In Vitro Dry Matter Disappearance Research Articles

Defoliation Intensity Effects on Season‐Long Dry Matter Distribution and Nutritive Value of Tall Fescue

Implementation of intensive grazing management requires knowledge about pasture growth rates and nutritive value throughout the grazing season. Such information is lacking because results from small-plot defoliation experiments generally focus on annual dry matter yields (DMYs) and season mean nutritive value. In this experiment, the influences of defoliation treatments on daily growth rate (DGR) and associated nutritive value of tall fescue (Festuca arundinacea Schreb.) throughout the growing season were evaluated. A 3-yr study was conducted on a Typic Kanhapludult soil near Raleigh, NC. Eight defoliation treatments (31-, 15-, 10- and 8-cm canopy heights cut to a 5-cm stubble; 31-, 15-, and 11-cm canopy heights cut to a 9-cm stubble, and an 8-cm canopy height cut to a 4-cm stubble) were evaluated in a randomized complete block design. Daily growth rates (kg ha -1 ) were significantly (P ≤ 0.01) altered by defoliation treatments and by years within treatments. When rainfall was near normal in both spring and late summer, tall fescue growth rates, depending on defoliation treatment, ranged from 34 to 55 kg ha -1 d -1 in May, from 7 to 18 kg ha -1 d -1 in late July, to 22 to 35 kg ha -1 d -1 in late September. In less favorable years, DGRs seldom exceeded 30 kg ha -1 d -1 in the spring or 15 to 30 kg ha -1 d -1 in the autumn. Depending on defoliation treatments, in vitro dry matter disappearance (IVDMD) ranged between 650 and 733 g kg -1 in the spring, 479 and 687 g kg -1 in midsummer, and 549 and 807 g kg -1 by late summer. Crude protein (CP) and detergent fiber fraction concentrations were also examined. The approach used to estimate DGR and associated nutritive value changes throughout the growing season resulted in useful data that can be applied in developing intensive grazing management practices.

Genetic analysis of feed quality and seed weight of sorghum inbred lines and hybrids using analytical methods and NIRS

Summary Eight lines of grain sorghum and their F1 hybrids were evaluated for contents of crude protein (CP), fat (FAT), and starch (STA); protein digestibility (PD); and in vitro dry matter disappearance (IVDMD). The effect of seed weight (SW) on these traits and the potential use of near infrared reflectance spectroscopy (NIRS) to predict them also were investigated. The male lines included three normal-seeded lines (TX2737, TX435, and P954063) and two largeseeded lines (PL-1 and Eastin1). The female lines included common U.S. seed parent lines (Wheatland, Redlan, and SA3042). The lines and their hybrids were grown under dryland conditions at Kansas State University experiment fields in Ashland and Belleville, Kansas, in 1999. The experiments were conducted using a randomized complete block design with four replications at each location. The effect of genotype was significant for all measured traits. The male parent lines were highly variable and expressed high levels of genetic variation in combining ability for CP, PD, STA, and SW. The female parents were genetically more uniform; however, significant general combining ability effects were noted for PD and SW. Significant negative correlations were noted between CP and STA and between SW and STA. Significant positive correlations were found between CP and SW and between FAT and IVDMD. Crude protein content was predicted accurately by NIRS. Fat content and IVDMD could not be predicted by NIRS. The NIRS equations based on ground samples were more accurate than those based on whole-seed samples.

Yield and quality of three corn hybrids as affected by broiler litter fertilization and crop maturity

