Winter grazing stockpiled native warm‐season grasses in the Southeastern United States

In the Southeastern United States, native warm‐season grasses (NWSG) are not harvested during autumn to rebuild root reserves, resulting in de facto stockpiled winter forage. Senesced NWSG forage is considered nutritionally inadequate by temperate livestock managers, but comparable forage is regularly utilized in rangeland systems. This experiment compared the forage characteristics of two NWSG pastures: switchgrass [Panicum virgatum L. (SG)] and a two species mixture of big bluestem/indiangrass [Andropogon gerardii Vitman/Sorghastrum nutans L. (BBIG)] to tall fescue [Festuca arundinacea Schreb. (TF)]. During two winter periods (January‐April), monthly samples were collected and measured for dry‐matter herbage mass (HM), crude protein (CP), in‐vitro true dry‐matter digestibility (48 hr; IVTDMD), neutral detergent fibre (NDF), NDF digestibility (dNDF) and lignin. Across sampling dates, TF provided adequate forage for low‐input animal maintenance (90.3 CP g/kg; 488 g IVTDMD/kg; 4,040 kg DM/ha), while SG had lowest nutritive values and greatest DM (21.0 g CP/kg; 366 g IVTDMD/kg; 7,670 kg DM/ha). Samples of BBIG had results intermediate to SG and TF (32.1 g CP/kg; 410 g IVTDMD/kg; 5,160 kg DM/ha). Leaf sub‐samples of NWSG indicated greater forage nutritive value compared to whole plant samples (e.g., SG: 65 vs 27 g CP/kg respectively). This indicates that selective grazing could allow superior outcomes to those expected from whole plant NWSG nutritive values. Although consistently nutritionally inferior to TF, further research could reveal strategies to make stockpiled NWSG economically useful to livestock managers.     

Proteolysis and in situ ruminal degradation of lucerne ensiled with Cistus ladanifer tannins

The effects of ensiling lucerne with graded inclusion of Cistus ladanifer condensed tannins (CT) on in silo fermentative parameters, in vitro organic matter digestibility (IVOMD) and on in situ rumen degradability of dry matter (DM) and crude protein (CP) were studied. Lucerne forage ( Medicago sativa subsp. sativa ) was sprayed with different solutions of C. ladanifer CT extract in 60 ml of water in order for dose 0 (control), 40 (L40), 80 (L80) and 120 (L120) g of CT per kg of lucerne DM and was ensiled in lab‐scale silos. After 35 days, the silages were analysed for chemical composition, and the in situ ruminal degradability was determined in rams. The inclusion of CT in the silages caused an important dose‐dependent reduction in soluble‐N, NH₃‐N and a large increase in true protein content and N bound with neutral detergent fibre (NDF‐N), which indicates an effective proteolysis reduction during ensiling. Also, the rumen undegradable protein (RUP) increased linearly (P < 0.01) with CT inclusion. However, a linear decrease (P < 0.02) of 5%, 13% and 22% of IVOMD was observed for the silages L40, L80 and L120 respectively. The results obtained suggest that C. ladanifer CT can be used as silage additives to reduce proteolysis of high‐protein forages during ensiling. A level of CT of 40 g/kg DM seems to be the best compromise between the gains achieved by the protection of CP degradation in silo and in the rumen and the losses associated with the depression of the digestion and absorption.     

Effects of perennial ryegrass (Lolium perenne L.) cultivars on herbage production, nutritional quality and herbage intake of grazing dairy cows

Four perennial ryegrass (Lolium perenne L.) cultivars were compared for differences in herbage production, nutritive value and herbage intake of dry matter (DM) during the summers of 2002 and 2003. Two paddocks were sown with pure stands of four cultivars in a randomized block design with three replicates. Each plot was subdivided into fourteen subplots (22 m × 6 m) which were grazed by one cow during 24 h. Twelve lactating dairy cows were assigned to one cultivar for a period of 2 weeks in a 4 × 4 Latin square experimental design; the experiment lasted 8 weeks in each year. Sward structure (sward surface height, DM yield, green leaf mass, bulk density and tiller density) and morphological characteristics were measured. The ash, neutral‐detergent fibre, acid‐detergent lignin, crude protein and water‐soluble carbohydrate concentrations, and in vitro digestibility of the herbage were measured. The sward was also examined for infestation by crown rust (Puccinia coronata f. sp. lolii). Herbage intake of dairy cows was estimated using the n‐alkane technique. Cultivar differences for all sward structural characteristics were found except for bulk density and tiller density in 2003. Cultivars differed for proportions of pseudostem, stem (in 2003 only) and dead material. The chemical composition of the herbage was different among cultivars, with the water‐soluble carbohydrate concentration showing large variation (>0·35). Cultivars differed in susceptibility to crown rust. Herbage intake differed among cultivars in 2002 (>2 kg DM) but not in 2003. Herbage intake was positively associated with sward height, DM yield and green leaf mass. Canopy morphology did not affect herbage intake. Crown rust affected herbage intake negatively. It was concluded that options for breeders to select for higher intake were limited. High‐yielding cultivars and cultivars highly resistant to crown rust were positively related with a high herbage intake.     

