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A desire for more sustainable pasture-based ruminant feeding systems has led to growing interest in utilising botanically-diverse pastures (BDP) over monoculture pastures. Research suggests that, from a human consumption viewpoint, grass-based ruminant feeding leads to more nutritionally desirable fatty acid (FA) and antioxidant concentrations in meat compared with concentrate feeding, which can affect meat quality. The FA, antioxidant and secondary metabolite content of plants differ, depending on species, maturity and seasonality, offering the potential through targeted feeding of BDP to produce meat with superior nutritional and antioxidant profiles. This review explores the effect, if any, that grazing ruminants on BDP has on the FA profile, fat-soluble vitamin, and antioxidant content of meat. The input-output relationship between forage and red meat constituents is complex and is likely affected by species diversity, forage consumption patterns and modulation of rumen fermentation processes. Further investigation is required to fully understand the effect that BDP may have on the composition and quality of ruminant meat.

Breeding values for feed intake and feed efficiency in beef cattle are generally derived indoors on high-concentrate (HC) diets. Within temperate regions of north-western Europe, however, the majority of a growing beef animal's lifetime dietary intake comes from grazed grass and grass silage. Using 97 growing beef cattle, the objective of the current study was to assess the repeatability of both feed intake and feed efficiency across 3 successive dietary test periods comprising grass silage plus concentrates (S+C), grazed grass (GRZ) and a HC diet. Individual DM intake (DMI), DMI/kg BW and feed efficiency-related parameters, residual feed intake (RFI) and gain to feed ratio (G : F) were assessed. There was a significant correlation for DMI between the S+C and GRZ periods (r = 0.32; P < 0.01) as well as between the S+C and HC periods (r = 0.41; P < 0.001), whereas there was no association for DMI between the GRZ and HC periods. There was a significant correlation for DMI/kg BW between the S+C and GRZ periods (r = 0.33; P < 0.01) and between the S+C and HC periods (r = 0.40; P < 0.001), but there was no association for the trait between the GRZ and HC periods. There was a significant correlation for RFI between the S+C and GRZ periods (r = 0.25; P < 0.05) as well as between S+C and HC periods (r = 0.25; P < 0.05), whereas there was no association for RFI between the GRZ and HC periods. Gain to feed ratio was not correlated between any of the test periods. A secondary aspect of the study demonstrated that traits recorded in the GRZ period relating to grazing bite rate, the number of daily grazing bouts and ruminating bouts were associated with DMI (r = 0.28 to 0.42; P < 0.05 - 0.001), DMI/kg BW (r = 0.36 to 0.45; P < 0.01 - 0.001) and RFI (r = 0.31 to 0.42; P < 0.05 - 0.001). Additionally, the number of ruminating boli produced per day and per ruminating bout were associated with G : F (r = 0.28 and 0.26, respectively; P < 0.05). Results from this study demonstrate that evaluating animals for both feed intake and feed efficiency indoors on HC diets may not reflect their phenotypic performance when consuming conserved forage-based diets indoors or when grazing pasture.

The aim of this study was to investigate the impact of ewe genetic merit on ewe performance and efficiency parameters. The study consisted of three genetic merit groups (New Zealand [NZ], High Irish, and Low Irish) and ran from 2016 to 2019, inclusive. Each genetic merit group contained 30 purebred Suffolk and 30 purebred Texel ewes, which were selected based on their maternal genetic indexes in their country of origin, namely Ireland (€uro-star Replacement index) or New Zealand (New Zealand Maternal worth). Ewe body condition score (BCS), ewe body weight (BW), milk yield, milk composition, dry matter intake (DMI), and efficiency parameters were all analyzed using linear mixed models. Ewe BW was similar across all genetic merit groups at each time point (P > 0.05). In comparison to both High and Low Irish ewes, NZ ewes had a higher BCS at mating, mid-pregnancy, lambing, week 10 post-lambing (PL, P < 0.05). Ewe BW change was similar across genetic merit groups, except between mating and mid-pregnancy where ewe BW loss was greater for NZ ewes than Irish ewes (P < 0.05) and between weeks 6 PL and 10 PL, where NZ ewes gained BW and High and Low Irish ewes lost BW (P < 0.01). Ewe milk yield, milk fat, total solids, and gross energy content were superior for milk produced by NZ ewes at week 6 PL in comparison to milk produced by High Irish and Low Irish ewes (P < 0.01). NZ ewes produced a greater quantity of milk solids/kg of BW at week 6 PL compared with High Irish ewes (P < 0.01), whereas Low Irish ewes did not differ from either NZ or High Irish (P > 0.05). Low Irish ewes had a greater daily DMI than High Irish ewes in late lactation (week 10 PL, P < 0.05) and had a greater DMI/kg of ewe BW compared with the High Irish ewes at the same time point (P < 0.05). NZ ewes weaned a litter BW equivalent to 60.4% of their mating BW, which was more than the Low Irish ewes who weaned 57.1% of the ewe’s BW at mating (P < 0.01), whereas the High Irish ewes did not differ from either the NZ or Low Irish ewes at 59.3% of the ewe’s BW at mating (P > 0.05). This study presents a range of parameters across ewes of high and low genetic merit, demonstrating the ability to achieve gains through selection of animals of high genetic merit. Sheep producers should consider genetic indexes as a tool to assist in the decision-making process of selecting replacement ewes and/or breeding rams, once satisfied the animal is correct, and meeting the breeding objectives of the system.

Portable accumulation chambers (PAC) enable gaseous emissions from small ruminants to be measured over a 50 min period, to date however, the repeatability of consecutive days of measurement in the PAC has not been investigated. The objectives of this study were to investigate: 1) the repeatability of consecutive days of gaseous measurements in the PAC, 2) the number of days required to achieve precise gaseous measurements, and 3) to develop a prediction equation for gaseous emissions in sheep. A total of 48 ewe lambs (c. 10 to 11 mo of age) were randomly divided into four measurement groups each day, for 17 consecutive days. Gaseous measurements were conducted between 0800 h and 1200 h daily. Animals were removed from perennial ryegrass silage for at least 1 h before measurements in the PAC and animals were assigned randomly to each of the 12 chambers. Methane (CH4; ppm) concentration, oxygen (O2; percentage) and carbon dioxide (CO2; percentage) were measured at 3 time points (0, 25, and 50 min after entry of the first animal into the first chamber). To quantify the effect of animal and day variation on gaseous emissions, between-animal, between-day and error variances were calculated for each gaseous measurement using a linear mixed model. The number of days required to gain a certain precision (defined as the 95% confidence interval (CI) range) for each gaseous measurement was also calculated. For all 3 gases the between-day variance (39% to 40%) accounted for a larger proportion of total variance compared to between-animal variance, while the repeatability of 17 consecutive days of measurement was 0.36, 0.31 and 0.23 for CH4, CO2 and O2, respectively. Correlations between consecutive days of measurement were strong for all 3 gases; the strongest correlation between d 1 and the remaining days for CH4, CO2 and O2 was 0.71 (d 1 and d 6), 0.77 (d 1 and d 2) and 0.83 (d 1 and d 5), respectively. A high level of precision was achieved when gaseous measurements from PAC were taken over 3 consecutive days. The prediction equation over-estimated gaseous production for all 3 gases: the correlations between actual and predicted gaseous output ranged from 0.67 to 0.71, with the r 2 ranging from 0.45 to 0.71. Results from this study will aid the refinement of the protocol for the measurement of gaseous emissions in sheep using the PAC.

