Grass-legume Silage Research Articles

Day-to-day variation in trace and macro-mineral concentrations in corn and mixed grass–legume silages of Canadian commercial dairy herds

The aims were to assess the day-to-day variation in trace minerals (TM), macro-minerals, dry matter, and physical effectiveness factor in grass–legume and corn silages and to evaluate the variance partition. Grass–legume and corn silage samples were collected in nine Canadian dairy herds during two episodes of five consecutive days at 4 weeks apart by the same individual. All variables were analyzed in duplicate. The proportion of variation due to the farm was more variable within TM than macro-minerals. Using TM software reference values of silages for formulating rations can lead to important errors. Except for physical effectiveness factor, the within-farm variations between sampling episodes were more marked for mixed grass–legume than corn silage. For most of the minerals and nutrients analyzed, the sampling + day-to-day variations were the main source of variability, accounting for over 50% of the within-farm variance for both silage types. The remaining within-farm variance was explained by subsampling and laboratory analyses. The high within-herd variation suggests that a silage sampling over more than 1 day can be useful to get a representative sample for TM analysis. Accurate nutrients and TM values when formulating cow diets is essential to cow health and productivity.

Multiverse analysis and the Bradley-Terry model: A proposed approach for evaluating palatability and preference

The palatability of feed for dairy cows is an important consideration but is difficult to measure, particularly when considering more than 2 feeds. We outline how a combination of multiverse analysis and Bradley-Terry modeling, 2 methodological tools that have rarely been applied in dairy science, can be adapted to address this problem. Specifically, we propose to apply multiverse analysis as a way to consider a range of thresholds for how much of a mixed grass-legume (MGL) silage had to be consumed (as a percent of the total DMI) to be designated as preferred. Each threshold gives rise to a separate dataset and a corresponding fitted Bradley-Terry model. Bradley-Terry models attribute to each feed what is commonly referred to as an “ability” in the context of sports or other competitions but can be interpreted as palatability when applied to feeds. This combined approach is a way of estimating palatabilities that appropriately reflect the degree of preference cows express through their feeding behavior. It has the advantages of being transparent and relatively easy to implement. A possible disadvantage is that this method is limited to a paired comparison approach and has difficulties with main-effects statistical inference. We demonstrate the use of this methodology on an example dataset comparing MGL silages under different ensiling conditions and exposed to oxygen for different durations.

166 Effect of silo type on fermentation characteristics of laboratory-scale silage

Abstract Creating ensiled forage on a laboratory-scale is a tedious and cumbersome process. One must ensure an anaerobic environment for the success of the fermentation while also striving to replicate field-scale conditions. The objective of this experiment was to determine the effect of laboratory-scale silo type on nutritive value and fermentation profiles of grass-legume silage. This experiment was conducted as a generalized complete block design. There was one treatment factor (silo type) with 11 levels: field-scale baleage control (CON), miniature wrapped baleage (MINI), large fermentation bucket (6GAL), small fermentation bucket (2GAL), miniature silo (PVC), pint-sized Mason-type jar with “BurpLid” (BURP), pint-sized Mason-type jar with Ball-brand fermentation lid (BALL), pint-sized Mason-type jar with an airlock lid (LOCK), single-layered vacuum-sealed bag using a chamber-style sealer (CHMB), double-layered vacuum-sealed bag using a chamber-style sealer (HCHMB), single-layered vacuum-sealed bag using a suction-style sealer (FOOD), or double-layered vacuum-sealed bag using a suction-style sealer (HFOOD). Harvest served as the random blocking factor. Forage was harvested from a single alfalfa-bermudagrass pastures at the Wiregrass Research and Extension Center in Headland, AL. Forage was cut 24 h before collection and allowed to sun-cure. After allocation to treatment, samples were allowed to ferment for 56 d. Following fermentation, samples were assayed for NDF, ADF, ADL, CP, pH, mold, and yeast. Dunnett’s test revealed a difference (P < 0.05) from CON for NDF, ADF, and pH. Samples from PVC had 26% greater NDF and 45% greater ADF than CON (58 and 37%, respectively). Samples from BALL were 3 units greater and samples from LOCK were 2 units greater in pH than CON (4.8). When comparing alternative treatments exclusive of CON, there were differences (P ≤ 0.01) in NDF, ADF, ADL, pH, and mold counts among treatments. Results are interpreted to mean that BALL and LOCK are not effective representatives of field-scale silage production due to lack of pH drop, while PVC alters the fiber profiles. All other methods showed promise as prospects for laboratory silage procedures.

Farm management practices and season dependent factors affect the microbial community and chemical profile of corn and grass-legume silages of farms in Ontario, Québec, and Northern New York.

