First-cut Alfalfa Research Articles

Dynamics of the bacterial communities and predicted functional profiles in wilted alfalfa silage.

To investigate the fermentation characteristics, bacterial community and predicted functional profiles during the ensiling of wilted alfalfa (Medicago sativa L.). First-cutting alfalfa was harvested at the early bloom stage, wilted for 6h, and ensiled in laboratory-scale silos (1L capacity). Triplicate silos were sampled after 1, 3, 7, 15, 30 and 60days of ensiling, respectively. The bacterial communities of wilted alfalfa and silages on day3 and 60 were assessed through high throughput sequencing technology, and their functional characteristics were evaluated according to the Kyoto Encyclopedia of Genes and Genomes using Tax4Fun. After 60days of ensiling, alfalfa silage showed a moderate fermentation quality, indicated by high lactic acid (56.7gkg-1 dry matter [DM]) and acetic acid (39.4gkg-1 DM) contents, and low concentrations of butyric acid (2.12gkg-1 DM) and ammonia nitrogen (128gkg-1 total nitrogen). Lactobacillus rapidly became predominant on day3 and increased to 60.4% on day60. Results of functional prediction analyses showed that the metabolism of amino acid, energy, cofactors and vitamins were reduced, while metabolism of nucleotide and carbohydrate were increased during ensiling. Fructokinase, 1-phosphofructokinase and pyruvate kinase played important roles in producing lactic acid. The production of acetic acid may be correlated with the enhancement of 6-phosphogluconate dehydrogenase and acetyl-CoA synthetase. Knowledge regarding bacterial dynamics and their metabolic pathways during alfalfa ensiling is important for understanding the fermentation process and may contribute to the production of nutritious and stable alfalfa silage. High throughput sequencing technology combined with 16S rRNA gene-predicted functional analyses could provide a new and comprehensive insight into bacterial community dynamics and functional profiles to further improve the silage quality.

Bacterial inoculant effect on quality of alfalfa silage and haylage

Using of silage and haylage of forage legumes in ruminant nutrition and promotion of promoting proper forage conservation techniques should be an important strategy in livestock production in our country. Forage legumes are difficult to ensile, so it is necessary to apply the starter culture of selected strains of lactic acid bacteria that support the ensiling process and prevent bacterial butyric fermentation and thus contribute to the preservation and improvement of silage and haylage quality. In this paper, the influence of bacterial inoculant ?Silko for alfalfa? on the quality of silage and haylage of alfalfa in two separate trials is presented. The inoculant is a combination of homofermentative lactic bacteria Lactobacillus plantarum and Pediococcus spp. The first-cut alfalfa in the second year was used for silage and haylage. The silage was examined in mini-silos in the laboratory, and the haylage at the cattle farm where the plant material was cuts were collected in experimental silo bags. The treatments were control (untreated silage, i.e. haylage) and silage, i.e. haylage treated with inoculant ?Silko for alfalfa? (rate of 5 ml t-1 fresh material). The silages were analyzed after 90 days, and haylage after 40. The inoculant ?Silko for alfalfa? has been found to maintain the nutritive value of silage and haylage and to improve their chemical, energy and fermentation parameters relative to the control. Since ?Silko for alfalfa? positively affects the correct lactic acid fermentation of silage and haylage and contributes to a lesser loss of nutritional value and energy it is expected that it can promote a high level of productivity of ruminants, and thus contribute to the growth of profit in livestock production.

Effects of inoculants and environmental temperature on fermentation quality and bacterial diversity of alfalfa silage.

To investigate the effects of inoculants and environmental temperature on fermentation quality and bacterial diversity of alfalfa silage, first-cut alfalfa was ensiled with or without two screened lactic acid bacteria (LAB) strains, Lactobacillus plantarum, LP, and Lactobacillus casei, LC. Each treatment was divided into three parts and stored at 20°C, 30°C, 40°C, respectively. After 60days ensiling, fermentation characteristics were measured and bacterial diversity was investigated by 16S ribosomal RNA gene sequencing using Illumina MiSeq platform. LP and LC decreased pH, coliform bacteria counts and increased lactic acid content at 20°C, and the two strains decreased pH, ammonia-N concentration, coliform bacteria counts at 30°C. When the environmental temperature was 40°C, silage treated with LC showed lower LAB and coliform bacteria counts and higher lactic acid content than the untreated and LP treated silages. Butyric acid mainly appeared in silages stored at 40°C. The relative abundance of Lactobacillus in alfalfa silages stored at 20°C and 30°C was highest and increased after LP and LC were added. Garciella was another dominant genus in silages stored at 40°C. In conclusion, LP and LC improved fermentation quality of alfalfa silage by increasing Lactobacillus proportions at 20°C and 30°C; ensiling alfalfa at 40°C was difficult because of Garciella.