Yield,nutritive value and silage fermentation of kura clover‐reed canarygrass and lucerne herbages in northern USA

Excellent winter hardiness, persistence and nutritive value of both kura clover (Trifolium ambiguum M. Bieb.) and reed canarygrass (Phalaris arundinacea L.) suggest that intercropping these species could substitute for lucerne (Medicago sativa L.). The dry matter (DM) yield and nutritive value of herbage, and silage characteristics of kura clover‐reed canarygrass (KC‐RCG) herbage, were compared to those of lucerne over two growth cycles near Arlington, WI, USA. First and second growths of lucerne and KC‐RCG herbage were sampled four times at 1‐week intervals and ensiled for 100 d. Yield of DM of the KC‐RCG was 0·23–0·57 greater than that of lucerne on sampling dates in the first growth cycle, with no differences in DM yield in the second growth cycle. The pH of lucerne silage was lower than that of KC‐RCG silage in the first growth, and the opposite occurred in second growth, which was attributed to maturity differences and the proportion of kura clover in the mixture. Lactate concentration was lower in KC‐RCG than lucerne silages in both growth cycles. The lucerne and KC‐RCG silages had similar in vitro DM digestibility except for the final sampling date in the first growth cycle when neutral‐detergent fibre concentration of KC‐RCG herbage exceeded 550 g kg^?1 DM. Crude protein concentration was greater in lucerne silage than in KC‐RCG silage in both growth cycles. Overall, differences in nutritive value and silage fermentation between the two herbages were minimal across growth cycles. These results suggest that a KC‐RCG sward is a viable alternative to lucerne in northern environments of the USA where lucerne production may be limited by winter injury or edaphic factors.     

Open pasture,silvopasture and sward herbage maturity effects on nutritive value and fermentation characteristics of cool‐season pasture

In Appalachian USA, silvopasture offers promise of increased farm productivity. A synchronized, temporal understanding of open pasture (OP) and silvopasture (SP) nutritive characteristics is essential for grazing system development. We examined pasture‐type nutritive‐value relationships when herbage was harvested based on morphological maturity rather than calendar date. Neutral detergent fibre and acid detergent fibre (ADF and NDF) content were greater in silvopasture, while organic matter (OM) was lower (P < 0·05). Digestibility of SP herbage dry matter (DM) and OM tended (P = 0·10) to be lower (418 vs. 471 and 437 vs. 491 g kg^?1 respectively). Neutral detergent fibre digestibility was greater (P < 0·05) for OP than SP forage (538 vs. 480 g kg^?1), and ADF tended to be greater (P = 0·10; 551 vs. 501). Open‐pasture forage fermentation effluent exhibited slightly higher microbial richness and Shannon diversity than SP. However, overall community composition of both bacteria and archaea did not differ between pasture types or sampling times. Pasture types show proximate analyses differences generally favourable to OP, although both have similar overall nutritive value. In addition, the SP sward exhibited a 4‐ to 6‐days delay in reaching equivalent maturity. Conversion of farm woodlots to SP would increase overall herbage production and improve pasture management flexibility.     