Specific hybrids, fertilization and maturity impact yields and nutrient quality of corn silage. To address these effects, three corn hybrids ( Zea mays L.) (Pioneer 3136, 3140, 3154) with five N fertilization (F) treatments were planted for 2 years and harvested at approximately 1/3, 2/3 or 100% milk line in a split–split plot design. Main treatments were No-F, 4.5, 9.0, 13.5 (Year 1) or 18.0 (Year 2) Mg ha −1 of broiler litter (BrL) or 202 kg ha −1 of NH 4NO 3. At harvest, milk lines and whole plant, stover and grain yields were determined. Whole plant and stover portions were chopped and subsampled for subsequent nutrient component and in vitro dry matter disappearance (IVDMD). Milk line advanced rapidly, especially during Year 1 that was a dry year. Whole plant yields were greatest for the 13.5/18.0 BrL treatments with no difference between 9.0 BrL and NH 4NO 3 treatments. Nutrient content varied with fertilizer treatment and year; during Year 1, NH 4NO 3 treatments had greater CP and lower ADF values, but the 13.5/18.0 BrL had the greatest CP content in Year 2, a wetter year. Whole plant IVDMD values were greater for NH 4NO 3 than the 13.5/18.0 BrL treatments during both years, but this occurred only during Year 1 for stover. Corn hybrid did not consistently affect yield, but during both years stover ADF was lower and IVDMD was higher for Hybrid 3136. These advantages existed in the whole plant only during Year 1. Increased maturity enhanced grain and whole plant yield, but effects on nutrient quality were variable. Appropriate application rates of BrL provide comparable yields to commercial fertilizer without an adverse effect on nutrient composition, although digestibility may be reduced.

Avaliação de clones de capim-elefante (Pennisetum purpureum Schum.) e de um híbrido com o milheto (Pennisetum glaucum (L.) R. Br.) submetidos a estresse hídrico. 2. Valor nutritivo

O objetivo deste trabalho foi avaliar o valor nutritivo de três cultivares de capim-elefante (Cameroon, Roxo de Botucatu e Mott) e de um híbrido de capim-elefante com o milheto (híbrido HV-241), cultivados sob diferentes condições de umidade (com e sem estresse hídrico). Utilizou-se o delineamento em blocos ao acaso com parcelas subdivididas e três repetições. Na parcela principal, estudou-se o efeito dos regimes de umidade e nas subparcelas, os diferentes clones. Foram avaliados os teores de matéria seca (% MS), proteína bruta (PB) e fibra em detergente neutro (FDN) e a digestibilidade in vitro da matéria seca (DIVMS). Os materiais submetidos a estresse hídrico apresentaram elevado grau de dessecação (mais de 58% de MS), sobretudo os cultivares de capim-elefante. As plantas submetidas a estresse hídrico apresentaram teores de PB (17,58%) significativamente superiores aos das irrigadas (14,45%), sendo que, entre os cultivares, apenas o Cameroon (14,68% PB) diferiu dos demais (16,46% PB). Quanto aos teores de FDN, não se verificou diferença entre os dois regimes de umidade, mas os cvs. Mott e Cameroon apresentaram teores superiores (61,79%) aos do cv. Roxo de Botucatu e do híbrido HV-241 (56,60%). Não foi verificada diferença na DIVMS entre os regimes de umidade nem entre os diferentes clones, sendo o valor médio de 53,07%.

Aditivos na conservação do bagaço de laranja in natura na forma de silagem

Estudaram-se os efeitos de aditivos na fermentação e composição do bagaço de laranja, em silos laboratoriais de PVC com capacidade para 15 kg, distribuídos ao acaso com três silos por tratamento: sem aditivo (CT), inoculante enzimático microbiano (IN) e ácidos fórmico (FO), propiônico (PP) e acético (AC). As amostras foram tomadas antes (0) e 2, 8, 16, 32 e 64 dias após a ensilagem. Analisaram-se os teores de matéria seca (MS), proteína bruta (PB), fibra em detergente neutro (FDN) e detergente ácido (FDA), a digestibilidade in vitro da matéria seca (DIVMS) e da parede celular (DIVPC), o pH, a capacidade tampão (CATP) e o N amoniacal. A silagem sem aditivo apresentou os menores teores de MS. Os teores de PB, FDN e FDA da silagem tratada com ácido fórmico (FO) foram os menores. As DIVMS e DIVPC foram constantes, com exceção do tratamento com ácido fórmico (FO), que foi linear negativo, em função do tempo de ensilado. O comportamento do pH apresentou equações de regressão cúbicas, com exceção do tratamento com ácido fórmico, que foi linear. A silagem tratada com ácido fórmico apresentou os menores valores de CATP (25,7 a 39,1 mg HCl/100 g MS) e os maiores de N amoniacal (3 a 4% N total). Os aditivos não melhoraram a qualidade e o valor nutricional da silagem de bagaço de laranja