In vitro ruminal fermentation of treated alfalfa silage using ruminal inocula from high and low feed-efficient lactating cows

To assess the effect of two additives on alfalfa silage and on invitro ruminal fermentation when using ruminal inocula from high feed-efficient (HE) and low feed-efficient (LE) lactating cows. First- and second-cut alfalfa was harvested at 40% bloom stage, treated with control (no additive), Lactobacillus plantarum (LP) or formic acid (Formic), ensiled in 1·0l minisilos, and fermented for 60days. Fermented alfalfa was incubated invitro for 24h using ruminal inoculum from HE and LE lactating cows. The pH was lower in alfalfa silage treated with LP and Formic, and produced lower ammonia-N than did the control. In vitro true dry matter digestibility (IVTDMD) was higher with ruminal inoculum from HE than LE cows, but there was no consistent effect of treated alfalfa on microbial biomass yield and invitro volatile fatty acids. The IVTDMD was numerically greater with ruminal inoculum from higher feed-efficient cows although statistical significance was only demonstrated with the first-cut alfalfa. However, treated alfalfa silage did not show the effect expected on invitro microbial biomass yield. The feed efficiency of cows used as a source of ruminal inocula may affect IVTDMD and be a source of variation across invitro runs. Differences in ruminal fermentation between cows of different feed efficiency could help to explain differences in milk yield and other parameters of dairy cattle performance.

The effect of bacterial inoculant on chemical composition and fermentation of alfalfa silage

Alfalfa silage is a useful source of protein for feeding ruminants. Therefore, managing alfalfa silage in livestock production systems is an important issue in order to maintain the silage quality and achieve maximum profitable production of milk and meat. The aim of this investigation was to estimate the effects of bacterial inoculant Silko, containing Lactobacillus plantarum (strains: LP1, LP2, LP3 and LP4) on chemical composition, energetic characteristics and fermentation alfalfa silage under field conditions in the commercial dairy farm, during the 2016. The first-cut alfalfa in the second year has been conserved in silage form. The silage mass was subdivided into two equal parts (control (silage without inoculant) and silages treated with bacterial inoculant Silko) and ensiled in trench silo. After 60 days of ensiling, the silages were analysed. Dry matter, ash, crude protein, lactic acid, acetic acid, total digestible nutrients value and relative feed value were significantly higher in silage treated with bacterial inoculant Silko compared to control. Contrary, alfalfa silage treated with a bacterial inoculant Silko had lower values of cellulose, acid detergent fibre, neutral detergent fibre, nonnitro extractive matter, pH, butyric acid, soluble nitrogen/total nitrogen and NH3- N/total nitrogen than untreated silage. Results showed that bacterial inoculant Silko increases silage quality compared to control so that research should be directed toward the use of such prepared silage in ruminant diets and its impact on milk and meat production on farms.

Effects of alfalfa germplasm and stage of maturity on digestive process and productive response of dairy cows fed alfalfa hay-based diets