Digestion and nitrogen metabolism in beef cattle and in vitro rumen fermentation of autumn grass differing in fertilizer nitrogen application rate

Beef cattle partition dietary nitrogen (N) into meat or excrete it mainly in faeces and urine, which can contribute significantly to water and air pollution. The effects of two inorganic nitrogen (N) fertilizer application rates—15 (LN) or 80 (HN) kg N/ha—to Lolium perenne‐dominant swards in autumn, on herbage chemical composition, intake, digestion and N balance in beef cattle, and in vitro fermentation and methane production were studied. Four growing beef steers used in a 2 × 2 crossover design experiment were offered zero‐grazed grass harvested 21 days post‐N application between July and October. The same grasses were incubated in an eight‐vessel rumen simulation technique in a randomized complete block experiment. Grass dry‐matter (DM) concentration was 26 g/kg lower and crude protein (CP) concentration was 35 g/kg DM higher for HN compared to LN. There was no difference in herbage DM intake or in vivo DM digestibility between treatments. Nitrogen intake and the digestibility of N were higher for HN compared to LN. Total and urine N loss were 41 and 45 g/day greater, respectively, for HN compared to LN, but faecal N loss did not differ between treatments. The quantity of N retained and therefore N‐use efficiency did not differ between LN and HN (25% vs. 22%). In vitro rumen pH and ammonia‐N concentrations were higher for HN compared to LN, whereas volatile fatty acid concentrations and molar proportions did not differ between treatments. In vitro methane and total gas production were 0.9 mmol/day and 280 ml/day lower for HN than LN respectively. Under the particular conditions of this experiment, reducing fertilizer N application rate reduced total and urinary N excretion, which has potential environmental benefits; however, methane output measured in vitro was increased.     

Morphological development and nutritive value of herbage in five temperate grass species during primary growth: analysis of time dynamics

In a 2‐year field experiment, morphological development and measures of the nutritive value of herbage for livestock during primary growth in Meadow foxtail, Tall oatgrass, Cocksfoot, Perennial ryegrass and Yorkshire fog were investigated. All measured variables were affected significantly by both species and sampling date, and their interaction (P < 0·001), in the period of primary growth. Changes with time in mean stage weight for Meadow foxtail and Cocksfoot were different from the other species due to their indeterminate growth habits. Mean stage weight of Tall oatgrass and Yorkshire fog increased more rapidly than that of Perennial ryegrass with time. Changes in mean stage weight with time were described by linear, parabolic and sigmoid relationships. Crude protein (CP) concentration of herbage was higher for Cocksfoot and Meadow foxtail than for Perennial ryegrass. A parabolic relationship of CP concentration with time was typical for all the species. Concentrations of neutral‐detergent fibre (NDF) and acid‐detergent fibre (ADF) in herbage of the species differed most during the mid‐period of primary growth. Their increases with time showed curvilinear (sigmoid and parabolic) relationships. Perennial ryegrass had lower concentrations of both NDF and ADF in herbage than the other species. Differences between the in vitro dry matter (DM) digestibility among the grasses increased in mid‐ and late periods of primary growth. Perennial ryegrass had higher values for in vitro DM digestibility but the difference from other species was small in the early period of primary growth and from cocksfoot in the late period of primary growth. In vitro DM digestibility showed, in most cases, a sigmoid and, in others, a linear decrease with time. Principal component analysis showed that perennial ryegrass and meadow foxtail were the most distinctive of the species in characteristics relating to morphological development and the nutritive value of herbage to livestock.     

Evaluation of yield and chemical composition of a halophyte (Suaeda glauca) and its feeding value for lambs

Suaeda glauca is a potential feedstock for ruminants in north‐east China in areas of increasing salinity. The characteristics of S. glauca pasture from June to October and effects on intake, digestion and blood metabolites in lambs given increasing proportions of S. glauca in the forage component of a mixed hay/concentrate (50/50) diet were evaluated. Harvest date had a significant effect on dry matter (DM) yield. There were significant increases in DM content, total energy, neutral detergent fibre and acid detergent fibre (ADF), but declines in leaf proportion, crude protein, total ash and sodium contents with maturity. Inclusion of 25%S. glauca hay in a diet significantly improved daily intake of DM, organic matter (OM) and energy compared with T0% and T50% groups. Supplementation at 25 or 50% significantly increased the digestibility of energy, DM, OM and ADF compared with the T0% group. Water intake, urinary excretion, water content of fresh faeces and sodium excretion from urine linearly increased with increasing S. glauca content, but potassium excretion from urine decreased. K and Mg serum contents were significantly increased compared with T0% group when S. glauca made up 50% of diet. This study indicates that S. glauca is a suitable hay when added as 25% of the lamb diet.     