Yield and Quality of Wheat, Triticale, and Elytricum Forage in the Southern Plains

Hard red winter wheat (Triticum aestivum L.) is a major cool‐season forage that couples with warm‐season perennials to provide livestock feed in the Southern Plains. Productivity and quality of wheat forage declines in April, creating a forage deficit period until warm‐season perennial grasses are available. Other cool‐season annual grasses with different growth patterns may provide growth during this period to fill this forage deficit. A field experiment was conducted on Brewer silty clay (fine, mixed, superactive, thermic Udertic Argiustoll) from 1994 to1997 to compare seasonal forage production patterns and yield and quality of winter wheat, triticale (× Triticosecale rimpaui Wittm.) and × Elytricum spp. (Triticum aestivum × Elytrigia spp. ‘OK‐906’). Aboveground whole‐plant biomass during late fall and early spring were greater for wheat than elytricum, but this trend was reversed in late spring and early summer. Average growing degree days to reach physiological maturity were 2500, 2670, and 3100 for wheat, triticale, and elytricum, respectively. Averaged across years, triticale and elytricum reached maturity 8.5 and 28 d after wheat, respectively. At physiological maturity, differences in biomass accumulation between wheat and triticale were minimal, but elytricum at physiological maturity produced 22% more total biomass, 3.5% less grain, and 28% greater straw yield as compared with wheat. Differences in straw in vitro dry matter disappearance (IVDMD) among species were minimal. Because of its prolonged vegetative‐growth phase compared with wheat or triticale, elytricum has the potential to fill the late spring forage deficit period and reduce supplemental feed cost for livestock.

Lamb production and forage quality under a forage system consisting of AU Triumph tall fescue and Tifton 44 bermudagrass

The lamb production potential and forage quality of a forage system consisting of AU Triumph fescue and Tifton 44 bermudagrass was studied over a period of two consecutive years. Each spring, 60 yearling Suffolk ewes and 40 wethers were divided into two groups and allowed to graze two replicated 1 ha AU Triumph paddocks continuously. At the end of the spring grazing season, both groups were transferred to two replicated 1 ha Tifton 44 paddocks for summer grazing. Body weight was recorded fortnightly and composite forage samples analyzed for chemical composition, in vitro dry matter disappearance (IVDMD) and in vitro organic matter disappearance (IVOMD) at the end of the study. Mean crude protein (CP), ether extract (EE), ash, neutral-detergent fiber (NDF), acid-detergent fiber (ADF), cellulose, lignin, IVDMD and IVOMD contents of AU Triumph fescue were 13.26, 1.86, 7.38, 69.4, 36.37, 29.2, 6.81, 64.44 and 62.88%, respectively. The corresponding values for Tifton 44 bermudagrass were 7.5, 1.01, 5.2, 78.3, 41.0, 28.3, 8.8, 56.97 and 55.61%. Average daily gain (ADG) and lamb gain per hectare on AU Triumph fescue were 142.1 g and 412.59 kg/ha, respectively. However, lamb ADG started to decline and remained low when they were transferred from AU Triumph to Tifton 44 bermudagrass resulting in a low ADG and lamb gain per hectare of only 18.2 g and 84.09 kg/ha, respectively. In contrast, Tifton 44 yielded higher post grazing residual DM, suggesting that the decline in performance of the lambs grazing Tifton 44 to be related to poor forage quality rather than availability. The results indicate that low nutritive value of Tiftton 44 bermudagrass is a limiting factor to lamb production in the forage system studied. To prevent the observed decline in lamb performance, it might be necessary to fertilize Tifton 44 at a higher rate or replace it with a better quality warm season forage.

