Amount Of Corn Research Articles

Cultivation and dynamic cropping processes impart land-cover heterogeneity within agroecosystems: a metrics-based case study in the Yazoo-Mississippi Delta (USA)

ContextCultivation and crop rotation, influenced by federal policy, prices, and precipitation, are significant sources of land-cover heterogeneity. Characterization of heterogeneity is required to identify areas and trends of stability or change.ObjectivesWe analyzed a land-cover time series within a prominent agroecosystem in the US, the Yazoo-Mississippi Delta (the Delta), as a case study of which metrics capture dynamics of landscape composition, configuration, connectivity, and context.MethodsAn assessment of land cover- from 2008 to 2021- was conducted and analyzed for potential differences among three Farm Bill eras. Twelve out of 23 metrics (including three new ones presented herein) examined were useful in characterizing land-cover heterogeneity.ResultsAlthough there was no increase in cultivated land, > 72% of the Delta experienced changes in land-cover type, and ~ 3% of the Delta was stable monoculture. Configurational metrics varied across years for soybeans, cotton, and rice, indicating prevalence of field-level changes in composition; connectivity metrics revealed isolation of upland forest and rice. The amount of corn was positively associated with the previous year’s commodity prices and negatively with precipitation whereas soybean acreage was lower in high-precipitation years and more dependent on commodity prices. Farm Bill effects were mixed among categories, whereas CRP generally declined.ConclusionsThe Delta experienced land-cover change with no net loss or gain of cultivated lands. Using 12 metrics that captured temporal shifts in spatial patterns, we characterized this agroecosystem as a shifting mosaic. Our approach may be useful for identifying areas of spatio-temporal heterogeneity or stability, with implications on resource management.

Effects of weather and landscape use on mourning dove population trends in North Dakota

AbstractMourning dove (Zenaida macroura) populations are believed to be declining throughout much of the United States since widespread population surveys were implemented in the mid‐1960s. However, results from the Mourning Dove Call‐Count Survey and North American Breeding Bird Survey indicate no trend for mourning doves in North Dakota. In addition, little is known about how climate and landscape factors may influence trends in mourning dove populations, especially in the northern extent of their breeding range. We used late‐summer roadside counts conducted in North Dakota from 1970–2017 (n = 3,368), along with information from National Oceanic and Atmospheric Administration (NOAA) weather stations and the Census of Agriculture (United State Department of Agriculture) to develop generalized linear mixed models to analyze trends and identify weather and landscape variables that may be affecting mourning dove populations in North Dakota. Our results indicated that mourning doves counted along roadside transects have declined over the last 50 years in northcentral, northeast, and southeast regions of North Dakota where agriculture activity is most intensive and total cropland currently makes up at least 65% of the total landscape. Conversely, in northwest, southwest, and southcentral regions of North Dakota, where cropland makes up less than 50% of the landscape, we detected no trends in mourning doves counted during the same period. In our weather and landscape model, area of harvested corn and soybeans had a negative effect on mourning doves counted ( = −0.174, SE = 0.029, 95% CI = −0.232, −0.116), whereas area of woodland had a positive effect on mourning dove abundance ( = 0.137, SE = 0.053, 95% CI = 0.032, 0.241). In addition, we found no evidence that temperature or precipitation were influencing mourning dove populations in North Dakota. Woodland habitat steadily declined in North Dakota during our study period. Additionally, the amount of corn and soybeans planted throughout the state has increased rapidly over the last 20 years, which has decreased cropland diversity, and this pattern of land use change is likely reducing food and cover during the nesting season. To halt declining mourning dove populations in intensively farmed regions, managers should implement conservation programs and private land initiatives that aim to provide a more balanced mix of cropland, grassland, and woodland, with reductions in corn and soybean acres.

Effects of Energy Cane (Saccharum spp.) Juice on Corn Ethanol (Zea mays) Fermentation Efficiency: Integration towards a More Sustainable Production

Despite being considered renewable, corn (Zea mays) ethanol still generates much debate over the use of fossil fuels in its production and is considered less sustainable than sugarcane (Saccharum spp.) ethanol. In Brazil, corn ethanol is starting to be produced in the Center-West and is expected to increase with the RenovaBio, a promising policy for biofuels adoption. In this context, energy cane (Saccharum spp.) is a biomass crop with high yields that can provide bagasse to supply the energy demand of the corn ethanol industry and provide juice with about 10% sugar content. However, the effects of introducing its juice in the production process are unknown. For these reasons, the objective of this study was to assess the effects of adding energy cane juice in corn ethanol production. Energy cane juice brings several advantages: (i) It provides sugars that can reduce by almost 50% the amount of corn and enzymes used, (ii) reduces the amount of water needed for ethanol production, and (iii) increases significantly the fermentation efficiency from 86.4% to 90.8% by providing minerals that support yeast growth. Therefore, energy cane can be integrated into the corn ethanol production process, making the fermentation more efficient and the production systems more sustainable.