Effect of herbage mass and allowance on sward characteristics,milk production,intake and rumen volatile fatty acid concentration

The objective of this study was to examine the effect of herbage mass and daily herbage allowance (DHA) on sward characteristics and animal performance, dry‐matter intake, rumen pH and volatile fatty acid production of unsupplemented spring‐calving dairy cows throughout the main grazing season. Sixty‐eight Holstein‐Friesian dairy cows were randomly assigned across four treatments (n = 17) in a 2 × 2 factorial design. Two swards were created with different levels of pre‐grazing herbage mass [allocated above 4 cm (>4 cm); 1700 kg DM ha^?1 (medium; M) or 2200 kg DM ha^?1 (high; H)] and two levels of DHA (>4 cm; 16 or 20 kg DM per cow d^?1). An additional eight lactating ruminally cannulated Holstein–Friesian dairy cows were randomly assigned to each treatment in a replicated 4 × 4 Latin square design. Sward and animal measurements were collected across four periods each of 1 week duration in April and May (PI) and July and August (PII). Maintaining the medium‐mass sward across the season improved the nutritive value of the sward in the latter part of the grazing season compared with high‐mass swards, thus resulting in increased animal intakes and milk production throughout PII. The higher organic matter digestibility of the medium‐compared with high‐masses during PII indicates that grazing severity and herbage mass in the spring to mid‐summer period will determine sward quality parameters in the late summer period.     

Characteristics of baled silage made from first and second harvests of wilted and severely wilted forages

First and second harvests of lucerne (Medicago sativa L.), perennial ryegrass (Lolium perenne L.) and a lucerne–perennial ryegrass mixture [80 or 144 g kg^?1 dry matter (DM) of ryegrass] at the first and second harvests were cut and conditioned, wilted to 500 or 700 g DM kg^?1 then baled and stretch‐wrapped for silage on the same dates. Lucerne bales were denser (411 kg m^?3) than bales of perennial ryegrass (331 kg m^?3) (P < 0·05). After an 8‐month storage period, silage made from high DM‐content forage had a higher concentration of neutral‐detergent fibre (NDF) and was less digestible than that made from low DM‐content forage. Daily DM intakes by beef steers, when the silages of the second harvest were fed ad libitum, were 31·2, 31·2 and 22·3 g kg^?1 live weight for lucerne, lucerne–perennial ryegrass mixture and perennial ryegrass silages, respectively (P < 0·01), when the herbage had been wilted to 500 g kg^?1. In vivo digestibility of NDF in the lucerne–perennial ryegrass mixture silage (0·587) was significantly lower than that of perennial ryegrass silage (0·763) but higher than lucerne silage (0·518). Higher intakes of baled lucerne silage tended to offset its lower digestibility values. Lucerne–perennial ryegrass mixture silage had a higher DM and NDF digestibility than lucerne silage, indicating perhaps the presence of associative effects.     

Effect of defoliation frequency and cutting height on growth,dry‐matter yield and nutritive value of Napier grass (Pennisetum purpureum (L.) Schumach)

Growth characteristics, dry‐matter (DM) yield, chemical components and in vitro dry‐matter digestibility (IVDMD) of Napier grass were studied in a randomized complete block design with three replications at Haramaya University, Ethiopia. The treatments were three defoliation frequencies (60, 90 and 120 d after Napier grass establishment) and five cutting heights (5, 10, 15, 20 and 25 cm above ground level). Except for leaf‐to‐stem ratio, all growth characteristics increased with decreasing frequency of defoliation. Similarly, DM yield of Napier grass increased as the frequency of defoliation decreased. Total ash, crude protein (CP), hemicellulose and IVDMD contents of Napier grass increased with increasing frequency of defoliation, whereas DM, acid detergent fibre, acid detergent lignin and cellulose contents increased with a decrease in defoliation frequency. In contrast, cutting heights had no significant effect on most chemical components and IVDMD contents, although total ash and CP decreased as the height of cutting increased. The CP yield per cut and per day was highest at an intermediate defoliation frequency. The results of this study indicated that Napier grass could be categorized under medium‐ to high‐quality herbage if defoliated at 90 d after establishment in the mid and highlands of Ethiopia.     