Genotypic differences in chemical composition and ruminal degradability of oat hulls

A study was conducted to determine differences in chemical composition and ruminal degradability of oat hulls derived from ten oat varieties. Hulls derived from AC Assiniboia had a lower (P < 0.05) acid detergent lignin (ADL) and a higher (P < 0.05) in vitro dry matter disappearance (IVDMD) relative to the other nine varieties. Effective ruminal degradability of neutral (NDF) and acid (ADF) detergent fiber for AC Assiniboia hulls were higher (P < 0.05) than those of Calibre hulls and similar to those of Calibre straw. Key words: Oat hulls, chemical composition, ruminal degradability

Summer Accumulation of Tall Fescue at Low Elevations in the Piedmont: I. Fall Yield and Nutritive Value

Summer accumulation of tall fescue (Festuca arundinacea Schreb.) for fall and winter use in the Piedmont, a region of the USA of moderate fall and winter temperatures and open winters of frequent rainfall, has not been well documented. We determined in this 5‐yr study the yield and nutritive value in mid‐November of tall fescue accumulated monthly from 1 June to 1 September. A fifth treatment included an additional 67 kg N ha−1 applied at the 1 July accumulation date. The site was a Cecil clay loam (fine, kaolinitic, thermic Typic Kanhapludults) soil and the treatments were arranged in a randomized complete block design with four replicates. Summer accumulations yielded from 3280 to 4130 kg ha−1 with a mean linear (P ≤ 0.05) reduction in dry matter of 195 kg ha−1 for each week's delay in accumulation from 1 June until 1 September. In two of the three years, highest (P ≤ 0.05) dry matter yields (DMY) resulted from the 1 June date (4070 to 5440 kg ha−1) and lowest (P ≤ 0.05) from the 1 September date (1010 and 860 g kg−1). Repeated summer accumulations did not alter DMY (P < 0.01) in subsequent falls or in the following spring. At mid‐November in vitro dry matter disappearance (IVDMD) had increased 30 g kg−1 for each 30‐d delay in accumulation from 1 June to 1 September, but no change occurred in crude protein (CP) (mean = 120 g kg−1). Summer accumulation of tall fescue for fall grazing can be practiced in the lower Piedmont with accumulation beginning as early as 1 June.

Avaliação da folha e do colmo de topo e base de perfilhos de três gramíneas forrageiras: 1. Digestibilidade in vitro e composição química

RESUMO - Foi avaliado o grau de correlação linear simples entre a digestibilidade in vitro da matéria seca (DIVMS) e a composição química de lâminas e bainhas foliares e, do colmo, amostrados no topo e na base de perfilhos de capim-elefante (Pennisetum purpureum, cv. Mott), capim-setária (Setaria anceps, cv. Kazungula) e capim-jaraguá (Hyparrhenia rufa, Nees Stapf ). Os valores de DIVMS e os teores de proteína bruta (PB) e parede celular (FDN) exibiram gradiente ao longo do perfil do perfilho e diferença entre as frações do perfilho. As folhas situadas no topo do perfilho mostraram maior conteúdo de PB e digestibilidade, apesar dos mais altos teores de FDN, que as folhas situadas na base dos perfilhos. As lâminas foliares mostraram valores relativamente mais altos de DIVMS, PB e FDN que a bainha foliar. Nenhuma correlação foi observada entre os componentes químicos e a DIVMS da lâmina foliar do topo do perfilho. Apenas o teor de lignina apresentou correlação significativa (r = - 0,53) com a DIVMS, quando dados das lâminas foliares de topo e base do perfilho foram agrupados. Os teores de fibra em detergente neutro, fibra em detergente ácido, proteína bruta e lignina propiciaram correlações com a DIVMS da lâmina foliar de base, da bainha foliar e do colmo.