The effects on the digestive process and the productive performances of dairy cows fed diets containing alfalfa hay from different germplasms and maturity were assessed in the present study. Three different lots of first-cut alfalfa hay were used in the study: the improved variety “Boreal”, harvested at two consecutive maturity stages (early flowering and full flowering) and the ecotype “Vogherese”, at full flowering. Cutting the plant at an earlier stage of maturity improved hay quality in comparison with the more mature forages (crude protein: 21.4 vs 16.5% DM; P<0.01; NDF: 42.2 vs 53.5% DM; P<0.01). The comparison between improved variety and ecotype carried out at the same maturity showed a higher lignin content for the latter (8.6 vs 8.2% DM; P<0.01). Three isocaloric, isonitrogenous and isofibrous diets for lactating cows were formulated using an equal amount of corn silage and the maximum inclusion of one of the tested hays as forage base. The better quality of the early cut hay made it possible to increase its inclusion in the diet up to 44% of total dietary DM, while the two more mature hays covered only 36% of total DM of the respective diets. According to a 3 x 3 Latin square design, the diets were fed to 3 Italian Brown cows (initial average days in milk 121 ± 24 and milk yield 20 kg ± 1.3) fitted with ruminal cannula in 3 consecutive periods of 28 d each. Alfalfa stage of maturity and germplasm did not affect dietary DM intake (average 16 kg/d). Degradability parameters of dietary DM, calculated by in situ nylon bags technique, showed similar kinetics of rumen disappearance for all diets. No differences were noticed in the ruminal rate of passage of the solid phase among diets, while the liquid phase showed a slower rate of passage for the early flowering hay diet. Consistent with the degradation process, the stage of maturity or the alfalfa germplasm did not affect the rumen fluid data or the in vivo digestibility coefficients of the diets. Milk yield did not show any change due to either alfalfa maturity or cultivar, while milk protein was lowered when cows received the early cut hay diet. This result was likely due to an excess of rumen degradable dietary protein which could have been limited by replacing part of the dietary protein sources (soybean meal) with others more resistant to the ruminal degradation.

Effects of Forage Source and Amount of Concentrate on Rumen and Intestinal Digestion of Nutrients in Late-Lactation Cows

The objectives of this study were to determine the effects of dietary forage source with two concentrate concentrations on dry matter (DM) intake, rumen fill, ruminal and intestinal digestibility of nutrients, and duodenal N fractions in lactating cows. Four rumen and duodenal cannulated Holstein cows in late lactation were used in 4 × 4 Latin square design experiment with 21-d periods. Diets were 1) 65% first-cut alfalfa silage and 35% concentrate, 2) 50% alfalfa and 50% concentrate, 3) 65% bromegrass silage and 35% concentrate, and 4) 50% bromegrass and 50% concentrate. Dry matter intake was not affected by forage source but tended to be (P = 0.08) higher for cows fed diets with 50% concentrate. Rumen fill was greater (P<0.01) for cows fed bromegrass compared with those fed alfalfa silage. Ruminal and intestinal digestion of DM was not affected by dietary forage source or concentrate level. Total N intake was greater for cows fed alfalfa-based diets, reflecting the higher crude protein content of alfalfa. However, total N flow at the duodenum was not affected by either forage source or concentrate in the diet. Although forage source influenced the site of digestion of some nutrients no significant effects on total tract digestibilities were observed.

Effects of source of forage and level of concentrate on chewing activity and milk production response in late lactation cows

Four cannulated Holstein cows in late lactation were used in a 4 × 4 Latin square design experiment to determine the effects of forage source with different NDF concentrations and level of concentrate on chewing activity and milk production. Diets were 65% first-cut alfalfa silage with 54% NDF and 35% concentrate, 50% alfalfa and 50% concentrate, 65% bromegrass silage with 65.5% NDF and 35% concentrate and 50% bromegrass silage and 50% concentrate. Diets were fed in 2 × 2 factorial design (silage sources, alfalfa vs. bromegrass and two levels of concentrate, 35 vs. 50%). Dry matter intake averaged 15.2 kg d−1 and was not affected by either forage source or level of concentrate. Intake of NDF was lower for the cows fed the alfalfa-based diet vs. bromegrass silage but the level of concentrate did not affect NDF intake. Time spent eating was not affected by either forage source or concentrate level of the diet. Time spent eating and ruminating kg−1 NDF intake was higher for cows fed alfalfa-based diets than for cows fed the bromegrass-based diets. Total chews g−1 NDF intake tended (P = 0.06) to decrease when cows were fed bromegrass-based diets but eating and ruminating chews g−1 NDF intake were not affected by source of forage or level of concentrate in the diet. Diets with either alfalfa or bromegrass had no effect on daily yields of milk, FCM, fat, protein and lactose. Diets with 50% concentrate increased milk and FCM yields by 11 and 14%, respectively. Fat and lactose yields were also increased by 17 and 11% in cows fed diets with the higher concentrate level. Results suggest that chewing activities during eating and ruminating phases of the eating cycle adjusted for DMI may decrease with increased concentrate level and are not affected by source of forage in the diet. However, chewing activities adjusted for NDF intake are influenced by source of forage but not by level of concentrate in the diet. The results also suggest that yields of both milk and milk components in late lactation cows are influenced by level of concentrate in the diet, while only milk components are affected by source of forage. Key words: Dairy cattle, chewing activity, forage, milk production