Comparison of soil and corn residue cutting performance of different discs used for vertical tillage

High amount of corn (Zea mays L.) residue left in the field interferes with seeding operations, which hinders the viability of conservation agriculture. Vertical tillage is a promising practice in dealing with heavy crop residue, but its effectiveness largely depends on the design and use of tillage machines. In this study, three vertical tillage discs with different shapes, namely notched, plain, and rippled, were tested in a soil bin at two different working depths, shallow (63.5 mm) and deep (127 mm). Corn residues were spread on top of the soil as surface residue. soil cutting forces, soil displacement, and residue mixing with soil, as well as residue cutting were measured. The results showed that the working depth had a stronger effect on the performance of discs as compared to the disc type. No difference in residue cutting was found between the treatments. The deep working depth resulted in 5.1% higher residue mixing, 53.4% greater soil cutting forces, and 34.9% larger soil displacements, as compared to the shallow depth. The rippled disc resulted in the largest soil displacements with the greatest demand in soil cutting forces. Overall, the rippled disc was the most aggressive among the three discs with regard to the performance indicators measured. The results suggested that varying working depth would be an effective approach in changing the soil dynamics and residue cutting performance of the discs for vertical tillage.

Effects of high-protein distillers dried grains on growth performance of nursery pigs.

A total of 300 pigs (DNA 400 × 200, Columbus, NE), initially 11.1 kg, were used in a study to evaluate the effects of increasing amounts of high-protein distillers dried grains (HP DDG) on growth performance and to estimate its energy value relative to corn. Pigs were weaned, placed in pens with five pigs each, and fed a common diet for 21 d after weaning. Then, pens were assigned to treatments in a randomized complete block design. There were 5 treatments with 12 replicates per treatment. Treatments consisted of 0, 10, 20, 30, or 40% HP DDG, formulated by changing only the amounts of corn and feed-grade amino acids. Pigs were weighed weekly for 21 d to evaluate average daily gain (ADG), average daily feed intake (ADFI), and gain-to-feed ratio (G:F). Caloric efficiency was obtained by multiplying ADFI by kcal of net energy (NE) per kg of diet and dividing by ADG. The NE values for corn and soybean meal were obtained from NRC (2012), and initial estimates for HP DDG NE were derived from the Noblet et al. (1994) equation. The energy of HP DDG was estimated based on caloric efficiency relative to the diet without HP DDG. Pigs fed diets with increasing HP DDG had a linear decrease (P < 0.01) in ADG, ADFI, and final body weight. There was a tendency for a quadratic response (P = 0.051) in G:F, with the greatest G:F observed for pigs fed diets with 40% HP DDG. There was a linear reduction (P < 0.05) in caloric efficiency with increasing amounts of HP DDG, indicating the initial NE estimate of HP DDG was underestimated. The use of caloric efficiency to estimate the energy value of HP DDG presents several limitations. This approach assumes that the NE values of corn and soybean meal are accurate and does not take into account possible changes in body composition, which can influence the G:F response as leaner pigs are more efficient. In conclusion, increasing HP DDG in the diet linearly decreased ADG and ADFI. Using caloric efficiency to estimate energy content relative to corn, the HP DDG used in this study was estimated to be 97.3% of the energy value of corn. Direct or indirect calorimetry is needed to confirm this value.

Texture of surimi-canned corn mixed gels with conventional water bath cooking and ohmic heating

The effect of moisture content in surimi–canned corn mixed gels (SCG) was measured using different heating methods (water bath heating (WBH) and ohmic heating (OH)). The degree of moisture migration of canned corn embedded in surimi with 5, 20, and 100% (corn alone) corn content was measured using image analysis and moisture content after cooking in a water bath (WB) (90 °C). To investigate the effects of water migration from canned corn on the SCG, the changes of textural properties of SCG prepared with WBH and OH were also studied. The amount of corn in the mixture was adjusted to 0, 5, 10, and 20% of the mixture. The modified hardness and modified cohesiveness of the mixture significantly decreased as the quantity of corn increased with both heating methods (P < 0.05). However, OH treated samples showed a smaller decrease in modified hardness and modified cohesiveness in comparison with WBH. The shear force of corn in the OH treated samples was higher than that cooked with WBH. There were no significant differences between the shear force of canned corn without heating and OH corn (P ≥ 0.05). The mixed gels with OH showed significantly lower moisture loss (%) after heating than with WBH. The moisture content in the canned corn was also affected by the heating method used and the migration of water from the canned corn had an important role in the texture properties of SCG.