The effects of farm management practices and seasonal variation on the microbial community and chemical composition of corn and grass-legume silage are largely understudied due to the advantages of controlled mini-silo experiments. This study aims to investigate the effects that some key farm factors (use of an inoculant, farm region, and bunker or tower silo) and seasonal variations have on corn and grass-legume silage from farms across Ontario, Quebec, and New York. The silage was either treated with a commercial inoculant (Lallemand Biotal Buchneri 500® or Chr Hansen SiloSolve FC®) or left untreated. The bacterial communities of silage were compared to those of raw bulk tank milk from the same farm to determine if they were similarly affected by management practices or seasonal variations. Family level analysis of the 16S rRNA V3-V4 gene amplicon bacterial community, the ITS1 amplicon fungal community, NMR water soluble metabolome, and mycotoxin LC-MS were performed on silage over a two-year period. Chemical compounds associated with the use of inoculants in corn and grass-legume silage were higher in inoculated corn (acetate, propane-1,2-diol, γ-aminobutyrate; p < 0.001) and grass-legume (propionate; p = 0.011). However, there was no significant difference in the relative abundance (RA) of Lactobacillaceae in either silage type. Leuconostocaceae was higher in non-inoculated corn (p < 0.001) and grass-legume (p < 0.001) silage than in inoculated silage. Tower silos had higher RA of Leuconostocaceae (p < 0.001) and higher pH (p < 0.001) in corn and grass-legume silage. The one farm that used liquid manure with no other fertilizer type had higher RA of Clostridiaceae (p = 0.045) and other rumen/fecal (p < 0.006) bacteria in grass-legume silage than all other farms. Seasonal variation affected most of the key silage microbial families, however the trends were rarely visible across both years. Few trends in microbial variation could be observed in both silage and bulk tank milk: two farms had higher Moraxellaceae (p < 0.001) in milk and either corn or grass-legume silage. In farms using an inoculant, lower Staphylococcaceae was observed in the raw bulk tank milk.

Influence of wilting period on mineral contents of grass-legume silage mixtures in Umudike, South East, Nigeria

Forage conservation in form of silage production remains best option to ensure availability of adequate feed resource in the rainforest zone of Nigeria due to high relative humidity that negatively affects hay quality. Grasses like Panicum maximum (Guinea grass), Pennisetum purpureum (Elephant grass) are predominantly grown in this zone throughout the year, but decline in nutritive quality when dry season was at the peak. Centrosema pubescens (Centro) has been reported to posses good nutritive value which could be explore to improve some nutrients deficiencies in the grass species when incorporated in the silage. This experiment was conducted to evaluate the mineral contents of grass-legume silage mixtures as affected by wilting period in Umudike, Rainforest zone, Nigeria. The experiment comprised two factors namely: wilting period at two levels (6 and 12 hours after chopping) and forage composition in 5 different constituents (sole Panicum maximum (Guinea grass), sole Pennisetum purpureum (Elephant grass), Panicum maximum-Centrosema pubescens (Panicum*Centro: 50:50) mixture, Pennisetum purpureum-Centrosema pubescens (Pennisetum*Centro: 50:50) mixture and sole Centrosema pubescens (Centro). Thus, the experiment was a factorial arrangement laid out in a Completely Randomized Design (CRD). The mineral contents of silage were determined 12 weeks ensiling period. The results showed that wilting period and foragecomposition significantly (P&lt;0.05) affected both macro and micro mineral concentrations of the silage. The ensiled materials wilted for 12 hours respectively recorded the highest values (0.291, 0.419, 0.316, 0.774 and 0.259 %) for Calcium (Ca), Phosphorus (P), Magnesium (Mg), Potassium (K) and Sodium (Na), when compared with 6 hours period of wilting. Meanwhile, Pennisetum*Centro silage mixtures recorded greater concentration of 0.323, 0.436, 0.319, 0.814 and 0.280 % for Ca, P, Mg, K and Na in relation to other forage composition. For micro mineral concentrations, similar (P&lt;0.05) trend was observed on wilting period, while that of fforage composition slightly differed with sole Centro silage recorded the higher Copper concentration (17.58mg/kg). It was evident from the outcome of this study that wilting period and forage composition enhanced the mineral contents of the silage produced in Umudike, rainforest zone, Nigeria. Pennisetum*Centro silage mixture wilted for 12 hours is therefore recommended for ruminant production.&#x0D; &#x0D; &#x0D; &#x0D; &#x0D; La conservation du fourrage sous forme de production d’ensilage reste la meilleure option pour assurer la disponibilité de ressources alimentaires adéquates dans la zone de forêt tropicale du Nigeria en raison de l’humidité relative élevée qui affecte négativement la qualité du foin. Des graminées comme Panicum maximum (herbe de Guinée), Pennisetum purpureum (herbe d’éléphant) sont principalement cultivées dans cette zone tout au long de l’année, mais leur qualité nutritive décline lorsque la saison sèche était à son apogée. Il a été rapporté que Centrosema pubescens (Centro) possède une bonne valeur nutritive qui pourrait être explorée pour améliorer certaines carences en nutriments chez les espèces de graminées lorsqu’elles sont incorporées dans l’ensilage. Cette expérience a été menée pour évaluer la teneur en minéraux des mélanges d’ensilage de graminées et de légumineuses affectées par la période de flétrissement à Umudike, dans la zone de forêt tropicale, au Nigéria. L’expérimentation comprenait deux facteurs à savoir : la période de flétrissement à deux niveaux (6 et 12 heures après la coupe) et la composition du fourrage en 5 constituants différents (sole Panicum maximum (Guinea grass), sole Pennisetum purpureum (Elephant grass), Panicum maximum-Centrosema pubescens (Panicum*Centro : 50 :50), mélange Pennisetum purpureum-Centrosema pubescens (Pennisetum*Centro : 50 :50) et sole Centrosema pubescens (Centro). Ainsi, l’expérience était un arrangement factoriel présenté dans un plan complètement randomisé (PCR). La teneur en minéraux de l’ensilage a été déterminée sur une période d’ensilage de 12 semaines. Les résultats ont montré que la période de flétrissement et la composition du fourrage affectaient de manière significative (P&lt;0,05) les concentrations macro et micro minérales de l’ensilage. Les matériaux ensilés flétris pendant 12 heures respectivement enregistraient les grandes valeurs (0,291, 0,419, 0,316, 0,774 et 0,259 %) pour le calcium (Ca), le phosphore (P), le magnésium (Mg), le potassium (K) et le sodium (Na), par rapport à une période de flétrissement de 6 heures. Pendant ce temps, les mélanges d’ensilage Pennisetum*Centro ont enregistré une plus grande concentration de 0,323, 0,436, 0,319, 0,814 et 0,280 % pour Ca, P, Mg, K et Na par rapport aux autres compositions fourragères. Pour les concentrations de micro-minéraux, une tendance similaire (P&lt;0,05) a été observée pendant la période de flétrissement, tandis que celle de la composition du fourrage différait légèrement avec l’ensilage de sole Centro qui enregistrait la concentration de cuivre la plus élevée (17,58 mg/kg). Il ressort clairement des résultats de cette étude que la période de flétrissement et la composition du fourrage améliorent la teneur en minéraux de l’ensilage produit à Umudike, dans la zone de forêt tropicale, au Nigéria. Le mélange d’ensilage Pennisetum*Centro fané pendant 12 heures est donc recommandé pour la production de ruminants.