The effect of pelleting of alfalfa hay on methane production and digestibility by steers

A modified 2 × 2 factorial experiment with 19 steers was used to study methane (CH 4), CO 2 and heat production and O 2 utilization and the energy digestibility of pelleted and chopped first- and second-cut alfalfa at maintenance and 1.6 times maintenance in steers. Methane production, dry matter digestibility and urinary energy loss were reduced ( P < 0.05) when first-cut alfalfa was pelleted but pelleting had no influence on these parameters with second-cut alfalfa. Methane and CO 2 production and O 2 utilization increased sharply after feeding. There were interactions between type of feed (chopped vs. pelleted) and cut of alfalfa in CH 4 (1 kg −1 feed DM) and CO 2 production and O 2 utilization. Energy digestibility and CH 4 losses were similar at maintenance and 1.6 times maintenance level of feeding. Although methane production was lower in cattle fed pellets in three out of four comparisons of pelleted and chopped hay diets, the decline in energy loss as CH 4 due to pelleting was not sufficient to justify the extra energy expended to pellet diets from an environmental or economic point of view.

Predicting First-Cut Alfalfa Yields from Preceding Winter Weather

In the northern USA, reliable predictions of first-cut alfalfa (Medicago sativa L.) yields could assist producers in forecasting forage availability for the coming season and in deciding whether to replace an existing stand. A mathematical model using over-winter (fall-winter-spring) weather variables was developed for predicting first-cut yield of moderately winter-hardy alfalfa cultivars. Models For the second year, third year, and combined second and third years after seeding were developed using regression analysis of first-cut yields on antecedent overwinter weather data from East Lansing, MI, between 1972 and 1988. Models explained 76 % of variability For second year data, 69 % for third year data, and 65 % for combined data. The three models used either winter temperature cycles (based on fluctuations of daily mean temperature) or winter degree days and spring growing degree days to predict yield. Winter temperature cycles and winter degree days were negatively correlated with yield while spring growing degree days were positively correlated with yield. Validation predictions averaged ± 15 % of measured yields in 1989 to 1992 and 33 % above measured yields in 1993 when conditions not included in the models (i.e., extremely wet fall and spring soil) were major yield determinants. Models like those developed in this study may provide an alfalfa management tool for producers, extension workers, and consultants. These models also may improve the simulation of winter injury in existing alfalfa growth models. Care must be exercised, however, in using any model developed at a single location to predict crop yields in other (especially dissimilar) locations

Additives Containing Bacteria and Enzymes for Alfalfa Silage

First-cutting alfalfa was wilted, harvested from alternate rows, left untreated or treated with additives containing lactic acid bacteria and enzymes (cellulase, amylase, and pectinase), and ensiled in bag silos. Inoculation increased lactic acid bacteria from 5 × 104 to 1 × 106 cfu/g of forage. Because treatments were bagged consecutively, the DM of treated silages was higher than that of untreated silage. However, after 4 d of ensiling, the pH of treated silage, about 4.3, was lower than that of untreated silage, 4.7, and remained lower throughout the ensiling period. After 177 d of ensiling, total lactate was about 25% higher, and ammonia N was about 40% lower, in treated silage. In addition, NDF and ADF contents were lower in treated than in untreated silage. Between 51 and 177 d of storage, glucose content increased in treated silage, but not in untreated silage, suggesting that some plant cell-wall hydrolysis occurred during prolonged storage. In vitro digestion of NDF did not differ among treatments during early incubation, but the extent of digestion after 36 and 48h was lower in treated than in untreated silage. The microbial and enzyme silage additives used in this study improved fermentation characteristics and reduced fiber content of silage but decreased the in vitro digestibility of fiber.