Avaliação da folha e do colmo de topo e base de perfilhos de três gramíneas forrageiras: 2. Anatomia

RESUMO - A proporção de tecidos, o grau de correlação linear desta característica com a digestibilidade in vitro da matéria seca (DIVMS) e sua composição química foram determinadas em seções transversais das frações botânicas, lâmina e bainha foliares e colmo, amostrados no topo e na base de perfilhos de capim-elefante (Pennisetum purpureum, cv. Mott), capim-setária (Setaria anceps, cv. kazungula) e capim-jaraguá (Hyparrhenia rufa). O capim-jaraguá, com maior proporção de bainha parenquimática dos feixes (BPF) na lâmina foliar e de tecido vascular lignificado (TVL) e esclerênquima (ESC) na lâmina e bainha foliares, apresentou proporção de tecidos menos compatível à de uma forrageira de alto valor nutritivo, em comparação ao capim-elefante e capim-setária. As lâminas foliares caracterizaram-se por apresentar alta proporção de epiderme e baixa proporção de ESC, TVL e células parenquimáticas (CPA) em relação à bainha foliar e ao colmo. A proporção de ESC mostrou correlação negativa com a DIVMS da lâmina foliar de topo, do colmo e do total das frações do perfilho. A proporção de CPA correlacionou positivamente com a DIVMS da bainha foliar, r = 0,68, enquanto a proporção de TVL apresentou correlação positiva com a DIVMS, quando todas as frações do perfilho foram consideradas, r = 0,31. As proporções de BPF, TVL e ESC correlacionaram positivamente com os teores de fibra em detergente neutro e fibra em detergente ácido das forrageiras, enquanto as proporções de mesofilo e epiderme apresentaram correlação negativa.

Sequence Grazing Systems on the Southern Plains

Eastern gamagrass (Tripsacum dactyloides (L.) L.) is a perennial warm-season bunchgrass that starts growth earlier in the spring than most other warm-season grasses. This suggests that combining eastern gamagrass with other warm-season grasses in a sequence grazing system could lengthen the period of rapid livestock gain. We studied sequence grazing systems consisting of eastern gamagrass and Old World bluestem (Bothriochloa ischaemum L.) (EG-OWB) as compared to native mixed prairie and Old World bluestem (Native-OWB) from 1993 to 1997. Crossbred beef steers averaging 239 kg grazed eastern gamagrass or native pasture from early May to early June and again from late July through August. Old World bluestem was grazed in mid season. We measured forage yield and nutritive value and steer gain. Standing forage of eastern gamagrass above a 15-cm stubble height averaged 895 kg ha-1 at the start of the first grazing period and 2,430 kg ha-1 at the start of the second grazing period. Dry, cold winter and spring weather reduced this amount to 80 kg ha-1 in May 1996 and precluded grazing the eastern gamagrass that season. Crude protein content of eastern gamagrass was greater than 14% and in vitro dry matter disappearance (IVDMD) was greater than 65% in May. By August, crude protein content had dropped to 5-8% and IVDMD was 45-50%. Peak standing crop of Old World bluestem averaged 4,580 kg ha-1 over years. Steer gain over the entire grazing season, 103 days, did not differ between forage systems, averaging 1.02 kg head-1 day-1 in both systems. Steer gain was higher on native pasture than eastern gamagrass in the late grazing season (0.91 versus 0.60 kg head-1 d-1, p=0.02). As a result of higher stocking rates, steer gain was 257 kg ha-1 for the EG-OWB system and 103 kg ha-1 for the Native-OWB system (p<0.01).

Summer foraging on Scots pine Pinus sylvestris by moose Alces alces in Sweden ‐ patterns and mechanisms

Scots pine Pinus sylvestris is a dominant winter food species to moose Alces alces in Fennoscandia but reports of its use during the growing season are limited. Browsing by moose on current‐growth, terminal shoots of Scots pine (CGTS) during summer was studied in three areas in southern and central Sweden to quantify this seasonal feeding habit. Dynamics of nutrient content in CGTS were also studied to relate the timing of consumption to the changing qualitative value of this forage. To determine the temporal pattern of browsing by moose, data were taken in young pine stands of two separate areas during the growing seasons of two different years, 1980 and 1995. In the former year use of terminal shoots peaked in mid‐June while in the latter year it peaked some two weeks earlier. Nutrient analyses, made only in 1995, showed that peak use of pine terminal shoots coincided with seasonal highs in magnesium (Mg), potassium (K), crude protein (CP), phosphorus (P), starch and total carbohydrates, and seasonal lows in acid detergent fibre (ADF) and acid detergent lignin (ADL). In vitro dry matter disappearance (IVDMD), a measure of digestibility, in terminal shoots in June was found to be significantly higher than in two other important moose browse species, birch Betula spp. and bilberry Vaccinium myrtillus. To determine frequencies of use of CGTS and heights of recently browsed trees, young pine stands in a third area were surveyed in July 1985. All browsed pine trees were between 30 and 230 cm in height, and 14% were browsed on some occasion during the growing season. Our results are discussed with respect to the potential mechanisms underlying summer use of CGTS by moose. Further research on the impact this feeding habit may have on forestry is suggested.