International audience; Sheep are often used as a proxy for dairy cows when measuring the digestibility of a feed. In recent years grassland management guidelines for ruminant animals have been re-evaluated in accordance with the progression in animal genetics and the acknowledgement that genetic potential has an influence on both feed intake and digestibility. Recommended pre-grazing herbage mass (HM) targets are now much lower with improved perennial ryegrass varieties available for grazing swards. The objective of this study was to compare the in vivo digestibility of perennial ryegrass in wether sheep and lactating dairy cows. The experimental design was selected to measure the effect of animal species (cows, sheep), sward HM measured cutting herbage at 4 cm above ground level (low: 1 700 kg DM/ha and high: 4 000 kg DM/ha) and season (Spring: Apr-May, Summer: Jul-Aug) on the digestibility of perennial ryegrass. Each HM treatment was offered to each animal within species and season for 12 d using a 2 HM x 2 period changeover Latin square design. There were eight cows and eight sheep, so there were four 2 x 2 Latin squares for each animal species (two) at each season (two), giving 64 observations. During each 12 d experimental period, the first 6 d were used for adaptation (adaptation phase) and the final 6 d were used for measurement (measurement phase). In vivo organic matter digestibility (OMD) in spring did not differ between animal species but in summer sheep had higher in vivo OMD than cows. The results described herein highlight the suitability of wether sheep as an alternative to dairy cows for determining the digestibility of perennial ryegrass in spring but not in summer. Stage of growth of the plant, which is intrinsically linked to season, should be considered as results show that digestibility in the ruminant was affected by season but not differentially affected by changing sward HM. (C) 2021 The Authors. Published by Elsevier B.V. on behalf of The Animal Consortium.

The objective of this study was to develop and validate models to predict dry matter intake (DMI) of grazing dairy cows using animal energy sinks and status traits in combination with traits related to grazing behaviour, body measurements, thermal imaging, heart rate and blood pressure. The dataset used to develop the models comprised 33 measurements from 113 Holstein-Friesian dairy cows. Multivariable regression models were constructed incorporating each independent variable into a benchmark model incorporating the energy sinks (milk yield [MY], fat %, protein % and body weight [BW]) and status traits (feeding treatment, parity and calving day of year). Of the 33 variables tested, 10 showed an association with DMI (P < 0.25). These variables were incorporated into a backward linear regression model. Variables were retained in this model if P < 0.05. Grazing bout duration and rumination mastication rate were retained in the final model. The inclusion of these variables in the model increased DMI prediction by 0.01 (coefficient of determination [R 2] = 0.85) compared to the benchmark model alone (R 2 = 0.84). The models were applied to data recorded on an independent herd of 51 dairy cows. The R 2 upon validation was 0.80 for the benchmark model and 0.79 for the model incorporating rumination mastication rate and grazing bout duration in combination with the benchmark variables. The separation of grazing bout duration and rumination mastication rate to predict DMI revealed rumination mastication rate slightly increases predictive accuracy upon external validation (R 2 = 0.81), whereas grazing bout duration did not (R 2 = 0.78). This suggests that grazing bout duration is not a robust trait for DMI prediction. Results from this study suggest that rumination mastication rate can slightly increase the accuracy of DMI prediction surpassing known energy sinks and status traits.

Portable accumulation chambers (PAC) enable short-term spot measurements of gaseous emissions including methane (CH4), carbon dioxide (CO2), and oxygen (O2) consumption from small ruminants. To date the differences in morning and evening gaseous measurements in the PAC have not been investigated. The objectives of this study were to investigate: 1) the optimal measurement time in the PAC, 2) the appropriate method of accounting for the animal’s size when calculating the animal’s gaseous output, and 3) the intra-day variability of gaseous measurements. A total of 12 ewe lambs (c. 10 to 11 months of age) were randomly selected each day from a cohort of 48 animals over nine consecutive days. Methane emissions from the 12 lambs were measured in 12 PAC during two measurement runs daily, AM (8 to 10 h) and PM (14 to 16 h). Animals were removed from Perennial ryegrass silage for at least 1 h prior to measurements in the PAC and animals were assigned randomly to each of the 12 chambers. Methane (ppm) concentration, O2 and CO2 percentage were measured at 5 time points (T1 = 0.0 min, T2 = 12.5 min, T3 = 25.0 min, T4 = 37.5 min, and T5 = 50.0 min from entry of the first animal into the first chamber) using an Eagle 2 monitor. The correlation between time points T5-T1 (i.e., 50 min minus 0 min after entry of the animal to the chamber) and T4-T1 was 0.95, 0.92, and 0.77 for CH4, O2, and CO2, respectively (P < 0.01). The correlation between CH4 and CO2 output and O2 consumption, calculated with live-weight and with body volume was 0.99 (P < 0.001). The correlation between the PAC measurement recorded on the same animal in the AM and PM measurement runs was 0.73. Factors associated with CH4 production included: day and time of measurement, the live-weight of the animal and the hourly relative humidity. Results from this study suggest that the optimal time for measuring an animal’s gaseous output in the PAC is 50 min, that live-weight should be used in the calculation of gaseous output from an animal and that the measurement of an animal’s gaseous emissions in either the AM or PM does not impact on the ranking of animals when gaseous emissions are measured using the feeding and measurement protocol outlined in the present study.

The objective of this study was to compare mid-infrared reflectance spectroscopy (MIRS) analysis of milk and near-infrared reflectance spectroscopy (NIRS) analysis of feces with regard to their ability to predict the dry matter intake (DMI) of lactating grazing dairy cows. A data set comprising 1,074 records of DMI from 457 cows was available for analysis. Linear regression and partial least squares regression were used to develop the equations using the following variables: (1) milk yield (MY), fat percentage, protein percentage, body weight (BW), stage of lactation (SOL), and parity (benchmark equation); (2) MIRS wavelengths; (3) MIRS wavelengths, MY, fat percentage, protein percentage, BW, SOL, and parity; (4) NIRS wavelengths; (5) NIRS wavelengths, MY, fat percentage, protein percentage, BW, SOL, and parity; (6) MIRS and NIRS wavelengths; and (7) MIRS wavelengths, NIRS wavelengths, MY, fat percentage, protein percentage, BW, SOL, and parity. The equations were validated both within herd using animals from similar experiments and across herds using animals from independent experiments. The accuracy of equations was greater for within-herd validation compared with across-herds validation. Across-herds validation was deemed the more suitable method to assess equations for robustness and real-world application. The benchmark equation was more accurate [coefficient of determination (R2) = 0.60; root mean squared error (RMSE) = 1.68 kg] than MIRS alone (R2 = 0.30; RMSE = 2.23 kg) or NIRS alone (R2 = 0.16; RMSE = 2.43 kg). The combination of the benchmark equation with MIRS (R2 = 0.64; RMSE = 1.59 kg) resulted in slightly superior fitting statistics compared with the benchmark equation alone. The combination of the benchmark equation with NIRS (R2 = 0.58; RMSE = 1.71 kg) did not result in a more accurate prediction equation than the benchmark equation. The combination of MIRS and NIRS wavelengths resulted in superior fitting statistics compared with either method alone (R2 = 0.36; RMSE = 2.15 kg). The combination of the benchmark equation and MIRS and NIRS wavelengths resulted in the most accurate equation (R2 = 0.68; RMSE = 1.52 kg). A further analysis demonstrated that Holstein-Friesian cows could predict the DMI of Jersey × Holstein-Friesian crossbred cows using both MIRS and NIRS. Similarly, the Jersey × Holstein-Friesian animals could predict the DMI of Holstein-Friesian cows using both MIRS and NIRS. The equations developed in this study have the capacity to predict DMI of grazing dairy cows. From a practicality perspective, MIRS in combination with variables in the benchmark equation is the most suitable equation because MIRS is currently used on all milk-recorded milk samples from dairy cows.