Nitrogen Fertilization in Alfalfa Production

Nitrogen fertilization of alfalfa (Medicago sativa L.) at establishment has been a controversial practice. A review of the literature was conducted to determine conditions when preplant N fertilization of alfalfa resulted in increased yields in the seeding year. Field and lab studies demonstrated that when the soil nitrate levels were greater than 15 ppm and conditions were favorable for effective nodulation (soil pH from 6.2 to 7.5 and high populations of appropriate Rhizobium bacteria present), using preplant N fertilizer in alfalfa establishment did not result in economically important yield increases. Under field conditions that inhibit effective nodulation, alfalfa yield in the seeding year increased when a small amount of N fertilizer (10–50 lb N/acre) was applied. Application of fertilizer N at establishment has been demonstrated to increase yields when soils are low in N (<15 ppm soil nitrate) or organic matter (< 1.5%). Greenhouse and growth chamber research suggests that when alfalfa is established in low N soils that are also relatively cool less than 60°F) for several weeks after planting, a yield increase due to fertilizer N is even more likely. Before deciding to use N in alfalfa establishment, it is necessary to determine levels of soil nitrate and percent organic matter, and to obtain records of soil temperature for the period following the expected planting date. Research Question Using N fertilizer in alfalfa establishment has been a controversial practice. A review of the scientific literature was conducted to determine if applying N fertilizer at establishment results in higher yields in the seeding year. Combining the literature search with our research experience, we provide guidelines to the appropriate use of fertilizer N in alfalfa production. Literature Summary Applying N fertilizer during alfalfa establishment results in economically beneficial yield increases in the seeding year under certain field conditions. In most alfalfa production conditions, however, with favorable soil pH (6.2–7.5) and soil N levels (>15 ppm soil nitrate), applying fertilizer N at establishment did not result in yield increases. When field conditions were not favorable for effective nodulation, first-cut alfalfa yield increased when fertilizer N was applied. This was observed when soil pH was <6.0 or an ineffective inoculant was used. Applying 10 to 50 lb N/acre at establishment increased yields when soils were low in N (<15 ppm soil nitrate) or organic matter (less than 1.5%). The response of alfalfa to N was increased when the average daily soil temperature remained below about 60°F for several weeks after planting. Applied Question Under what conditions is using N fertilizer in aflalfa establishment most likely to result in increased yield? The key to determining the usefulness of fertilizer N in alfalfa establishment is for alfalfa producers to know their soil conditions and to provide favorable conditions for nodulation of alfalfa. Before deciding to use N in alfalfa establishment, it is necessary to determine levels of soil nitrate and percent organic matter, and to obtain records of soil temperature for the period following the expected planting date. The application of 20 to 50 lb N/acre is recommended only when soil nitrate levels are less than 15 ppm, soil organic matter levels are less than 1.5%, and weed control is assured. The likelihood of a yield increase is greater if the average daily soil temperature is less than 60°F for several weeks after planting. Regardless of what decision is made about the use of N in alfalfa production, it is important for the grower to provide favorable conditions for nodulation. This includes adjusting the pH to a minimum of 6.2 and treating seed with an appropriate rhizobial inoculum.

Impact of Stage of Maturity and Method of Preservation of Alfalfa on Digestion in Lactating Dairy Cows

Four multiparous Holstein cows in midlactation were fed 60:40 forage:grain (dry basis) diets containing first-cutting alfalfa harvested at the early bud or early flower stage of maturity. Each of the two maturities was preserved as silage and hay. A 4 × 4 Latin square design experiment (28-d periods) was conducted to measure the impact of alfalfa maturity and method of preservation on milk production and composition, intake, digestion, digesta passage, and particle size of digesta. Milk production and composition were not affected by treatment. Increases in fiber intake resulted from increased maturity and preservation as hay, but this did not appear to limit DMI or milk production. Both increased maturity and preservation as hay resulted in the following effects in cows: more time spent ruminating, greater total chewing time, greater wet and dry rumen fill, and a greater volume of rumen contents. Rumen retention time of La applied to forage was 6h less, and 0-h disappearance of DM from dacron bags was greater for silage than hay. In situ DM disappearance rates averaged 15%/h for silage and 9.5%/h for hay. Lag time was related inversely to 0-h disappearance. Masticates and mixed rumen samples from cows fed hay showed a greater percentage of DM as particles ≥9.5mm in length. Gross feed efficiency was greater for cows fed alfalfa silage than for those fed alfalfa hay, probably because of more rapid digestion and passage. The potential for rumen fill to limit intake in high producing cows appears to be greater for alfalfa preserved as hay than that preserved as silage.

Response of Seedling Alfalfa (Medicago sativa) to Four Postemergence Herbicides

Response of seedling alfalfa to four herbicides applied at the 2nd, 4th, and 8th trifoliate leaf stages was evaluated in 1988 and 1989. There was no interaction between the herbicides and alfalfa growth stages at the time of herbicide application in either year. Bentazon did not reduce alfalfa height or yield of the first cutting in either year. The dimethylamine salt of 2,4-DB and bromoxynil reduced first-cutting alfalfa yield in 1988 and 1989, respectively, and the butoxyethanol ester of 2,4-DB reduced first-cutting alfalfa yield both years. Each herbicide affected one or more measurements of alfalfa quality in at least one year.