Fiber Digestion Dynamics of Sward Components within Switchgrass Populations

Forage quality as it relates to plant maturity is well established; however, strategies for improving fiber digestion in switchgrass populations have not been determined. The objectives of this study were to determine fiber digestion of sward components within switchgrass (Panicum virgatum L.) populations and which aspects of fiber digestion dynamics caused in vitro dry matter disappearance (IVDMD) differences of six switchgrass populations. This study was conducted in 1993 near Ames, IA, and Mead, NE. The experimental design was a randomized complete block design with a split-plot arrangement of treatments with four replicates at each location. Whole plots were populations and subplots were sward maturity. Trailblazer', 'Pathfinder', 'Cave-in-Rock', and three experimental switchgrass populations were used in this study. Populations were harvested on 9 June, 19 July, and 27 August at Ames and on 10 June, 27 July, and 26 August at Mead. Fiber composition and digestibility were determined on leaf blade, leaf sheath, and stem fractions of the primary growth stages. Significant differences for theoretical true digestibility (TD) and neutral detergent fiber (NDF) existed for morphological components at each sward maturity. However, digestion characteristics of the sward components were not stable across primary growth stages. Rate of fiber digestion was faster for most sward components at Ames than Mead, although stems of elongating tillers from elongating swards digested faster on plants grown at Mead than Ames. Rate of fiber digestion of stems was typically slower than either leaf blades or sheaths, but in several instances they were similar or stems had faster rates of fiber digestion. Although phenotypic selection can increase fiber digestibility, plant maturity remains an important factor, and selections may require evaluation at different stages of morphological development. Thus, improvements in forage digestion, at least in switchgrass, may only be manifested for the growth stage at which it was selected.

Qualidade de silagens de híbridos de sorgo (Soghum bicolor (L.) Moench) de portes baixo, médio e alto com diferentes proporções de colmo+folhas/panícula: 1. Avaliação do processo fermentativo

O objetivo deste experimento foi avaliar a qualidade fermentativa de silagens de sorgo de portes baixo, médio e alto, com diferentes combinações de colmo+folhas/panícula (100:00, 80:20, 60:40, 40:60, 20:80 e 00:100), por meio de análises laboratoriais. A planta inteira foi utilizada como controle. Os híbridos foram cultivados e ensilados aos 104 dias de idade em silos de laboratório de PVC, com 10 cm de diâmetro e 40 cm de comprimento (três repetições por tratamento). Os silos foram abertos aos 56 dias após a ensilagem. Os teores de matéria seca (MS), carboidratos solúveis, nitrogênio amoniacal (N-NH3) e pH foram determinados. As diferenças foram verificadas por intermédio do teste SNK. Os valores de pH das silagens foram, em média, 3,79 e os teores de N-NH3/nitrogênio total foram inferiores a 8% em todos os tratamentos. Os teores de MS das silagens variaram de 19,40 a 49,40 %, mas todos os tratamentos conservaram-se bem de acordo com pH e N-NH3. As densidades dos silos foram maiores com o aumento da participação da panícula. Os valores de carboidratos solúveis do material original foram baixos para a maioria dos tratamentos, porém isto não prejudicou a fermentação da massa ensilada.