Bacteria and methanogen community in the rumen fed different levels of grass-legume silages

Abstract. Ridwan R, Rusmana I, Widyastuti Y, Wiryawan KG, Prasetya B, Sakamoto M, Ohkuma M. 2019. Bacteria and methanogen community in the rumen fed different levels of grass-legume silages. Biodiversitas 20: 1055-1062. This study aimed to investigate the effects of dietary grass-legume silages on the microbial community by using a culture-independent approach. Treatments consisted of R0: 50% Pennisetum purpureum and 50 % concentrate; R1: 20% P. purpureum, 50 % concentrate, and 30% grass-legumes silage; R2: 20% P. purpureum, 35 % concentrate, and 45% grass-legumes silage; and R3; 20% P. purpureum, 20 % concentrate, and 60% grass-legumes silage. The rumen fluid obtained from fistulated cattle was used for T-RFLP, 16S rDNA clone library, and qPCR analyses. The results indicated that bacterial diversity was dominated by Bacteroidetes, Firmicutes, and methanogen by Methanobacteriales, based on partial 16S rDNA sequences. The microbial communities were dominated by Prevotella brevis, P. ruminicola, Succiniclasticum ruminis, and Methanobrevibacter ruminantium, M. smithi, M. thueri, and M. millerae. The increasing silage diet in a rumen suppressed methanogenesis by reducing population distribution of Methanobacteriales, directly or indirectly, by reducing the diversity of bacterial populations. Generally, the increase silage in the diet changed the bacterial and methanogen community. Grass-legume silage diets of less than 45% are potential for ruminant diet to reduce methane production by a decrease of 4% in the relative distribution of methanogens in the rumen.

Production and nitrogen utilization in lactating dairy cows fed ground field peas with or without ruminally protected lysine and methionine.