Nutritive value of ensiled maize stover from nine different varieties harvested at three different stages of maturity

Nutrient composition and digestibility of stover contribute markedly to the nutritive value of forage maize in cattle feeding. Low stover digestibility limits the quality of whole plant maize silage (WPMS) and should therefore be prevented by optimizing management of WPMS production. A project was carried out to analyse nutrient composition and ruminal nutrient degradability of ensiled stover of nine different current maize varieties, which were planted in 3 years and harvested at three maturity stages (50, 55 and 60% ear dry‐matter [DM] content). Variety and harvest date had a significant impact (p < 0.05) on crude protein (CP) and metabolizable energy content, whereas fibre content and non‐fibre components were not affected by these factors. In contrast, the potential and effective degradability (ED) of organic matter (OM), CP and neutral detergent fibre (NDF) were significantly influenced by variety and harvest date. The ED5 (ED at 5% per hour passage rate) of different varieties ranged from 22.9% to 29.3% for OM, from 66.2% to 71.4% for CP and from 17.3% to 20.5% for NDF. The ED5 of OM, CP and NDF declined significantly by 4.1%, 2.5% and 2.1% units between the second and third maturity stage. Almost all investigated parameters were significantly influenced by year. Significant differences between varieties indicate that there is a potential for improvement of stover degradability through breeding. Harvest ear DM content should not exceed 55%, because nutritive value of ensiled stover declines significantly beyond this value, which could negatively affect WPMS quality in cattle feeding.     

CO2 fertilization does not affect biomass production and nutritive value of a C4 tropical grass in short timeframe

Increased atmospheric carbon dioxide (CO₂) is a consequence of recent anthropogenic environmental changes, and few studies have evaluated its effects on tropical grasses used in Brazilian pastures, the main feed source for major part of ruminant livestock. This study evaluated forage production, chemical composition, in vitro total gas production and organic matter degradability of Brachiaria brizantha under contrasting CO₂ atmospheric conditions in a free air carbon dioxide enrichment (FACE) facility. The forage plants were sown in each of the 12 octagonal rings of the FACE facility: six under ambient atmospheric CO₂ concentration of approximately 390 μmol/mol, hereafter referred to as control (CON) plots, and other six rings enriched with pure CO₂ flux to achieve a target CO₂ concentration of 550 μmol/mol, hereafter called elevated CO₂ (eCO₂) plots. Soil samples were collected to determine carbon and nitrogen concentrations. After seventy days of sowing, a standardization cutting was performed and then at regular intervals of 21 days the forage was harvested (ten harvest dates) and forwarded to laboratorial analyses. Forage above‐ground biomass production (dry matter (DM): 6,143 vs. 6,554 kg/ha), as well as morphological characteristics (leaves: 71% vs. 68%; stem: 28% vs. 31%), chemical composition (crude protein: 162.9 vs. 161.8; neutral detergent fibre: 663.8 vs. 664.3; acid detergent fibre: 369.5 vs. 381; lignin: 60.1 vs. 64.1 g/kg DM; total C: 45.9 vs. 45.9; total N: 2.8 vs. 2.8; total S: 0.2% vs. 0.2%), organic matter in vitro degradability (573.5 vs. 585.3 g/kg), methane (5.7 vs. 4.3 ml/g DM) and total gas (128.3 vs. 94.5 ml/g DM) production did not differ significantly between CON and eCO₂ treatments (p > .05). The results indicated that at least under short‐term enrichment, B. brizantha was not affected by eCO₂.     

The effect of initial spring grazing date and subsequent stocking rate on the grazing management, grass dry matter intake and milk production of dairy cows in summer

The objective of this study was to investigate the effects of an early (February; F) or delayed (April; A) primary spring grazing date and two stocking rates, high (H) and medium (M), on the grazing management, dry matter (DM) intake of grass herbage and milk production of spring‐calving dairy cows grazing a perennial ryegrass sward in the subsequent summer. Sixty‐four Holstein‐Friesian dairy cows (mean of 58 d in milk) were assigned to one of four grazing treatments (n = 16) which were imposed from 12 April to 3 July 2004. Cows on the early spring‐grazing treatment were grazed at 5·5 cows ha^?1 (treatment FH) and 4·5 cows ha^?1 (treatment FM) while cows on the late‐grazing treatment were grazed at 6·4 cows ha^?1 (treatment AH) and 5·5 cows ha^?1 (treatment AM). The organic matter digestibility and crude protein concentration of the grass herbage were higher on the early‐grazing treatment than on the late‐grazing treatment. The cows on the FM treatment had significantly (P < 0·001) higher milk (24·5 kg), solids‐corrected milk (22·5 kg), fat (P < 0·01, 918 g) and protein (831 g) yields than the other three treatments. Cows on the FM treatment had a higher (P < 0·001) DM intake of grass herbage by 2·3 kg DM per cow per day than cows on the AH treatment, which had a DM intake significantly lower than all other treatments (15·2 kg DM per cow per day). The results of the present study showed that grazing in early spring has a positive effect on herbage quality in subsequent grazing rotations. The study also concluded that early spring‐grazed swards stocked at a medium stocking rate (4·5 cows ha^?1; FM) resulted in the highest DM intake of grass herbage and milk production.     