Amonização da quirera de milho com alta umidade

O objetivo deste trabalho foi verificar o efeito da amonização sobre teor de proteína bruta (PB), retenção de nitrogênio (RN), teor de matéria seca (MS), conservação, constituintes da parede celular e digestibilidade in vitro da matéria seca (DIVMS) da quirera de milho com alta umidade (25%). Quatro níveis de amônia anidra (0, 1, 2 e 3%) e cinco períodos de aeração (0, 7, 14, 21 e 28 dias) foram estudados em delineamento inteiramente ao acaso, em esquema de parcelas subdivididas. Os teores de PB da quirera aumentaram (10,3; 14; 15,2; e 16,2%) com os crescentes dos níveis amônia anidra (0, 1, 2 e 3%). A RN diminuiu, 61,9; 39; e 31,2%, para os níveis de 1, 2 e 3% de amônia anidra, respectivamente. O teor de MS reduziu com o aumento dos níveis de amônia anidra (81,0, 77,7, 77,0 e 78,0%) e dos períodos de aeração (74,2; 75,8; 78,9; 80,3; e 80,7%). A RN (52,2 para 38,9%) e os teores de PB (14,7 para 13,5%) diminuíram com o aumento do período de aeração, respectivamente, no período de 0 a 28 dias. Houve a presença de fungos para os níveis de 0 e 1% de amônia anidra, associados a temperaturas mais altas. Os teores de fibra em detergente acido (5,6%) e celulose (4,5%) permaneceram inalterados, tanto para os niveis de amônia anidra, quanto para períodos de aeração. Os teores de fibra em detergente neutro (22,7; 22,8; 18,5; e 14,8%) e hemicelulose (17,0; 17,3; 12,7 e 9,2%) reduziram para os níveis de 0, 1, 2 e 3 % de amônia anidra, respectivamente. A DIVMS (88,5; 89,8; 90,3; e 90,8 %) da quirera de milho melhorou com o aumento dos níveis de amônia anidra (0, 1, 2 e 3%).

Avaliação do valor nutritivo do bagaço de cana-de-açúcar amonizado com uréia

O trabalho foi desenvolvido objetivando-se avaliar o efeito da adição de uréia em doses crescentes, na presença ou ausência de urease, sobre o valor nutritivo do bagaço de cana-de-açúcar. O delineamento experimental foi inteiramente casualizado em arranjo fatorial (4 x 2) + 1 (controle), com quatro repetições. Os fatores avaliados foram níveis de uréia (2,0; 4,0; 6,0; e 8,0% da matéria seca), níveis de urease (presença, 20,0% da matéria fresca da uréia, e ausência) e um tratamento controle (0,0% de uréia e ausência de urease). Houve efeito da adição de uréia (63,3%) em relação ao controle (69,6%) e efeito da presença de urease (64,4%) em relação à sua ausência (62,1%), para o teor de matéria seca (MS). O menor teor de MS (62,5%) foi observado no nível de 6,2% de uréia. O teor de proteína bruta (PB) cresceu linearmente com a adição de uréia (12,0%) em relação ao controle (1,2%), sem urease. O teor de fibra em detergente neutro (FDN) dos materiais amonizados (81,4%) foi menor que o controle (84,7%), com efeito linear negativo das doses crescentes de uréia. Houve teores mais elevados de FDN nos tratamentos com presença de urease (82,1%) em relação aos tratamentos sem a mesma (80,8%). A digestibilidade in vitro da matéria seca (DIVMS) média do tratamento controle (23,2%) foi inferior à DIVMS média dos tratamentos com uréia (28,5%), com efeito linear positivo dos níveis crescentes de uréia. Não houve efeito da urease sobre a DIVMS do bagaço. A amonização com uréia melhorou o valor nutritivo do bagaço de cana-de-açúcar, sem a necessidade de adição de urease.