Chemical Drying Agents for Alfalfa Hay: Effect on Nutrient Digestibility and Lactational Performance

Effects of chemical drying agents for hay on plasma profile, lactational performance, and nutrient digestibility by cows were studied. First-cutting alfalfa (late bud) was harvested as hay and treated when cut by applying untreated control, a commercial drying agent (7.64kg/ha), or a mixture of active ingredients, potassium carbonate and sodium carbonate (7.47kg/ha). Six multiparous Holstein cows (120 to 150 d postpartum) were fed diets (two cows per treatment) containing 55% hay and 45% concentrate (DM basis) in a balanced two period changeover design. Plasma profiles were similar for all cows, regardless of hay treatment. There were no differences in milk yield, milk fat, or milk protein percentages for control, drying agent, or mixture. Intake of DM was not different among treatments. Apparent digestibilities of DM, OM, CP, NDF, and ADF were not different among treatments. Treatment of alfalfa hay with chemical drying agents did not alter plasma profile, milk production, or nutrient digestibility in midlactation cows.

Winter Sheep Grazing in the Irrigated Sonoran Desert: II. Soil Properties and Alfalfa Regrowth

Irrigated alfalfa (Medicago sativa L.) fields of the Sonoran Desert of the southwest USA produce high quality hay for 9 to 10 mo and also become winter pature for sheep (Ovis aries). Presently, the common practice is to have the sheep graze until only bare ground and grazed alfalfa crowns remain. Our objective was to evaluate the effects of sheep stocking rates on first-cutting alfalfa regrowth and soil physical properties. Water infiltration rate and soil penetration resistance were measured following 0, 200, 400, and 600 head d/acre (equivalent to 40 lambs grazing one acre for 0, 5,10, and 15 d, respectively) of grazing in December and January. Alfalfa yield was taken during the 20 April harvest. Water infiltration rates were high (>0.2 in./h) and were not affected by grazing for this irrigated pasture system, which contradicts the results for rangeland. Hoof action by sheep only effected penetrability in the surface 2 in. (P = 0.024). Alfalfa yield was 5.4% greater (P = 0.089) for the grazed vs. the ungrazed plots. We conclude that intensive winter sheep grazing was not detrimental to plants and soils of the irrigated pastures of the Sonoran Desert.

In Situ Disappearance of Cell Wall Monosaccharides in Alkali-Treated Orchardgrass and Alfalfa

The effect of varying levels of alkali treatment on the composition and disappearance of cell wall monosaccharides in alfalfa and orchardgrass was determined. Two field replicates each of first-cutting alfalfa (bud and midbloom) and orchardgrass (prehead and head) were treated at harvest with 0 (no solution applied), 2, 4, 6, or 8g NaOH/100g forage DM. Forages were hand cut, hand sprayed, and sun cured as hay. Disappearance kinetics of cell wall monosaccharides were measured by suspending polyester bags containing the forages in the cow's rumen for 6, 12, 24, 36, 60, and 72h. Alkali treatment resulted in the following effects on forage NDF: decreased galactose content in mature orchardgrass and decreased glucose content of immature alfalfa; increased disappearance of xylose and glucose in all forages except in mature alfalfa; and increased rate of disappearance of xylose in immature orchardgrass and mature alfalfa and of arabinose in immature orchardgrass. Alkali treatment had limited effects on content of cell wall monosaccharides of two maturities of orchardgrass and alfalfa. Excluding mature alfalfa, alkali treatment increased disappearance of cell wall xylose and glucose in all forages.

Growth and plasma metabolites of lambs weaned to legume pasture at 28 days of age.