THE INFLUENCE OF THE QUANTITY OF HERBAGE OFFERED AND ITS DIGESTIBILITY ON THE AMOUNT EATEN BY GRAZING CATTLE

Six calves, six heifers and six dry cows grazed a mature sward (treatments A and B) and a leafy aftermath (treatment C) in succession. The yields of herbage on the two swards were 7100 lb and 1950 lb DM per acre (7950 kg and 2180 kg per ha), respectively. The amounts of herbage offered daily were 47 lb (21–5 kg) DM per head (treatment A), 70 lb (32 kg) (treatment B), and 60 lb (27 kg) (treatment C), Two estimates of herbage organic–matter intake (O,M,I,) were made on each treatment; records of grazing behaviour were made on treatments B and C, The digestibility of the diet selected on treatment C was higher than that selected on treatments A and B, and the animals ate significantly more O,M, on treatment C, The total grazing times on treatments B and C were similar, but the animals found it more difficult to graze on treatment B
Herbage O.M.I. increased significantly from treatment A to treatment B, even though the quantity of herbage offered per day on treatment A greatly exceeded the amount eaten. The increase in O,M,I, was found to be associated with an increase in faecal 0,M, output, but the digestibility of the diet did not change.     

Relationship between digestibility and faecal nitrogen in sheep and cows offered herbage ad libitum

A comparison was made of the digestibility, voluntary intake and concentration of N in faecal organic matter in castrated male sheep and non-lactating cows offered herbage ad libitum. The sheep ate 22% more herbage DM per kg liveweight than the cows. In general, the sheep and cows digested the organic matter of the herbage to the same extent, although on two occasions significantly higher digestibilities were observed in cows than in sheep. Similar concentrations of N in faecal organic matter in sheep and cows were matched by similar digestibilities of herbage organic matter. Regression equations relating herbage organic matter digestibility to faecal N concentration were not significantly different between sheep and cattle.     

Apparent digestibility and nitrogen utilization of diets based on maize silage harvested at three stages of maturity and fed to steers

Advancing maize crop maturity is associated with changes in ear‐to‐stover ratio which may have consequences for the digestibility of the ensiled crop. The apparent digestibility and nitrogen retention of three diets (Early, Mid and Late) containing maize silages made from maize of advancing harvest date [dry matter (DM) contents of the maize silages were 273, 314 and 367 g kg^?1 for the silages in the Early, Mid and Late diets respectively], together with a protein supplement offered in sufficient quantities to make the diets isonitrogenous, were measured in six Holstein–Friesian steers in an incomplete Latin square design with four periods. Dry‐matter intake of maize silage tended to be least for the Early diet and greatest for the Medium diet (P = 0·182). Apparent digestibility of DM and organic matter did not differ between diets. Apparent digestibility of energy was lowest in the Late diet (P = 0·057) and the metabolizable energy concentrations of the three silages were calculated as 11·0, 11·1 and 10·6 MJ kg^?1 DM for the Early, Medium and Late diets respectively (P = 0·068). No differences were detected between diets in starch digestibility but the number of undamaged grains present in the faeces of animals fed the Late diet was significantly higher than with the Early and Mid diets (P = 0·006). The apparent digestibility of neutral‐detergent fibre of the diets reduced significantly as silage DM content increased (P = 0·012) with a similar trend for the apparent digestibility of acid‐detergent fibre (P = 0·078). Apparent digestibility of nitrogen (N) was similar for the Early and Mid diets, both being greater than the Late diet (P = 0·035). Nitrogen retention did not differ between diets. It was concluded that delaying harvest until the DM content is above 300 g kg^?1 can negatively affect the nutritive value of maize silage in the UK.     