The 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.

A two-year (2015 and 2016) grazing study was established to compare ewe and lamb performance when grazed on a perennial ryegrass only sward compared to more diverse sward types. In that study four sward types were investigated: a perennial ryegrass (Lolium perenne) only sward receiving 163 kg nitrogen per hectare per year (N/ha/yr) (PRG); a perennial ryegrass and white clover (Trifolium repens) sward receiving 90 kg N/ha/yr (PRGWC); a six species sward (two grasses (perennial ryegrass and timothy (Phleum pratense)), two legumes (white and red clover (Trifolium pratense)) and two herbs (ribwort plantain (Plantago lanceolata) and chicory (Cichorium intybus)) receiving 90 kg N/ha/yr (6S); and a nine species sward containing cocksfoot (Dactylis glomerata), greater birdsfoot trefoil (Lotus pedunculatus) and yarrow (Achillea millefolium) in addition to the six species listed above, receiving 90 kg N/ha/yr (9S). Each sward type was managed as a separate farmlet and stocked with 30 twin-rearing ewes at a stocking rate of 12.5 ewes/ha under rotational grazing management from turnout post-lambing until housing. Lamb live weight was recorded fortnightly and lambs were drafted for slaughter at 45 kg. Ewe live weight and body condition score (BCS) were recorded on five occasions annually. Lamb faecal egg count (FEC) was recorded fortnightly and lambs were treated with anthelmintics when mean lamb FEC per sward type was above 400 eggs per gram. Ewes grazing the 6S and 9S swards had heavier (Plt; 0.01) live weights and BCS throughout the study than the ewes grazing the PRG sward. Lambs grazing the 6S sward were heavier than lambs grazing all other sward types of 14 weeks old (Plt; 0.05). Lambs grazing the PRG sward required more days to reach slaughter weight than lambs grazing all other sward types (Plt; 0.001). Lambs grazing the 6S and 9S swards required fewer anthelmintic treatments than lambs grazing the PRG or PRGWC swards. In conclusion, grazing multispecies swards improved ewe and lamb performance and reduced the requirement for chemical anthelmintics.

Nitrogen (N) use efficiency in beef cattle is low (10–20%), resulting in large amounts of N excreted into the environment. The objective of this study was to evaluate the effects of chitosan inclusion and dietary crude protein (CP) level on nutrient intake and digestibility, ruminal fermentation, and N excretion in beef heifers. Eight Belgian Blue × Holstein Friesian cross beef heifers (752 ± 52 kg BW) were used in a 4 × 4 Latin square with a 2 × 2 factorial design. Factors were dietary CP concentration—high CP, 16% (HP) or low CP, 12% (LP)—and chitosan inclusion—0 or 10 g kg−1 dry matter (DM) offered at 50:50 forage concentrate ratio on a dry matter (DM) basis. Apparent total tract digestibility of DM, organic matter (OM), and CP were reduced (p &lt, 0.001) with chitosan inclusion, whereas offering the HP diets increased apparent total tract digestibility of CP (p &lt, 0.001). Offering the HP diets increased urinary N excretion (p &lt, 0.001), while chitosan inclusion increased N excretion in faeces (p &lt, 0.05). Ruminal pH was increased with chitosan inclusion (p &lt, 0.01). There was a CP × chitosan interaction for rumen ammonia (NH3) concentrations (p &lt, 0.05). Including chitosan in the HP diets increased ruminal NH3 concentration while having no effect on the LP diets. Urinary N excretion was increased with increased levels of CP, but chitosan inclusion increased the quantity of N excreted in the faeces.

International audience; It is essential to have accurate data relating sward herbage mass (HM) to voluntary dry matter intake (VDMI) and in vivo organic matter digestibility (OMDIV) across the year. This will ensure that the production performance of animals grazing differing HM swards can be accurately predicted using in vitro and in situ methods. The objectives of this experiment were to (i) determine the OMDIV and VDMI of sheep offered perennial ryegrass differing in HM throughout the growing season and (ii) evaluate in vitro gas production (IVGP) and in situ indigestible neutral detergent fibre (iNDFIS) as methods of predicting OMDIV. A 3 × 3 Latin square design was used to investigate three HM treatments. The target HM (measured > 4 cm) of perennial ryegrass for the three HM treatments was 1200 kg dry matter (DM)/ha (Low), 2500 kg DM/ha (Medium) and 4000 kg DM/ha (High). The experiment was a Latin square design repeated in three time stages (TS) in 2013 (TS1, TS2 and TS3). A 3 × 2 incomplete Latin square design was used in early spring 2014 (TS4). In TS4 the HM were lower than in the previous TS at 1000 kg DM/ha (Low), 1800 kg DM/ha (Medium) and 2500 kg DM/ha (High). Each experimental period within each TS consisted of a 6 day adaptation phase and 6 day measurement phase; with 12 Texel wether sheep used. Sheep were fed ad libitum to ensure a 10% refusal rate. The interaction between TS and HM treatment had the greatest effect on chemical composition, VDMI and OMDIV. Low HM swards had the greatest VDMI and OMDIV. For each 1000 kg DM/ha increase in HM, OMDIV was reduced by 2.3% on average. This varied from 0.9% in TS4 to 2.7% in TS3. There was no difference between HM treatments in the rate of digestion of digestible NDF using the IVGP technique. In situ indigestible NDF concentration and OMD derived from IVGP (OMDGP) were highly correlated with OMDIV (r2 = 0.901 and 0.895 respectively) and moderately correlated with digestible organic matter intake (DOMI) (r2 = 0.633 and 0.652 respectively). It can be concluded that the interaction between HM and TS will greatly affect OMDIV and VDMI. Secondly OMDIV can be predicted by both iNDFIS and OMDGP with acceptable accuracy to allow for their use in future feed evaluations.