Yield and Forage Quality of Interseeded Legumes in a High-Desert Environment

ABSTRACT This study evaluates the forage yield and quality of legumes interseeded into sweet corn. Five legumes (‘Madison’ hairy vetch, ‘Parabinga’ barrel medic, ‘Nitro’ alfalfa, ‘Indianhead’ black lentil, and ‘Arlington’ red clover) were interseeded into sweet corn at last cultivation of the sweet corn in 1993 and 1994. Our objectives were to evaluate these legumes in terms of fall and spring dry-matter yield (DMY), crude protein concentration (CPC), crude protein yield (CPY), and in vitro dry matter disappearance (IVDMD). Corn ears and stover were harvested 31 August to 2 September 1993 and 16–17 August 1994. Crude protein concentration was generally higher for hairy vetch and alfalfa. Crude protein yield significantly increased from October to November in both years. November CPY was generally higher for barrel medic and hairy vetch. In April of both years, hairy vetch had the highest CPY among the overwintering legumes (hairy vetch, alfalfa, and red clover). Except for hairy vetch and red clover in trial year 2, mean IVDMD values were highest for the November sample dates.

Preference for Smooth Bromegrass Clones Is Affected by Divergent Selection for Nutritive Value

Selective grazing by sheep (Ovis aries) leads to diet improvement. To learn whether animals select the most nutritious food available, differences in percent consumption were determined among smooth bromegrass (Bromus inermis Leyss.) clones selected for divergent levels of neutral detergent fiber (NDF) or in vitro dry matter disappearance (IVDMD). High‐ and low‐NDF clones from a single population and high‐ and low‐IVDMD clones from four populations were evaluated as spaced plants in separate replicated trials. Preference was determined by offering sheep grazing access to complete blocks comprised of both high and low selections. Pre‐ and post‐grazing plant height and weight were measured and the differences used to calculate percent consumption, which was used as an indicator of preference. Preference and forage nutritive value were determined at three grazing periods in each of 2 yr. High‐IVDMD clones (mean IVDMD = 700 g kg−1) were 12% more preferred (29 vs. 26% of height consumed) than low‐IVDMD clones (mean IVDMD = 690 g kg−1). Low‐NDF clones (mean NDF = 470 g kg−1) were 36% more preferred (34 vs. 25% of height consumed) than high‐NDF clones (mean NDF = 505 g kg−1). Preference was positively correlated with IVDMD in three of four populations and negatively correlated with NDF. Sheep discriminated between equally‐accessible, more‐ and less‐nutritious clones and preferentially selected the more nutritious clones.

Winter annual small grain forage potential. II. Quantification of nutritive characteristics of four small grain species at six growth stages

Four small grain species, barley, oat, rye, and wheat were harvested at six growth stages to investigate their nutritive quality as a possible replacement for corn silage. Crude protein (CP), in vitro dry matter disappearance (IVDMD), neutral detergent fiber (NDF), acid detergent fiber (ADF) and lignin contents were measured on fresh and ensiled samples. The IVDMD, an estimate of forage ruminant digestibility, of all species generally decreased from the vegetative (765–854 g kg‐1) through the milk stage (505–662 g kg‐1) and then remained unchanged or increased slightly through hard dough with the exception of oats which often decreased during later stages of growth. The IVDMD of rye was usually lower than the other species from the milk to hard dough stage. The IVDMD of barley was generally higher than the other species at the soft and hard dough stages. The NDF, ADF, and lignin fractions usually increased from the vegetative to milk stages and remained unchanged or increased slightly through the hard dough stage. The ADF and lignin are negatively associated with forage digestibility while NDF values are negatively related to dry matter intake. The ADF of rye was generally higher than the other species at the milk and soft dough stages. Rye and barley contained more lignin than the other species from the heading through hard dough stage. Crude protein content generally decreased from the vegetative through milk stages and then leveled off or decreased slightly through the hard dough stage. Crude protein of oats was lower than other species at the vegetative stage, while rye generally contained more crude protein than the other species at the vegetative and boot stages. These data in combination with forage yield data reported in an associated paper suggest that small grains can offer a nutritious source of animal feed for farmers in the southeastern United States. Rye tended to stand out among the species at the early stages of growth (vegetative to boot) as a highly digestible green chop or grazing crop that is also high in protein. Barley and wheat stand out as excellent high yielding, nutritious silage choices at the soft dough stage.