Previous research has shown that cows fed ≥24% of the diet dry matter (DM) as field peas decreased milk yield as well as concentration and yield of milk protein, possibly due to reduced DM intake and limited supply of Lys and Met. Twelve multiparous and 4 primiparous lactating Holstein cows were randomly assigned to 1 of 4 diets in a replicated 4 × 4 Latin square design. The diets contained (DM basis) 34.8% corn silage, 15.2% grass-legume silage, 5.9% roasted soybean, 2.4% mineral-vitamin premix, 2.0% alfalfa pellets, and either (1) 36% ground corn, 2.4% soybean meal, and 1.3% urea (UR), (2) 29.7% ground corn, 9.8% soybean meal, 0.13% ruminally protected (RP) Lys, and 0.07% RP-Met (CSBAA), (3) 25% ground field peas, 12.3% ground corn, and 2.4% soybean meal (FP), or (4) FP supplemented with 0.15% RP-Lys and 0.05% RP-Met (FPAA). Our objective was to test the effects of FP versus UR, FPAA versus CSBAA, and FPAA versus FP on milk yield and composition, N utilization, nutrient digestibility, ruminal fermentation profile, and plasma concentration of AA. Milk yield did not differ across diets. Compared with cows fed UR, those fed FP had greater DM intake, concentration and yield of milk true protein, apparent total-tract digestibility of fiber, urinary excretion of purine derivatives, and concentrations of total volatile fatty acids in the rumen and Lys in plasma, and less milk urea N and ruminal NH3-N. The concentration of milk urea N, as well as the concentration and yield of milk fat increased in cows fed FPAA versus CSBAA. Moreover, cows fed FPAA had greater ruminal concentration of total volatile fatty acids, increased proportions of acetate and isobutyrate, and decreased proportions of propionate and valerate than those fed CSBAA. The plasma concentrations of His, Leu, and Phe decreased, whereas plasma Met increased and plasma Lys tended to increase in cows fed FPAA versus CSBAA. Concentration of milk true protein, but not yield, was increased in cows fed FPAA versus FP. However, cows fed FPAA showed decreased concentrations of His and Leu in plasma compared with those fed FP. Overall, compared with the CSBAA diet, feeding FPAA did not negatively affect milk yield and milk protein synthesis. Furthermore, RP-Lys and RP-Met supplementation of the FP diet did not improve milk yield or milk protein synthesis, but decreased urinary urea N excretion.

The effect of sward structure and n fertilization on the grass-legume silage quality

The effect of sward structure of the mixtures and nitrogen fertilization on grass-legume silage quality was investigated over two years. The study included Lucerne ( Medicago sativa ) in monoculture and in mixtures with cocksfoot ( Dactylis glomerata ), tall fescue ( Festuca arundinacea ) and sainfoin ( Onobrychis sativa ). Nitrogen fertilizer was applied to the field plots at four different rates: 0, 70, 140 and 210 kg ha -1 . The quality of lucerne silage was inferior to lucerne silage mixed with grasses due to the greater content of ammonia nitrogen (NH 3 -N), acetic (AA) and butyric acids (BA), and reduced content of the lactic acid (LA). Gradual increase of N fertilization significantly has increased the content of NH 3 -N, AA and BA and decreased the content of LA.

Status of vitamins E and A and β-carotene and health in organic dairy cows fed a diet without synthetic vitamins

Synthetic vitamin supplementation is not consistent with organic production, so it is important to investigate whether dairy cows can maintain their health and production without synthetic vitamins being added to their diet. In basic dairy cow diets, provitamin A (β-carotene) and vitamin E are mainly found in pasture and in grass and legume silages, but the concentrations are highly variable. This study compared the vitamin status and health of cows without synthetic vitamin supplementation (NSV group) with control cows (CON group) fed synthetic vitamins according to Swedish recommendations (600 IU of vitamin E and 80,000 IU of vitamin A per cow per day) to investigate whether dairy cows can fulfill their requirements of vitamins A and E without supplementation with synthetic vitamins. Vitamin concentrations in blood plasma and milk, health, fertility, milk yield, and milk composition were measured in Swedish Holstein cows (n=28) during 2 complete lactations. All cows were fed a 100% organic diet containing grass-legume silage, cold-pressed rapeseed cake, peas, cereal grains, and minerals. Blood samples were collected from each cow 3wk before expected calving, at calving, and 3wk, 3 to 5mo, and 7 to 9mo after calving. Samples of colostrum were taken and milk samples were collected 4d after calving and at the same time as the 3 blood samplings after calving. The only difference in vitamin status between groups was found in colostrum in yr 1, when CON cows tended to have a higher concentration of α-tocopherol, and their β-carotene concentration was higher compared with NSV cows. The NSV cows tended to have more cases of mastitis than CON cows in yr 2. Within the NSV group, fewer cows were healthy and more cases of mastitis were observed in yr 2 than in yr 1. The groups did not differ in production parameters. In conclusion, the vitamin status in blood and milk of the studied cows indicated that cows in organic dairy production can fulfill their requirements of vitamins A and E without any supplementation of synthetic vitamins, except at the time around calving, when the requirements are high. However, the impaired health of NSV cows in yr 2 may indicate a long-term negative health effect in cows fed no synthetic vitamins.