The objective of this study was to investigate the impact of the ewe’s maternal genetic merit and country of origin (New Zealand or Ireland) on ewe reproductive, lambing and productivity traits. The study was performed over a four year period (2016 to 2019) and consisted of three genetic groups: high maternal genetic merit New Zealand (NZ), high maternal genetic merit Irish (High Irish) and low maternal genetic merit Irish (Low Irish) ewes. Each group contained 30 Suffolk and 30 Texel ewes, selected based on the respective national maternal genetic indexes; i.e. either the New Zealand Maternal Worth (New Zealand group) or the €uro-star Replacement index (Irish groups). The impact of maternal genetic merit on reproductive traits such as litter size; lambing traits such as gestation length, birth weight, lambing difficulty, mothering ability, and productivity traits such as the number of lambs born and weaned were analyzed using linear mixed models. For binary traits, the impact of maternal genetic merit on reproductive traits such as conception to first AI service; lambing traits such as dystocia, perinatal lamb mortality and productivity traits such as ewe survival were analyzed using logistic regression. New Zealand ewes outperformed Low Irish ewes for conception to first AI (P0.05). Lambs born from NZ ewes were 4.67 (95% CI: 1.89 to 11.55; P

Simple Summary Reducing methane emissions from dairy cows is environmentally important. In this experiment, pasture fed dairy cows offered concentrates containing linseed oil emitted 18% less methane per kg of milk solids produced than those offered concentrates containing either stearic acid or soy oil. Additionally, cows fed linseed oil or soy oil produced more milk than those fed stearic acid. These results may contribute to the development of strategies to reduce methane emissions from pasture-based livestock whilst maintaining or improving animal productivity. Abstract Emissions of methane (CH4) from dairy production systems are environmentally detrimental and represent an energy cost to the cow. This study evaluated the effect of varying C18 fatty acid sources on CH4 emissions, milk production and rumen methanogen populations in grazing lactating dairy cows. Forty-five Holstein Friesian cows were randomly allocated to one of three treatments (n = 15). Cows were offered 15 kg dry matter (DM)/d of grazed pasture plus supplementary concentrates (4 kg DM/d) containing either stearic acid (SA), linseed oil (LO), or soy oil (SO). Cows offered LO and SO had lower pasture DM intake (DMI) than those offered SA (11.3, 11.5 vs. 12.6 kg/d). Cows offered LO and SO had higher milk yield (21.0, 21.3 vs. 19.7 kg/d) and milk protein yield (0.74, 0.73 vs. 0.67 kg/d) than those offered SA. Emissions of CH4 (245 vs. 293, 289 g/d, 12.4 vs. 15.7, 14.8 g/kg of milk and 165 vs. 207, 195 g/kg of milk solids) were lower for cows offered LO than those offered SA or SO. Methanobrevibacter ruminantium abundance was reduced in cows offered LO compared to SA. Offering supplementary concentrates containing LO can reduce enteric CH4 emissions from pasture fed dairy cows.

Greenhouse gas (GHG) emissions and nitrogen (N) efficiencies were modeled for 2 genetic groups (GG) of Holstein-Friesian cows across 3 contrasting feeding treatments (FT). The 2 GG were (1) high economic breeding index (EBI) animals representative of the top 5% of cows nationally (elite) and (2) EBI representative of the national average (NA). The FT represented (1) generous feeding of pasture, (2) a slight restriction in pasture allowance, and (3) a high-concentrate feeding system with adequate pasture allowance. Greenhouse gas and N balance models were parameterized using outputs generated from the Moorepark Dairy Systems model, a stochastic budgetary simulation model, having integrated biological data pertaining to the 6 scenarios (2 GG × 3 FT) obtained from a 4-yr experiment conducted between 2013 and 2016. On a per hectare basis, total system GHG emissions were similar for both elite and NA across the 3 FT. Per unit of product, however, the elite group had 10% and 11% lower GHG emissions per kilogram of fat- and protein-corrected milk and per kilogram of milk solids (MSO; fat + protein kg), respectively, compared with the NA across the 3 FT. The FT incorporating high concentrate supplementation had greater absolute GHG emissions per hectare as well as GHG per kilogram of fat- and protein-corrected milk and MSO. The elite group had a slightly superior N use efficiency (N output/N input) and lower N surplus (N input – N output) compared with the NA group. The high concentrate FT had an inferior N use efficiency and a higher N surplus. The results of the current study demonstrate that breeding for increased EBI will lead to a general improvement in GHG emissions per unit of product as well as improved N efficiency. The results also illustrate that reducing concentrate supplementation will reduce GHG emissions, GHG emissions intensity, while improving N efficiency in the context of pasture-based dairy production.

Provision of adequate nutrient intake in late gestation of the ewe is an important determinant of dam and offspring performance. A 2 &times, 3 factorial design experiment examining two forage types, whole crop wheat silage (WCWS) or grass silage (GS) offered to one of three prolific breed types, (Belclare X, Lleyn X, Mule (Bluefaced Leicester &times, Blackface Mountain)), was conducted. Forage type had no impact on dry matter (DM) or metabolizable energy (ME) intake, body weight and body condition score change, or colostrum production (p &gt, 0.05). Ewes offered WCWS had lower crude protein (CP) intake (p &lt, 0.0001) and a lower combined litter weight (p &lt, 0.05). Mule ewes consumed less DM, CP, (p &lt, 0.05), and ME (p &lt, 0.01) compared to Belclare X and Lleyn X ewes however, water intake per kg DM consumed did not differ with breed type (p &gt, 0.05). Colostrum yield over the first 18 h postpartum was lower for Mule ewes compared to other breed types (p &lt, 0.05). In conclusion, results from this study suggest nutrient concentration and balance as opposed to forage type is important for late gestation nutrition and breed type can impact feed intake and colostrum yield.

Plant based by-products (BP) produced from food and bioethanol industries are human inedible, but can be recycled into the global food chain by ruminant livestock. However, limited data is available on the methanogenesis potential associated with supplementing a solely BP formulated concentrate to a pastoral based diet. Therefore the objective of this in vitro study was to investigate the effects of BP inclusion rate (in a formulated concentrate) to a pasture based diet on dietary digestibility, rumen fermentation patterns, methane production and the prokaryotic microbial community composition. Diets consisted of perennial ryegrass and one of two supplementary concentrates, formulated to be isonitrogenous (16% CP) and isoenergetic (12.0 MJ/ME/kg), containing either 35% BP, barley and soybean meal (BP35) or 95% BP (BP95) offered on a 50:50 basis, however, starch, NDF and fat content varied. The BPs, included in equal proportions on a DM basis, were soyhulls, palm kernel expeller and maize dried distillers grains. The BP35 diet had greater (P < 0.05) digestibility of the chemical constituents DM, OM, CP, NDF, ADF. Greater total VFA production was seen in the BP35 diet (P < 0.05). Daily methane production (mmol/day; +22.7%) and methane output per unit of total organic matter digested (MPOMD; +20.8%) were greatest in the BP35 diet (P < 0.01). Dietary treatment influenced microbial composition (PERMANOVA; P = 0.023) with a greater relative abundance of Firmicutes (adj P < 0.01) observed in the BP35. The Firmicutes:Bacteroidetes ratio was significantly reduced in the BP95 diet (P < 0.01). The relative proportions of Proteobacteria (adj P < 0.01), Succinivibrionaceae (adj P < 0.03) and Succinivibrio (adj P = 0.053) increased in the BP95 diet. The abundance of Proteobacteria was found to be negatively associated with daily methane production (rs, −0.71; P < 0.01) and MPOMD (rs, −0.65; P < 0.01). Within Proteobacteria, the relationship of methane production was maintained with the mean abundance of Succinivibrio (rs, −0.69; P < 0.01). The abundance of the Firmicutes phyla was found to be positively correlated with both daily methane production (rs, 0.79; P < 0.001) and MPOMD (rs, 0.75; P < 0.01). Based on in vitro rumen simulation data, supplementation of an exclusively BP formulated concentrate was shown to reduce daily methane output by promoting a favorable alteration to the rumen prokaryotic community.

