedure in SAS. Time (hours) was used as the repeated measure. A separate dataset of 12 grass samples were dried using both the 40°C and 60°C protocols and then chemically analysed. This dataset was analysed using PROC GLM in SAS. Samples were assumed dry when there was no significant difference in weight between times. All drying protocols gave a similar final dry matter of approximately 156 g/kg. All drying protocols did dry the grass samples adequately as samples dried at 40°C and 60°C were not significantly lighter after 24 hours and samples dried at 95°C were not significantly lighter after 15 hours. There were no differences in ash or crude protein concentration of the samples dried using the 40°C and 60°C protocols. There were differences in the organic matter digestibility, neutral detergent fibre and acid detergent fibre concentrations between the grass samples dried using the different drying protocols

Immediate and Carryover Effects of Post-Grazing Sward Height Imposed in Early Spring on Sward and Milk Production

A grazing experiment was undertaken to investigate the immediate and carryover effect of post-grazing sward height (PGH) in early spring on sward and dairy cow production. Ninety Holstein-Friesian spring calving dairy cows were randomly assigned across 3 PGH treatments: 2.7, 3.5 and 4.2 cm from February 14 to April 24, 2011. Following the experimental period animals were managed similarly until the end of the lactation. Grazing to 2.7 cm during the experimental period reduced milk (-159 kg/cow; P \u3c 0.01) and milk solids (-16 kg/cow; P \u3c 0.01) yields and increased BW loss (+13 kg loss; P \u3c 0.05) when compared to the 3.5 and 4.2 cm treatments which performed similarly. Grass utilisation (\u3e2.7 cm) increased (P \u3c 0.001) by decreasing PGH from 4.2 cm (0.74) to 3.5 cm (0.82) and further to 2.7 cm (0.94). During the carryover period (April 24 to November 13), cumulative milk (3542 kg/cow) and milk solids (281 kg/cow) yields did not differ between the experimental treatments. End BW was similar across treatments (503 kg). Total lactation performance of cows grazing to 2.7 cm in spring was -24 kg milk solids (P \u3c 0.05) than the total lactation production of the 3.5 and 4.2 cm treatments (405 kg milk solids) indicating that cows offered a restricted pasture allowance in early lactation do not recover lost production. This study recommends a PGH of 3.5 cm in the first 2 grazing rotations to achieve a compromise between sward utilisation and animal performance in early spring while also ensuring high subsequent lactation milk production

Short-Term Milk Yield Response to Changes in Post-Grazing Sward Height

In temperate climates, grazed grass is the cheapest source of nutrients for the dairy cow (Finneran et al. 2010), therefore its utilisation should be optimised throughout the grazing season to increase enterprise profitability (Shalloo et al. 2004). Within spring-calving systems, energy requirements increase for the post-parturient dairy cow during the spring period. On the other hand, spring grass supply can be limited given low over-winter grass growth rates. The imposition of a lower post-grazing sward height (PGH) during this critical time may be a viable solution to increase grass availability. As the season progresses, PGH may be increased or decreased to adjust the allowance of grass in the dairy cow’s diet depending on farm grass supply. Quantifying the variation in animal production with changes in PGH will inform such decisions. Currently, there is no information available on the milk production response to changes in PGH over a short period of the lactation. Therefore, the aim of this experiment was to determine the short-term variation in milk yield (MY) and yields of protein, fat and lactose in response to changes in PGH around the tenth week of lactation of the spring calving dairy cow

An investigation into the factors associated with ewe colostrum production

peer-reviewedThe majority of lamb mortality which occurs during the first 24 h post-partum is preventable through providing the lamb with sufficient quantities of high quality colostrum during this time. Data from seven late gestation nutrition experiments carried out at this institute between 2002 and 2014 were collated into a single data set comprising of 415 twin bearing ewes. Analysis was carried out to investigate the key drivers of ewe colostrum production excluding nutrient intake, namely body reserve mobilisation, ewe breed type, ewe age, gestation length and lamb birth weight. The volume of colostrum produced at 1 and 18 h post-partum was significantly lower than the volume recorded at 10 h post-partum (P = 0.01). Multivariate regression analysis indicated that colostrum volume during the first 18 h post-partum was influenced by lamb birth weight (P = 0.01), ewe age (P = 0.01), breed type (P = 0. 01) and gestation length (P = 0.06). Live weight change (P = 0.05) also had a significant influence on the volume of colostrum produced but BCS change did not affect colostrum production (P = 0.25). Further multivariate regression analysis indicated that IgG yield was influenced ewe breed type (P = 0.01), lamb birth weight (P = 0.02), gestation length (P = 0.05) and BCS change (P = 0.04). Live weight change (P = 0.12) and ewe age (P = 0.62) did not influence the quantity of IgG produced. Leicester ewes produced less colostrum per kg lamb birth weight at 1 h post-partum compared to all other ewe breed types (P = 0.01) and less than Suffolk ewes at 10 h post-partum (P = 0.01). The result of this analysis shows the key factors excluding ewe nutrition that drive colostrum production. Ewe breed type in particular appears to play an important role in the ability of the ewe to produce sufficient quantities of adequate quality colostrum. In conclusion the result of this analysis highlights the important factors associated with ewe colostrum volume and IgG yield excluding nutrition. In particular the overall structure of the flock such as breed type and ewe age is important when considering the ability of the flock to meet colostrum demands and hence reduce lamb mortality

Do Different Breeds of Dairy Cow Differ in Their Ability to Digest Perennial Ryegrass?

Grazed grass is the cheapest feed source available for ruminant production systems in temperate climates (Finnernan et al. 2010) accounting for 70% and 90% of the diet of dairy cows in Ireland and New Zealand, respectively. Successful operation of grass-based dairy systems is based on achieving large intakes of high quality grass and efficiently converting it into high value milk solids (Prendiville et al. 2010). Prendiville et al. (2009) identified production efficiency differences between Holstein Friesian (HF) and Jersey (J) cows. They found that J had higher milk solids output per 100 kg bodyweight than HF. The aim of this study was to identify if HF, J and crossbred (J×HF) cows differ in their ability to digest perennial ryegrass

The Variation in Morphological Fractions of Perennial Ryegrass Cultivars throughout the Grazing Season and Subsequent Impacts on Organic Matter Digestibility

The grass plant is comprised of leaf blades, leaf sheath (pseudostem), true stem and dead material each differing in digestibility and their relative proportions can impact significantly on sward quality. The objective of this study was to determine the change in the proportion and organic matter digestibility (OMD) of leaf, pseudostem, true stem and dead fractions of four perennial ryegrass cultivars throughout a grazing season