Effect of cassava chips on quality of silage from fresh forage sorghum plus Cavalcade forage legume hay mixtures

Two experiments investigated the effects on silage quality of adding cassava chips at a range of levels to a sorghum forage plus Cavalcade legume hay mixture at ensiling at the Experimental Farm, Khon Kaen University, Thailand. Cavalcade hay was 15% of chopped sorghum fresh weight and cassava chips were added at 0, 5, 10 and 15% of chopped sorghum fresh weight. The first experiment utilized sorghum and Cavalcade main crops and the second used the ratoon crop of sorghum and 2 nd cut of Cavalcade. Dry matter percentage of ensiled mixtures and silages increased (P&lt;0.05) with an increase in cassava chip levels in both experiments, but CP and NDF concentrations decreased (P&lt;0.05). Dry matter degradability increased (P&lt;0.05) with an increase in cassava chip levels up to 10% in both main and ratoon/2 nd cut silages. Digestible energy and metabolizable energy of both silages increased significantly with an increase in cassava chip levels up to 10% for main crop and 15% for ratoon/2 nd cut crops. While addition of cassava chips improved digestibility and energy content of silage, it lowered CP concentration. Use of fresh Cavalcade instead of hay should increase the CP levels and should be investigated along with animal feeding studies to test acceptance and animal performance. Keywords: DMD, CP, sorghum silage, grass-legume silage, Centrosema pascuorum , silage additives. DOI: 10.17138/TGFT(2)262-270

Effects of feeding dairy cows different legume-grass silages on milk phytoestrogen concentration

Phytoestrogens are hormone-like substances in plants that can substantially influence human health (positively or negatively), and when fed to dairy cows are partly transferred to their milk. The aim of this study was to investigate the effects of varying the botanical composition and regrowth interval of legume-grass silage on phytoestrogen intake and milk phytoestrogen concentrations. In one experiment, 15 Swedish Red dairy cows were fed 2- or 3-cut red clover-grass silage, or 2-cut birdsfoot trefoil-grass silage. In a second experiment, 16 Norwegian Red dairy cows were fed short-term ley silage with red clover or long-term ley silage with white clover, and the effects of supplementation with α-tocopherol were also tested. High concentrations of formononetin and biochanin A were found in all silage mixtures with red clover. The milk concentration of equol was highest for cows on the 2-cut red clover-grass silage diet (1,494μg/kg of milk). Because of the metabolism of biochanin A, genistein, and prunetin, their concentrations in milk and the apparent recovery were low. Coumestrol was detected in only short-term and long-term ley silage mixtures, and its milk concentration was low. Concentrations of secoisolariciresinol and matairesinol were higher in 2-cut birdsfoot trefoil-grass and long-term ley silage mixtures, those with legume species other than red clover, and the highest grass proportions. The 2-cut birdsfoot trefoil-grass silage diet also resulted in higher enterolactone concentration than the other diets (226μg/kg of milk). Lengthening the regrowth interval increased the intake of secoisolariciresinol and decreased the recovery of lignans. Feeding long-term ley silage resulted in higher milk lignan concentrations but lower milk isoflavone concentrations than feeding short-term ley silage. The apparent recovery of all phytoestrogens except prunetin was highest on the 2-cut birdsfoot trefoil-grass silage diet. No effect of α-tocopherol supplementation was observed on milk concentrations of any of the measured phytoestrogens. Variations were observed in milk concentrations of phytoestrogens, especially of equol, among cows, which could not be explained by variations in diet composition or phytoestrogen intake. The results show that milk phytoestrogen concentration is strongly influenced by silage botanical composition, but questions regarding phytoestrogen metabolism remain to be answered.

Haematological characteristics and performance of West African Dwarf Goats fed crude oil contaminated forage

The effects of feeding crude petroleum contaminated forage on haematological characteristics and performance of 36 young West African Dwarf (WAD) goats was investigated in order to simulate the impact of real crude oil spillage on livestock and game. Graded levels (0.0, 1.5 and 3.0 g per kg forage) of stabilized “Bonny Light” crude oil was incorporated into predetermined quantities of a grass legume silage and fed to the animals. Results showed that blood cell profile was drastically altered with packed cell volume (PCV), granular leucocytes (neutrophils, eosinophils and basophils) increasing linearly (p mortality were observed in the crude oil contaminated diets. It was concluded that crude oil administered at levels of 1.5 and 3.0 g per kg forage to young WAD goats adversely affected blood cell profile, performance and survival rates.