Two tetraploid varieties, Astonenergy and Delphin, and two diploid varieties of perennial ryegrass (Lolium perenne), Tyrella and Glenroyal, were evaluated for voluntary dry matter intake (VDMI) and in vivo organic matter digestibility (OMD) using Texel wether sheep housed in digestibility stalls. The structural profile and leaf, stem, dead proportions of the sward were also measured. The experiment was repeated on three occasions (Time Stage (TS)): May/June 2013 (TS1), August/September 2013 (TS2) and September/October 2014 (TS3). Data from both years were analysed separately. There was no variety effect on VDMI during TS1 (1481 ± 44.4 g/day), TS2 (1621 ± 41.7 g/day) or TS3 (1223 ± 86 g/day). There was a significant interaction between TS and variety for OMD (P

Context Pasture allowance (PA) in early lactation is widely acknowledged to influence animal performance; however, climatic factors can limit grass growth in early spring, resulting in potential feed deficits on farm. Aim The present study determined whether PA restrictions imposed in early lactation impair energy balance and metabolic health of the cow. Methods One hundred and five cows were assigned to one of seven grazing treatments from 14 March to 4 July 2016 (16 weeks). The control-treatment cows were offered a PA to achieve a post-grazing sward height of 3.5 cm. The cows on the remaining treatments were offered a PA representing 60% of that offered to the control cows for a duration of 2 or 6 weeks from 14 March (mid-March; MMx2 and MMx6), 28 March (end-March; EMx2 and EMx6) or 11 April (mid-April; MAx2 and MAx6). Measurements were collected over the final 2-week period of the restriction for each individual restricted treatment and the control treatment. Key results Restricting PA in early lactation (34–88 days in milk) resulted in a mean reduction in dry-matter intake (DMI) of 25%; however, DMI as a proportion of the control treatment declined for EMx6 (75% of control DMI achieved) and MAx6 (65%) compared with the MMx6 (78%), which may be attributable to changes in the sward, as the plant changes from the vegetative to reproductive phase during this period. The reduction in milk production, relative to the control treatment, was similar among all restricted treatments (18%), resulting in a 1.1-kg reduction in milk output per 1-kg reduction in DMI. However, there was no effect of PA restriction or duration on body condition score, energy balance or blood metabolites, suggesting that the animals used in the current study made sufficient physiological adaptions to partition energy for the maintenance of body reserves. Conclusion In conclusion, short-term restrictions of PA up to 25% of DMI, for up to 6 weeks, can be used as a management strategy to cope with feed deficits in early lactation without impairing normal metabolic function of the early lactation dairy cow. Implications The results of the present study identified the ability of the early lactation dairy cow at grass to adapt to short-term deficits in pasture availability, without affecting the metabolic functioning of the animals

The importance of increased grass availability in the diet of the early lactation dairy cow in spring-calving pasture-based systems is widely reported. To combat the effect of low over winter growth rates, closing swards earlier in autumn can allow for greater accumulation of herbage for grazing in spring. The aim of this study was to identify the impact of three autumn closing treatments (varying closing rotation dates); (1) Early – September 25th to November 9th, (2) Normal – October 10th to November 24th and (3) Late – October 25th to December 9th, on late lactation milk production and early lactation milk production in the subsequent spring. The goal was to identify the optimum recommendations for autumn closing management to achieve increased milk production in spring resulting from increased grass availability, without compromising on animal performance in late lactation. There was no effect of autumn closing treatment on late lactation milk yield or milk solids yield. There was, however, a decline in milk protein concentration, associated with the diet change at housing of the early closed treatment (−1.6 g/kg milk) and normal treatment (−0.7 g/kg milk) in autumn compared with the late closed treatment (41.5 g/kg milk), as a result of the increased silage fed during this period (473.2, 345.8 and 163.8 kg DM/cow, respectively). Each one day increase in closing resulted in an extra 16 kg DM/ha in pre-grazing herbage mass on February 1st of the subsequent year (R2 = =0.502). The resulting increases in pre-grazing herbage mass contributed to increased daily herbage allowance (DHA; +2.9 kg DM/cow) and total dry matter intake (+1.3 kg DM/cow) for the early treatment in spring compared with the normal and late closed treatment. Each 1 kg increase in DHA resulted in an increase of 0.38 kg milk/cow/day. A greater proportion of silage was required cumulatively on the early closed treatment (628 kg DM/cow) in contrast to the late closed treatment (419 kg DM/cow) between the autumn and spring period. However, the increased milk production associated with the increased grass availability in spring outweighed the cost associated with the increased silage requirement. Closing the farm early in autumn offers significant advantages in terms of higher DHA, increased dry matter intake and higher milk yields the following spring. Therefore, it is recommended the closing rotation should begin in late September and cease by mid-November, where there is a high demand for grass in early spring.

Number of lambs born is a key factor influencing profitability of seasonal sheep meat production systems and a key driver of nutrient requirements. Energy and nutrient requirements to support foetal development, mammogenesis and lactogensis increase in the final eight weeks of ovine gestation. A 3 × 2 factorial design experiment involving 90 twin bearing ewes was conducted during the final eight weeks of pregnancy with ewes offered 100% of predicted metabolisable energy (ME) requirements. Three prolific breed types (Mule (Bluefaced Leicester X Blackface mountain), Belclare X and Lleyn X) were offered one of two silage types (grass (GS) or whole crop wheat (WCW)) resulting in six treatments (n = 15). Where silage intake was insufficient to meet 100% of ME requirements, concentrates were offered to reach 100% of ME allocation per ewe per day. Colostrum yield at one, ten and eighteen hours, combined litter weight (CLW), maternal body weight and body condition score (BCS) change during the final eight weeks of gestation were recorded. The data were analysed using repeated measures and glimmix in SAS (Version 9.4). Ewes offered grass silage produced lambs with a higher CLW (P = 0.03). There was an interaction between breed type and silage type with Mule ewes offered WCW producing a lower CLW than Mule ewes offered GS (P = 0.004), with no difference for Belclare or Lleyn ewes (P > 0.05). Within silage type Mule ewes offered GS had a higher CLW than Belclare ewes (P < 0.05) while within WCW Belclare ewes had a higher CLW than Lleyn ewes (P < 0.05). Other variables did not differ with treatment. In conclusion, a breed specific response was recorded in this study whereby Mule ewes produced a lower CLW when offered WCW compared to GS silage, though no differences were observed in the other breed types studied.

Multispecies swards (MSS) for ruminants are increasing in popularity in temperate regions. The objective of this study was to evaluate the effect of MSS containing grasses, legumes and herbs on lambs faecal egg counts (FEC) compared to a perennial ryegrass monoculture. Over two years (2015 and 2016) lambs (n = 60 per year, n = 120 in total per treatment) grazed one of four sward types. The treatments were: perennial ryegrass only (PRG), perennial grass and white clover (PRGWC), six species sward (perennial ryegrass, timothy, plantain, chicory, white and red clover; 6S) and nine species (9S) additional to the 6S were cocksfoot, greater birdsfoot trefoil and yarrow. Feces samples were collected fortnightly commencing when lambs were six weeks old and FEC were determined by the modified McMaster procedure for quantifying Nematodirus and Trichostrongylus eggs. All lambs were treated with anthelmintic at 12 weeks of age and subsequent anthelmintic treatments were administered when a threshold of 400 egg per gram (epg) was reached. The statistical analysis used was a repeated measures model in PROC MIXED of SAS. Nematodirus FEC did not differ with treatment (P > 0.05). Trichostrongylus FEC was influenced by sward type (P < 0.05), the lambs grazing the PRG sward displaying higher FEC, while the lambs grazing the 9S sward displaying lower FEC compared to other treatments. The lambs offered PRG required fewer days in reach the 400 epg threshold compared to the other treatments (P < 0.05) that did not differ. The repeatability of FEC from one date to the next date was 21.54% and 11.85% for Nematodirus and Trichostrongylus respectively, being considered low. The correlation between FEC (Nematodirus) and ADG (weaning-slaughter) was positive (0.1377), but FEC (Trichostrongylus) and ADG correlation was negative (-0.1084). These results suggest that lambs offered the 9S treatment had lower FEC of Trichostrongylus eggs compared to PRG.