Two trials evaluated the potential for weaning lambs directly onto legume pasture at 28 d of age. Ewes and their twin-reared lambs were placed in paddocks on d 19; ewes were removed on d 28. In Trial 1, 60 lambs were allocated to three treatments: unweaned controls (CON1), lambs weaned onto first-cut alfalfa either without supplementary grain (WOG) or with up to 270 g.hd-1.d-1 supplementary grain (WG). Daily gains for the CON1, WOG and WG lambs were 309, 118 and 159 g for the period from d 28 to 40 (P greater than .05) and 241, 195 and 245 g for the period from d 40 to 56 (P greater than .05), respectively. In Trial 2, 80 lambs were allocated to four treatments: weaning onto first-cut alfalfa (early alfalfa, EA), second-cut alfalfa (late alfalfa, LA) birdsfoot trefoil (BFT) and unweaned controls (CON2, pastured on second-cut alfalfa). Daily gains for CON2 lambs were greater (P less than .05) than gains of EA and LA lambs (327 vs 136 and 136 g, respectively) for d 28 to 40, but not different (P greater than .05) for d 40 to 56 (245, 227 and 195 g, respectively). Gains for BFT lambs were lower (P less than .05) than for CON2 lambs for both periods (122 and 136 g, respectively), and BFT lambs appeared to be unthrifty after weaning. By d 32, weaning caused plasma glucose to decline 16.0 mg/dl and plasma nonesterified fatty acids to increase 365 mu eq/liter from preweaning levels. Hematocrit values ranged from 31 to 35% (Trial 1) and 25 to 29% (Trial 2), suggesting that the weaned lambs did not suffer from dehydration. Crossbred lambs can be weaned at 28 d of age directly onto first-cut or second-cut alfalfa.

Electrophoretic Examination of Alfalfa Silage Proteins

Effects of silage additives on proteolysis of ensiled alfalfa were studied using PAGE. First-cutting alfalfa was wilted (40% DM), chopped, and ensiled into 60 × 10-cm polyvinyl chloride silos. Treatments were control or treatment with glucose (50 g/kg DM), ammonium hydroxide (25 g/kg DM), or formic acid-formaldehyde (2:1 mixture of 90% HCOOH:37% HCOH applied at 1.83% of the DM). Samples were collected on d 0, 1, 2, 4, 7, 21, and 50 of fermentation. Samples were analyzed for N, NPN, ammonia N, pH, lactic acid, acetic acid, and soluble sugar. Also, buffer-soluble protein was characterized using PAGE. During fermentation of control silage, pH and concentrations of soluble sugar declined, and concentrations of lactic and acetic acids and NPN increased, indicating a normal fermentation. Similar shifts in concentrations of compounds occurred in treated silage but to a different extent. Proteins from alfalfa herbage and silage were characterized into molecular weight ranges based on relative mobility, and their disappearance with time of fermentation was estimated. Buffer-extractable proteins decreased rapidly with time of fermentation and essentially disappeared by d 7. Proteolysis was inhibited by formic acid-formaldehyde and ammonium hydroxide treatments but not by glucose. Formic acid-formaldehyde decreased the amount of extractable proteins by decreasing their solubility in the extraction buffer. Apparent degradation and extractability of proteins by buffer were affected by silage treatments; however, because buffer-extractable proteins represented only 36 to 40% of total plant proteins, results must be interpreted cautiously until better extraction procedures are developed.

Alkali-Treated Orchardgrass and Alfalfa: Composition and In Situ Digestion of Dry Matter and Cell Wall Components

The effect of varying levels of alkali treatment on composition and disappearance of DM and cell wall components of alfalfa and orchardgrass was measured. Three field replicates of first-cutting alfalfa (bud and midbloom) and orchardgrass (prehead and head) were treated at harvest with 0 (no solution applied or 100% water treatment), 2, 4, 6, or 8g NaOH/100g forage DM. Forages were hand cut, hand sprayed, and sun cured as hay. Alkali treatment decreased the NDF and ADF content of both maturities of orchardgrass; conversely, alkali treatment increased NDF concentration in both maturities of alfalfa. Regardless of maturity, CP content of alfalfa decreased as level of NaOH increased. After 72h of in situ digestion, NaOH increased potentially digestible DM in both maturities of orchardgrass. Disappearance of NDF in mature orchardgrass increased as NaOH increased. Alkali treatment increased the extent of ferulic acid disappearance in immature orchardgrass and increased the extent of p-coumaric acid disappearance in mature orchardgrass. Sodium hydroxide treatment linearly increased the potentially digestible DM and NDF fractions in both maturities of alfalfa. Alkali treatment decreased the rate of DM digestion in alfalfa, regardless of maturity. Alkali treatment altered chemical composition and increased cell wall utilization of both orchardgrass and alfalfa.