Prediction of Forage Energy Content by Near Infrared Reflectance Spectroscopy and Summative Equations

In livestock nutrition, summative models (SM) are displacing empirical models as a preferred method to predict energy content of forages. The objective of this study was to determine the effect of using near infrared reflectance spectroscopy (NIRS) to determine nutrient subcomponents required of SM on overall ability to predict energy content of corn and legume-grass silages. Corn (n = 90) and legume-grass (n = 70) silages were collected and analyzed for CP, ADF CP, NDF, NDF CP, in vitro (IV) digestible (d) NDF, ash, and fat by standard laboratory techniques. Samples were scanned on a Model 6500 NIRS, and calibration equations were developed for each nutrient. The TDN contents of corn and legume-grass silages were then estimated using a SM, where the model nutrients were determined by laboratory or NIRS methods. The predicted TDN content of corn and legume-grass silages was compared to IV d OM to assess overall utility. The NIRS calibrations were adequate (R2> 0.90) for CP and NDF for both corn and legume-grass silages with standard errors of calibration (SEC) <0.55 for CP and <1.09 for NDF. Near infrared calibrations for ADF CP, NDF CP, fat, and ash were less accurate in both corn and legume-grass silages with R2< 0.75. Calibrations for IV d NDF in corn and legume-grass silages had R2= 0.87 and 0.79, respectively, but possible co-dependency with NDF is speculated. The relationship between corn and legume-grass silage SM TDN and IV d OM was excellent when model nutrients were determined by laboratory procedures. The TDN estimates when NIRS was used to determine all SM nutrients were superior to older empirical models, but SM TDN estimates using NIRS-determined nutrients were less accurate as compared with SM TDN prediction when model nutrients were determined by laboratory procedures. In particular, using NIRS to predict IV d NDF and ash for use in SM lead to the greatest challenge in TDN prediction in both corn and legume-grass silages.

The partial replacement of silage with straw, with or without barley or soybean meal, in rations for winter calving beef cows

The effects of partially replacing grass-legume silage with barley straw, without or with either supplemental energy or protein, were assessed in 72 lactating beef cows. Diets were fed from calving in January-February until turnout to pasture in late May. Performance of cows and their calves was measured over this period, and weight and body condition were measured at weaning in September. Apparent digestibility and N balance of these diets was also assessed in growing steers. Replacing half the silage with barley straw reduced diet digestibility (P &lt; 0.05), intake (P &lt; 0.05), body weight (BW) gain (P &lt; 0.001) and body condition (P &lt; 0.001) of cows but did not affect BW gain or weaning weights of calves. Reproductive performance was also unaffected, although overall production efficiency (kg weaned calf kg-1 cow BW) was impaired (P &lt; 0.10). When the silage-straw diet was supplemented with barley, metabolizable energy (ME) intake was increased to the level supplied by the all-silage diet. However, there was a tendency for cows to partition more ME to calf growth and less to body reserves as indicated by body condition score (P &lt; 0.05). This may have been related to better N utilization, since N losses in urine were lower for steers fed the barley-supplemented mixture than those fed silage (P &lt; 0.01). When the silage-straw was supplemented with soybean meal (SBM) to increase crude protein (CP) to equal the all-silage diet, there were no benefits for the cow or calf, because SBM reduced intake relative to silage fed alone (P &lt; 0.001). Thus, although supplementing with SBM improved N balance, relative to silage (P &lt; 0.01), there was no response in calf performance, probably because of insufficient ME intake in the cow. Although silage appears not to be well balanced for the nutrient requirements of lactating beef cows, attempts to optimise nutrient supply did not markedly improve growth performance of the calf or reproductive performance of the cow. Key words: Beef cow, cow-calf, silage, straw, gains, weaning weight, reproduction

Estimation of intake and digestibility of silage by beef steers using a controlled release capsule of n-alkanes

Twelve beef steers were fed a grass-legume silage either ad libitum or at 70% of ad libitum feeding. Intake and digestibility were measured directly or predicted using the alkane ratio technique. The C32 and C36 alkanes were delivered via a controlled release capsule (CRC) in the rumen. Level of feeding had no effect on digestibility (P &gt; 0.05) but dry matter (DM) intake tended to be greater for steers fed ad libitum (P = 0.08). The release of alkanes from the CRC was erratic and 20% greater than expected. This influenced the exogenous to endogenous alkane ratios. Estimates of intake were therefore derived using both the expected and actual (determined from total collection of feces and their alkane analysis) exogenous alkane release rates. Estimated intakes based on the manufacturers’ release rate were underestimated and associated with high standard errors. For cattle fed restricted silage, estimated intakes obtained with C31:C32, C33:C32 and C33:C36 alkane pairs and using actual measured release rates of exogenous markers were associated with lower standard errors and averaged 87, 102 and 103% of actual values, respectively. For ad libitum-fed cattle the corresponding values were 81, 96 and 96% of actual values. There was no significant difference between actual and estimated DM intake when the C33:C32 and C36:C32 alkane pairs were used. The precision of intake estimates using manufacturers release rates for exogenous alkanes was poor, as evidenced by significant discrepancies (P &lt; 0.05 for four of six estimates) between observed and predicted values averaging 2.26 kg or 30% of DM intake. However, when measured exogenous alkane release rates were used, standard errors were reduced and discrepancies for estimates using C33:C32 and C33:C326 were only 0.4 kg or 6% of DM intake. Fecal recovery of C27, C29, C31 and C33 alkanes was 73.4, 92.7, 85.6 and 100%, respectively. Both C29 and C33 gave good estimates of digestibility because of high recovery. Observed and estimated values were not significantly different. It is concluded that exogenous alkane release from CRCs was not satisfactorily consistent. Reliable estimates of intake could only be made if actual release rate was known. Endogenous alkanes can be used for determination of digestibility, provided fecal recovery is known. Key words: Beef, silage, alkane, intake, digestibility