SUMMARYA detailed survey was undertaken to assess the rate of production and current management practices on Irish sheep farms and quantify their associations with flock size and ewe breed type. A total of 39 questions relating to the farm production system and farm management practices were devised, including: producer age, location, farm size, livestock numbers and type, in addition to flock management data such as flock breeding policy, lamb finishing strategy, flock health, lambing date, winter housing and feeding practices. A total of 717 sheep producers were surveyed across 45 different discussion groups. The surveyed respondents were sub-divided into four groups depending on flock size (very small, small, medium and large) and into three groups depending on ewe breed type (maternal, terminal and hill). The average survey respondent was 48 years old, with a flock size of 150 breeding ewes on a farm size of 58 ha. The average stocking rates were 6·55 and 3·14 ewes/ha and weaning rates were 1·44 and 1·02 lambs per ewe joined to the ram for the lowland and hill flocks, respectively. Relative to very small flocks (190 ewes) had higher stocking rates (6·98v.5·66 ewes/ha) and ewe to ram ratios (40v.30), and tended to lamb later in the year. The rate of technology adoption such as faecal egg sampling and pregnancy scanning was greater on larger flocks compared with smaller flocks. Flocks with maternal ewe breeds had higher scanning and weaning rates, and drafted a greater proportion of lambs off grass compared with flocks with terminal and hill ewe breeds. Flocks with maternal and terminal ewe breed types were more likely to winter house ewes, lamb indoors, test silage quality and have a handling unit compared with flocks with hill-type ewe breeds. Results from the present study provide a bank of knowledge on current Irish sheep industry performance and show that flock size and ewe breed type have a significant impact on key flock performance variables.

The objective of this study was to investigate the impact of concentrate supplementation during early lactation on grass intake by the lactating ewe and subsequent ewe and lamb performance during the first seven wk post-partum. Fifty-four twin bearing and rearing ewes, were randomly allocated to one of three dietary treatments (n = 18) on d 7 (± two d) of lactation (experimental d zero). Dietary treatments were as follows; GO = zero-grazed grass ad libitum from d 7 to d 49 post-partum, GC = zero-grazed grass ad libitum plus 500 g fresh weight (FW) of concentrate supplementation from d 7 to d 49 post-partum, GC21 = zero-grazed grass ad libitum from d 7 to d 49 post-partum plus 500 g FW of concentrate supplementation from d 7 to d 21 post-partum. Each ewe was penned independently with her progeny on slatted flooring at 72 h post-partum with access to a straw bedded creep for lambs only. Zero-grazed grass was harvested from predominantly perennial ryegrass (Lolium perenne) swards daily at 0730 h and cut to a height of 3.5 cm. Grass DMI from wk two to seven of lactation was lower for GC ewes than GO (P 0.10) or total OMI (P > 0.10) with total OMI ranging from 1.81 to 1.94 kg per ewe per d. Rumen fluid pH dropped during the first seven d of the experiment for GC and GC21 ewes (P 0.10). The results of this study show that when ewes were offered zero-grazed grass during early lactation, concentrate feeding reduced grass DMI with no improvement in milk yield until wk 7 of lactation.

The objective of this study was to quantify the effects of ewe prolificacy potential (PP; predicted number of lambs born ewe yr), as dictated by sire breed type, and stocking rate (SR; ewes ha) on ewe production efficiency (kg lamb live weight weaned:kg ewe live weight mated), lamb growth, lamb carcass output, and dry matter (DM; kg) and energy (UFL; unit of energy kg DM) consumption (in the form of both grazed and conserved herbage, concentrate supplementation, and total) in a temperate grass-based lamb production system. The study was a 2 × 3 factorial design, consisting of 2 differing ewe prolificacy potentials (medium prolificacy [MP]-Suffolk-sired crossbred ewes and high prolificacy [HP]-Belclare-sired crossbred ewes) and 3 stocking rates: low (LSR; 10 ewes ha), medium (MSR; 12 ewes ha), and high (HSR: 14 ewes ha). Each treatment was managed in a 5-paddock rotational system for the duration of the study. The HP treatment weaned more lambs ewe and ha ( 0.05). Increasing stocking rate increased the number of lambs weaned ha ( < 0.001) and increased lifetime lamb ADG ha ( < 0.001). Lamb carcass output (kg) ha was highest at the HSR, intermediate at the MSR, and lowest at the LSR ( < 0.001). The quantity of DM and UFL consumed ewe and lamb unit and kg of lamb carcass produced ha increased as stocking rate increased ( < 0.001). In conclusion, results from this study demonstrate HP ewes to be more efficient in the production of lamb. Increasing stocking rate provides the opportunity to increase lamb carcass output ha; however, achieving this increase in output required additional DM and UFL ewe and lamb unit above 12 ewes ha.

The objective of this study was to investigate the effects of replacing barley and soybean meal with increasing levels of by-products on production, digestive, and metabolic parameters in early-mid lactation dairy cows offered perennial ryegrass-based pasture. Forty-eight (32 multiparous and 16 primiparous) dairy cows that were 64 ± 24 d in milk were assigned to 1 of 4 pasture-based dietary treatments (n = 12) in a randomized block design experiment that ran for 70 d. Treatments consisted of a perennial ryegrass-based pasture and 1 of 4 supplementary concentrates: BP35, BP55, BP75, and BP95 containing 35, 55, 75, and 95% by-products, respectively, in the concentrate on a dry matter basis. The by-products used were soyhulls, dried distillers grains, and palm kernel extract in equal proportions. Barley and soybean meal were replaced as by-product inclusion level increased. In this study, intakes of pasture dry matter (15.7 kg) and total dry matter (21.1 kg) were not affected by treatment. Similarly, milk production parameters (milk yield, milk composition, somatic cell count, and urea) were not different between treatments. Unsaturated fatty acids were lower in the milk of cows offered BP35 and BP55 compared with those offered BP75 and BP95. Concentrations of β-hydroxybutyrate, nonesterified fatty acids, and other blood metabolites were within normal range and did not differ between treatments, and cow body condition score and body weight were also not different. Equally, N was unaffected by diet. Blood urea N was lower in the BP75 group compared with BP35. This study demonstrated that barley and soybean meal can be replaced with soyhulls, dried distillers grains, and palm kernel extract without affecting milk production, digestive, or metabolic parameters in dairy cows offered a pasture-based diet.