Effect of chitosan on the preservation quality of sugarcane silage

We aimed to evaluate the effects of chitosan and microbial inoculant addition to sugarcane silage fermentation, gas and effluent losses, chemical composition, in situ dry matter (DM), neutral detergent fibre (NDF) degradation and aerobic stability. A completely randomized design with four treatments (n = 40) was performed. It was arranged in a 2 × 2 factorial scheme with chitosan [0 and 6 g/kg of sugarcane DM—1.66 g/kg of natural matter (NM)] and microbial inoculant (0 and 8 mg/kg on NM). Each g of inoculant contained 3.9 × 10¹⁰ UFC/g of Pediococcus acidilactici and 3.75 × 10¹⁰ UFC/g of Propionibacterium acidicipropionici. The addition of microbial inoculant increased lactic acid concentration in silos treated with chitosan. Furthermore, chitosan increased pH and tended to increase acetic acid of silage. In contrast, the inoculant decreased pH and acetic acid, besides increasing ethanol concentration. As chitosan addition increased DM recovery, inoculant addition decreased it. Chitosan decreased NDF and acid detergent fibre (ADF) level and increased DM degradation, while inoculant decreased DM content, DM and NDF degradation. In addition, chitosan improved the aerobic stability only in non‐inoculated silos. Thus, chitosan has a positive effect on silage fermentation, reducing fermentative losses, and improving silage chemical composition and degradation. Conversely, the addition of microbial inoculant negatively affected silage DM recovery, chemical composition, and its association with chitosan decreased the aerobic stability when compared to the exclusive use of chitosan.     

Effect of soya bean oil supplementation and forage type on methane production and fibre digestibility using the in vitro gas production system

We aimed to evaluate the effect of soya bean oil (SBO) supplementation with different forages on in vitro gas production kinetics, methane (CH₄) emissions and potentially digestible neutral detergent fibre (pdNDF) digestibility (IVpdNDFD). Samples of whole‐crop maize silage (MS; Zea mays), sugarcane (SC; Saccharum sp.), perennial ryegrass (RG; Lolium perenne), guinea grass (GG; Panicum maximum) and palisadegrass (PG; Brachiaria brizantha) were incubated with three concentrations of SBO (0, 30 and 60 g/kg of dry matter). The interaction between forage species and SBO inclusion affected molar proportion of acetate, acetate‐to‐propionate ratio, asymptotic gas and IVpdNDFD. Acetate‐to‐propionate ratio numerically decreased from 3.56 to 3.44 and 3.77 to 3.56 for MS and SC respectively. Soya bean oil inclusion at 60 g/kg DM decreased 21.2% and 12.9% of IVpdNDFD for MS and SC respectively. Soya bean oil increase did not affect IVpdNDFD for RG, GG and PG. Soya bean oil inclusion decreased quadratically the asymptotic gas (294–265 ml/g OM) for MS and increased linearly (275–283 ml/g OM) for GG. Lower and greater CH₄ production was observed for RG and SC respectively. Methane production decreased quadratically by SBO increase. Soya bean oil inclusion linearly decreased CH₄ concentration in total gas at 48 hr of incubation from 133 to 128 ml/L. In conclusion, MS and SC are more sensitive to adverse effects of SBO supplementation from 30 to 60 g/kg DM on rumen fermentation when compared to RG, GG and PG.     

Effect of pearl millet silage ammoniated with urea on lamb production and metabolic performance

The objective of this study was to determine the effect of diets containing pearl millet silage ammoniated with urea on the intake, digestibility, production performance, and nitrogen metabolism of lambs. Thirty‐two uncastrated mixed‐breed lambs at 4 to 5 months of age, with an average initial body weight of 17.39 ± 2.16 kg, were distributed into four treatments in a randomized block experimental design with eight replicates. Experimental diets consisted of pearl millet silage ammoniated with urea during ensiling at the levels of 0, 20, 40, and 60 g/kg dry matter (DM). Increasing urea levels in the pearl millet silage led to a linear decrease (p < .05) in the intakes of DM, organic matter, and total digestible nutrients by the lambs. Total and average daily weight gains decreased linearly (p < .05) with the addition of urea to the silage. Intake and digestibility of crude protein, nitrogen intake, urine urea nitrogen, plasma urea nitrogen, microbial synthesis, and microbial efficiency had a quadratic response (p < .05) to the urea levels in the silage. Pearl millet silage ammoniated with urea reduces dry‐matter intake and daily weight gain in lambs. Urea is not recommended for use in the ensiling of pearl millet.