The performance of primiparous and multiparous beef cows rearing single and simulated-twin calves

One hundred and eighteen Hereford-cross heifers (n = 70) and cows (n = 48) and their offspring were used to evaluate the impact of simulated twinning on weaned calf production and reproductive performance. Twin-calf rearing was simulated by the adoption of a second calf born within 24 h of the birth of the dam's natural calf. In each of 4 yr, cows calved in winter (January–February), were turned out in spring (late May) to rotationally graze grass-legume pastures until weaning in the fall (late September). From calving until turnout cows were given a forage-based diet consisting of either grass-legume silage or hay offered free choice, plus concentrate, the amount of which was 75 or 100% higher for dams in the simulated-twin (ST) than the single (S) treatment. All calves had access to the conserved forage and were given the concentrate ration as creep feed. Estrus detection was performed twice daily beginning 3 wk before and continuing for 4 wk into the breeding season, which consisted of AI for the first 25 d and bull service for the remaining 22 d. In years 2 and 3, the postpartum anestrous period was determined by serum progesterone concentrations. At weaning, S calves weighed more than natural or adopted calves in the ST treatment because weight gain was greater for S calves from birth to turnout. However calf production efficiency (total kilograms calf weaned per kilogram dam weight) was greater for primiparous and multiparous ST than S groups (primiparous 0.85 vs. 0.43 and multiparous 1.62 vs. 0.49; P &lt; 0.05). The ST treatment had no negative effect (P &gt; 0.05) on reproductive performance. As a research tool, this study suggests there are large potential benefits to beef cows raising two, as opposed to one calf. Simulated twinning poses severe management challenges and is not being proposed as a commercial option. However, advances in reproductive technology that could control twinning (e.g., transfer of an embryo a week following AI or twin-transfer of sexed embryos) mean that in future, twin rearing of beef calves may become a feasible option and this study provides valuable information on the post-natal management of cows rearing two calves. Key words: Simulated-twin, progesterone, post-partum, weaning, cow-calf, calves

Serum mineral concentrations in relation to estrus and conception in beef heifers and cows fed conserved forage

A study was undertaken to examine serum mineral concentrations in relation to estrus and first service conception (FSC) in beef cattle fed conserved forage. Blood samples were taken from yearling nulliparous heifers, and suckled 2-yr-old primiparous heifers and multiparous cows at first service which occurred within 12 h of observed standing heat and 21 d after. Serum was analyzed for calcium (Ca), phosphorus (P), magnesium (Mg), potassium (K), sulfur (S), sodium (Na), iron (Fe), copper (Cu), manganese (Mn), zinc (Zn) and boron (B) concentrations by ICAP. Heifers were fed in four groups based on parity and given 3.0 and 2.5 kg hd d–1 of a grain supplement, respectively, plus free-choice grass hay (1.71% K; 0.20% P; 8% protein; 41% ADF). Cows were individually fed ad libitum (21 g kg–1 body weight) grass-legume silage (2.82% K; 0.35% P; 14% protein, 34% ADF). Heifers and cows gained body weight over the breeding season and at turnout had body condition scores of 5 to 6 for heifers and 6 to 7 for cows. Rates of FSC were 53% (10/19), 48% (10/21) and 64% (18/28) for nulli-, primi- and multiparous groups, respectively. Serum Ca, Na, S, Cu, Fe, Zn and Mn did not differ (P &gt; 0.05) between FSC groups, but Na and Cu were higher (P &lt; 0.05) at estrus than at day 21, especially in nulliparous heifers. Concentrations of serum Mg were low (&lt;0.74 mmol L–1) and K high (&gt;4.5 mmol L–1) in heifers and cows but in nulliparous heifers only, serum Mg and K were lowest (P &lt; 0.05) at estrus for those that conceived. Serum B concentrations were generally higher (P &lt; 0.05) in animals that conceived especially on day 21 when B concentrations were higher (P &lt; 0.05) than at estrus. Serum P concentrations were high (&gt;3.5 mmol L–1), but highest in animals that conceived especially on day 21. It is concluded that P and B may be dietary factors limiting first service conception in beef cows fed conserved forage. Key words: Beef cattle, estrus, conception, minerals, boron, phosphorus