The objective of the present study was to investigate the effect of ewe prolificacy potential (PP; predicted number of lambs born per ewe per year) as dictated by sire breed type, stocking rate (SR; ewes per ha), and their interaction on ewe and lamb performance in a temperate grass-based lamb production system. The study was a 2 × 3 factorial design, consisting of 2 differing ewe PP and 3 SR which included 180 medium prolificacy potential (MP- Suffolk-sired crossbred ewes) and 180 high prolificacy potential ewes (HP- Belclare-sired crossbred ewes) allocated to 1 of 3 ( = 60 ewes) SR: low (LSR; 10 ewes per ha), medium (MSR; 12 ewes per ha) or high (HSR: 14 ewes per ha). Each treatment was managed in a 5-paddock rotational grazing system for the duration of the study. Medium prolificacy ewes were consistently heavier ( < 0.001) compared to HP ewes, with HP ewes having a higher BCS at lambing and 6 wk post-lambing (PL; < 0.05). Low SR ewes had a higher BW ( < 0.05) and BCS ( < 0.05) at mating, 6 wk PL, and weaning relative to MSR and HSR ewes which did not differ from each other. Lambs born to MP ewes were heavier at birth and weaning ( < 0.001) and achieved a higher ADG from birth to weaning ( < 0.05). Ewe PP had no effect on lifetime ADG or d to slaughter (DTS) with HP lambs yielding a higher carcass weight ( < 0.001). Low SR and MSR lambs achieved higher ADG from birth to weaning ( < 0.001) and weaning weight ( < 0.001) relative to HSR lambs and did not differ from each other, while post-weaning and lifetime lamb ADG was highest at the LSR, intermediate at the MSR, and lowest at the HSR ( < 0.001). A ewe PP by SR interaction existed for DTS, with MP lambs at the LSR reaching slaughter weight earlier ( < 0.01) relative to HP lambs, while at the MSR and HSR, MP and HP lambs did not differ from each other. High PP ewes produced a higher average born ( < 0.001) and weaned litter size per ewe ( < 0.01), with live weight weaned per ha ( < 0.001) increasing as ewe PP and SR increased. Lambing difficulty, ewe mother ability and lamb viability did not differ by ewe PP or SR. In conclusion, the lack of interaction between ewe PP and SR on many key performance measures in this study demonstrates the potential to increase the live weight of lamb weaned per ha through the use of higher ewe PP and SR levels, with no effect of ewe PP on lifetime lamb performance even as SR increased, with reductions in lamb performance primarily occurring at the HSR.

Chitosan (N-acetyl-D-glucosamine polymer) is a natural biopolymer, which is the second most abundant organic compound on earth, found in lower plants and some arthropods and crustaceans. Studies with ruminants have shown that supplementing with chitosan can alter ruminal fermentation, including higher propionate concentration and lower acetate to propionate ratio, improving the energy efficiency within the rumen though data on nitrogen metabolism is lacking. Therefore, the objective of this study was to evaluate the effects of chitosan with different dietary crude protein (CP) inclusion on rumen fermentation in beef heifers. Eight ruminally cannulated Belgian Blue x Holstein Friesian heifers (752 ± 52Kg BW) were allocated one of four dietary treatments in a 2 x 2 factorial Latin Square design (n = 8). Diets were offered as total mixed ration (TMR) consisting of grass silage plus concentrate. Diets were offered once daily ad libitum. Dietary treatments were as follows: high CP (16%) +/- chitosan (10g kg-1 DMI) supplementation (HP+) or (HP-) and low CP (12%) +/- chitosan supplementation (LP+) or (LP-). Experimental periods were 25d in duration (14 d dietary adaptation and 10 d sampling). Rumen fluid was collected via cannula every 2 h post feeding for analysis of ruminal pH, ammonia (NH3) and volatile fatty acids (VFA) over a 48-hour period. Data was analysed using Proc Mixed procedure in SAS. Significant differences were considered when P < 0.05. Dietary treatment had no effect on ruminal pH (P > 0.05). Chitosan supplementation had no effect on ruminal NH3 and VFA concentrations (P > 0.05), whereas, animals offered 16% CP had higher concentrations of ruminal NH3 (P < 0.001). In conclusion, supplementing a TMR diet fed to beef heifers with chitosan had no effect on rumen fermentation. However, reducing dietary CP concentration fed to beef animals resulted in lower rumen NH3 concentrations.

This study aimed to quantify the effect of phenotypic factors including birth type, rearing type, age at first lambing, lactation number and their interactions on pedigree lamb performance at 40days and 100days of age (weaning), where nutritional requirements were met at luxury levels. A dataset containing 644,330 lamb weight records from 2010–2017 were retrieved. Two datasets were created; 47,694 forty day weights (20–65 days of age and weighing 12-32kg) and 46,088 weaning weights (66–120 days of age and weighing 20-55kg). The PROC HPMIXED model (SAS 9.4) included gender, age, breed-class, contemporary group and interactions, i.e. birth type*rearing type, and lactation*age at first lambing, with dam as the random effect. At forty days and weaning respectively, lambs born and reared as singles weighed heaviest (20.95kg and 36.83kg) and lambs born and reared as triplets weighed lightest (16.83kg and 31.29kg). There was no difference between lambs born as twins and reared as twins and those born as triplets and reared as singles (18.11kg, 18.38kg and 33.00kg and 33.12kg). Lambs born as singles and reared as twins and those born as twins and reared as singles did not differ (19.01kg, 19.20kg and 34.30kg and 34.64kg), (Table 1, P < 0.01). In first and second lactation respectively, ewes that lambed for the first time as hoggets produced heavier lambs at forty days (18.12kg and 19.30kg) and at weaning (33.06kg and 34.58kg) than ewes who lambed as ewe lambs (16.88kg, 18.54kg and 31.40kg and 33.59kg). By third lactation, weights did not differ between progeny of ewes who first lambed as ewe lambs or hoggets (20.00kg, 19.41kg and 33.77kg and 34.64kg), (Figure 1 and 2, P < 0.05). In conclusion, rearing type significantly alters pedigree lamb performance at forty days and weaning regardless of birth type. By third lactation, production is similar regardless of age of first lambing.

Dry matter (DM) production of multispecies swards compared to perennial ryegrass (Lolium perenne; PRG) swards under intensive grazing warrants investigation as it is relatively unknown. A 5 × 2 factorial experiment, with five sward types and two defoliation methods, was used to investigate the effect of grazing versus cutting on dry matter (DM) production of multispecies and PRG‐only swards. Five sward types were established namely: a PRG‐only sward, receiving 250 kg N ha⁻¹ year⁻¹ (PRG250), and a PRG‐only sward (PRG90), a two‐species sward with PRG and white clover (Trifolium repens; PRGWC), a six‐species sward (6S) and a nine‐species sward (9S), each receiving 90 kg N ha⁻¹ year⁻¹. Cutting plots measured 1.95 × 10 m and grazing plots measured 10 × 10 m. All plots were harvested concurrently every 21–30 days from April‐November for two years (2015 and 2016). A strip from the grazing plots was cut for DM yield determination prior to turning in cattle for grazing. There was an interaction between sward type and defoliation method (p