Serum mineral concentrations in relation to parturition in beef heifers and cows fed conserved forage

A study was undertaken to examine the relationship between serum mineral concentrations and calving ease in beef cattle fed conserved forage. Jugular blood samples were taken from multiparous cows (n = 6) and 2-yr-old primparous heifers (n = 9) that calved without assistance and 2-yr-old primparous heifers that required assistance with calving (n = 6) on days −7, 0 and +7 after parturition. Sera were analyzed for Ca, P, Mg, K, S, Na, Cu, Zn and B by ICAP and for progesterone by RIA. From 2 mo before and throughout the calving season cattle were given ad libitum round bale grass-legume silage (2.89% K; 3.4% P; 13% CP, 40% ADF; 38% DM). Heifers were also given 0.5 kg hd−1 d−1 of a grain supplement beginning 3 wk before calving. At calving, cows and heifers were in moderate body condition (5.26 ± 0.14 BCS) and heifers had reached 85% of mature body weight (475 ± 26 kg). Serum progesterone concentrations were highest (P &lt; 0.05) at −7 d and dropped below 1 ng mL−1 at parturition and +7 d. Concentrations of serum Mg, S and K were highest (P &lt; 0.05) whilst concentrations of P, B and Cu were lowest (P &lt; 0.05) at parturition. However, serum Mg and S also differed (P &lt; 0.05) among calving groups because concentrations were lowest for heifers with assisted calvings and, serum K concentrations were influenced (P &lt; 0.05) by interaction between calving group and time because K concentrations increased at parturition only in cows and heifers with unassisted calvings. Serum Zn, Ca, and Na were not (P &lt; 0.05) influenced by calving group or time. It is concluded that Mg, S, K, P, B and Cu metabolism are involved in the physiology of parturition and Mg, S and K metabolism may be particularly important for calving ease in primparous beef heifers fed conserved forage. Key words: Parturition, minerals, beef cattle, potassium, boron, magnesium

Consequences of reduction of number of individual feeders on feeding behaviour and stress level of feedlot steers

Thirty-six Hereford steers with an average weight of 230±23 kg, were randomly assigned to one of three groups of 12 animals to determine the consequence of decreasing feeder space on feed consumption, weight gain and stress. The animals were studied over a 28-day trial period. In Group A, each animal had access to an individual electronically controlled Calan Broadbent ® feeder. Groups B and C had access to three and four feeders, respectively. During the trial steers were fed grass legume silage ad libitum with fresh silage added four times daily. Twenty-four hour feed consumption patterns and feed quantity were recorded for each individual steer through time lapse video monitoring of feed disappearance. Blood samples drawn on Days 0, 14 and 28 were analysed for cortisol and differential leucocyte counts. The animals were weighed on these sampling days at 09:00 h. Group A had the longest mean eating time per meal and the lowest number of eating bouts ( P<0.05). Group B had the lowest mean eating time ( P<0.05) but intake of Group B was not different from that of Group A ( P>0.05). Animals in Group B compensated for their shorter times spent at the feeder by increasing their rate of intake compared with those of Groups A and C ( P<0.05). The Spearman rank feeding order correlations for time at the feeder, number of feeding bouts and intake were positive for all groups, indicating that some animals consistently ate the most often and had the greatest intake. Groups A and B both had high Spearman rank feeding order correlations for mean meal length, total time at the feeder and number of feeding bouts ( P<0.05). These high correlations could indicate that subordinate animals were probably not disadvantaged by being fed in a group feeding situation compared with animals fed individually. Neutrophil:lymphocyte ratios did not differ between groups on any sample day ( P>0.05). There were no significant differences in weight gains and cortisol plasma concentrations among experimental groups or time of sampling ( P>0.05). Reduction in number of individual feeders by two-thirds and three-quarters did not influence weight gains and it had no significant effect on stress levels. The results suggest that some degree of competition is desirable in the group feeding situation.

Effects of flavouring agents on intake of silage by feedlot steers

Thirty-five yearling Hereford steers with an average weight of 358 ± 32 kg were randomly assigned to one of five groups of seven animals to determine the effect of adding flavouring agents to grass-legume silage at feeding time. The trial was designed as a 5 × 5 Latin square with each group receiving each of the 5 treatments for a 12-d period. The flavouring agents chosen represented major taste groups: sweet (aspartame (Asp) at 0.025% as fed), acid (hydrochloric acid (HCl) at 0.625% as fed), salt (sodium chloride (NaCl) at 0.6% as fed), and monosodium glutamate (MSG) at 1% as fed. Daily intakes were measured. Monosodium glutamate increased silage intake (P &lt; 0.05). The results suggest that addition of MSG may be of possible practical use as a silage additive to increase silage intake by yearling steers. Key words: Steer, aspartame, monosodium glutamate, intake, flavour, silage