peer-reviewed The economic value of a trait in a breeding objective can be defined as the value of a unit change in an individual trait, while keeping all other traits constant and are widely used in the development of breeding objectives internationally. The objective of this study was to provide a description of the development of economic values for the pertinent traits included in the Irish national sheep breeding objectives using a whole farm system bio-economic model. A total of fourteen traits of economic importance representing maternal, lambing, production and health characteristics were calculated within a whole farm bio-economic model. The model was parameterised to represent an average Irish flock of 107 ewes with a mean lambing date in early March, stocked at 7.5 ewes per hectare and weaning 1.5 lambs per ewe joined to the ram. The economic values (units in parenthesis) calculated for maternal traits were: €39.76 for number of lambs born (per lamb), €0.12 for ewe mature weight cull value (per kg), −€0.57 for ewe mature weight maintenance value (per kg), −€0.09 for ewe mature weight replacement value (per kg) and −€0.84 for ewe replacement rate (per%). The economic values calculated for lambing traits were: €54.84 for lamb surviving at birth (per lamb), −€0.27 and −€0.30 for direct lambing difficulty in single and multiple-bearing ewes, respectively (per%); the corresponding values for maternal single and multiple lambing difficulty (per%) were −€0.25 and −€0.27, respectively. The calculated economic values for production traits were: −€0.25 for days to slaughter (per day), €3.70 for carcass Conformation (per EUROP grade) and −€0.84 for carcass fat (per fat score). The economic values for health traits were: −€0.24 for ewe lameness (per%), −€0.08 for lamb lameness (per%), −€0.25 for mastitis (per%), −€0.34 for dag score (per dag score) and −€0.08 for faecal egg count (per 50 eggs/g). Within the two Irish breeding objectives, the terminal and replacement breeding objective, the greatest emphasis was placed on production traits across both the terminal (62.56%) and replacement (41.65%) breeding objectives. The maternal and lambing traits accounted for the 34.19% and 23.45% of the emphasis within the replacement breeding objective, respectively. Results from this study will enable the implementation of new economic values within the national terminal and replacement Irish sheep breeding objectives which highlights the traits of importance for increasing overall farm profitability.

Pasture availability in early spring can be limited due to climatic effects on grass production, increasing the likelihood of feed deficits in early lactation of spring-calving pasture-based systems. We hypothesized that restricting pasture allowance (PA) when animals are at peak milk production will have more negative implications on milk production compared with restricting animals before this period. A total of 105 cows were assigned to 1 of 7 grazing treatments from March 14 to October 31, 2016 (33 wk). The control treatment was offered a PA to achieve a postgrazing sward height > 3.5 cm and mean pasture allowance of 15.5 kg of dry matter per cow. The remaining treatments were offered a PA representing 60% of that offered to the control for a duration of 2 or 6 wk from March 14 (mid-March; MMx2 and MMx6), March 28 (end of March; EMx2 and EMx6), or April 11 (mid-April; MAx2 and MAx6). Within grazing treatment, animals were also assigned to 1 of 2 calving dates (early and late) based on days in milk (DIM) on March 14. Early calved (EC) cows were ≥36 DIM, while late calved (LC) were ≤35 DIM. Restricting PA for 2 and 6 wk reduced daily milk yield (−1.6 and −2.2 kg/cow, respectively), cumulative milk protein yield (−4.0 and −6.3 kg/cow, respectively), and cumulative milk solids yield (−5.8 and −9.5 kg/cow, respectively) in the first 10 wk of the experiment. Daily milk yield was similar across the treatments at the end of the 33-wk period (16.8 kg/cow, average of all treatments), as was daily milk solids yield (1.40 kg/cow). Cows in the EC group produced less milk over the first 10 wk of the experiment (20.0 kg/cow per day) compared with the LC animals (22.1 kg/cow per day). However, body weight was greater (+15 kg/cow) in the EC animals compared with the LC, while body condition score was similar (2.85). This outcome indicates that animals that are restricted later in early lactation (circa onset of peak milk production) partition a greater proportion of available energy to maintenance, resulting in greater losses in milk production. These data indicate that despite the immediate reduction in milk production, restricting intake of grazing cows to 80% of that required to achieve spring grazing targets for postgrazing sward height for up to 6 wk may be used as a method of managing short-term pasture deficits on farm with minimal effects on total lactation performance.

The importance of spring grass in the diet of early lactation dairy cows has been widely acknowledged. Numerous studies completed on a plot/paddock basis have identified methods of increasing herbage availability in spring, but little focus was placed on how this impacts animal production. The aim of the current study was to investigate the impact of opening farm cover (OFC; grass availability on farm at turnout in spring; 1036 (high), 748 (medium) and 544 (low) kg DM/ha) and spring rotation length (fast – 56 days and normal – 63 days) on animal performance in early lactation and herbage production and quality. Spring rotation length had little effect on animal performance, herbage variables or sward composition. High OFC increased pre-grazing herbage mass, allowing for increased daily herbage allowance (DHA) compared to medium and low OFC. There was a reduced proportion of leaf in the sward of the high OFC compared to the low OFC, resulting in lower organic matter digestibility. Despite the reduction in sward quality observed as a consequence of achieving high OFC in spring, the greater DHA available to animals increased milk production (+1.4 kg milk/cow/day). Additionally, animals grazing a medium or low OFC had a greater requirement for silage supplementation in spring (+1.3 kg DM/cow/day). The benefits of the higher DHA highlighted in the current study suggest that autumn grazing management must be adapted to increase herbage availability in spring. However, the benefits observed in milk production did not persist beyond the first grazing rotation.

Nitrogen excretion and methane emissions from ruminant production systems are growing environmental concerns. Natural feed additives with known antimicrobial activity are being investigated for their rumen fermentation modification potential and as a strategy to mitigate emissions from livestock. The objective of this study was to evaluate the effects of chitosan source, molecular weight and supplementation level on in vitro (RUSITEC) ammonia and methane production. The experiment consisted of two incubation periods using three RUSITEC systems (8 vessels/system). Treatments were as follows: C0 (control) zero chitosan; C1 chitosan molecular weight 0.10). In addition, C4 increased butyric acid production (P

Beef cattle partition dietary nitrogen (N) into tissues or excrete it in feces and urine, which contributes significantly to water and air pollution. The objectives were to examine the effects of supplementing fresh grass herbage with a low crude-protein, high-energy supplement - citrus pulp - on intake, digestion and N-balance in beef cattle. Sixteen Charolais steers (live weight 585 kg, S.D. 24.1) were used in a randomized block design experiment. Treatments consisted of either unsupplemented zero-grazed grass (predominantly Lolium perenne) harvested 21-d after it received 50 kg N/ha, offered ad libitum (GO), or the same grass supplemented with 2.25 kg citrus pulp DM daily (GS). Following a 21-d dietary adaptation phase, animals were accommodated in metabolism stalls for 10 d (2-d adaptation: 8-d sampling). During this period grass and citrus pulp was offered at 0.85 of the pre-determined daily DM intake; the grass: supplement ratio for GS remained the same as during the adaptation phase. Grass was offered in two equal meals and citrus pulp in one morning meal. Total faeces and urine were collected on a 48-h and 24-h basis, respectively. Data were analysed using AVOVA with terms for treatment and block in the model. Supplementation decreased (P0.05) between treatments. Total N and urinary N excretion were 15 and 23 g/d lower, respectively, and faecal N excretion was 9 g/d greater for GS compared to GO (P0.05). The quantity of N retained and, therefore, N-use efficiency did not differ (P>0.05) between treatments (33 vs. 28 %). Supplementing grass herbage with a low-protein, high-energy feed may be a strategy to reduce total and urinary N excretion in grazing beef cattle.