High variability within pet foods prevents the identification of native species in pet cats' diets using isotopic evaluation.

Domestic cats preying on wildlife is a frequent conservation concern but typical approaches for assessing impacts rely on owner reports of prey returned home, which can be biased by inaccurate reporting or by cats consuming prey instead of bringing it home. Isotopes offer an alternative way to quantify broad differences in animal diets. By obtaining samples of pet food from cat owners we predicted that we would have high power to identify cats feeding on wild birds or mammals, given that pet food is thought to have higher C isotope values, due to the pervasive use of corn and/or corn by-products as food ingredients, than native prey. We worked with citizen scientists to quantify the isotopes of 202 cat hair samples and 239 pet food samples from the US and UK. We also characterized the isotopes of 11 likely native prey species from the southeastern US and used mixing models to assess the diet of 47 cats from the same region. Variation in C and N isotope values for cat food was very high, even within the same brand/flavor, suggesting that pet food manufacturers use a wide range of ingredients, and that these may change over time. Cat food and cat hair from the UK had lower C values than the US, presumably reflecting differences in the amount of corn used in the food chains of the two countries. This high variation in pet food reduced our ability to classify cats as hunters of native prey, such that only 43% of the animals could be confidently assigned. If feral or free ranging cats were considered, this uncertainty would be even higher as pet food types would be unknown. Our results question the general assumption that anthropogenic foods always have high C isotope values, because of the high variability we documented within one product type (cat food) and between countries (US vs. UK), and emphasize the need to test a variety of standards before making conclusions from isotope ecology studies.

PSIV-22 The effects of altering ruminal fermentable carbohydrate supply in finishing diets containing distillers grains on rumen fermentation characteristics and nitrogen utilization

Abstract This study examined the effects of altering ruminal fermentable carbohydrate (RFC) supply by feeding different amounts of corn and wheat in finishing cattle diets containing 15% corn dried distillers grains [DDGS; dry matter (DM) basis] on ruminal fermentation characteristics and nitrogen (N) utilization. Six ruminally-cannulated crossbred heifers were used in a replicated 3 × 3 Latin square design with 28 d periods. Dietary treatments were either corn (73% of diet DM; CON), 53:20 corn:wheat blend (20W) or 33:40 corn:wheat blend (40W) as the major fermentable carbohydrate source. Diets were isonitrogenous (12% CP; DM basis). Feed intake was measured daily. Indwelling pH logger were used to measure ruminal pH (d 22 to 28) and ruminal fluid was collected from d 26 to 28 to determine fermentation characteristics, as were feces and urine to measure N excretion. Data was analyzed using PROC MIXED in SAS. Dry matter and N intake tended to be lower (P ≤ 0.07) for heifers fed the 40W compared to the CON and 20W diets. There was no diet effect (P = 0.15) on total VFA concentration; however, the duration and area for pH &amp;lt; 5.5 tended to be longer (P = 0.07) and greater (P = 0.096), respectively, for heifers fed the 20W and 40W compared to the CON diet. There was no diet effect (P ≥ 0.44) on ruminal ammonia concentration and total urine N excretion (g and % of N intake). However, urine urea N (UUN) excretion as a percentage of total urine N tended to be lower (P = 0.05) in heifers fed the 20W and 40W compared to the CON diet. In summary, although altering RFC supply by feeding increasing amounts of wheat resulted in a decrease in UUN excretion, it also caused a decrease in ruminal pH that possibly compromised DM intake.

Effects of newly harvested corn on growth performance, intestine development and metabolism of nutrients in broilers

This experiment was to study the effects of newly harvested corn on growth performance, intestine development and metabolism of nutrients in broilers. A total of 380 one-day-old Arbor Acres male broilers were assigned to ageing corn group (AC group), 1/3 newly harvested corn group (1/3 NC group), 2/3 newly harvested corn group (2/3 NC group), and newly harvested corn group (NC group), which according to the proportion of newly harvested corn in the total amount of corn of basal diets. Each group included six replicates with 16 birds. Digestion and metabolism trials were conducted at 39 to 42 days of age. Results showed that feed: gain ratio (F/G) of NC group was higher than that of 1/3 NC group and 2/3 NC group at 22 to 42 and 1 to 42 days of age (p < .05). The metabolic rates of calcium and phosphorus in NC group were lower than those in AC group, 1/3 NC group and 2/3 NC group (p < .05). In NC group, the relative weight of caecum was significantly higher than that in 2/3 NC group and AC group at 21 days of age (p < .05), while the relative weight of jejunum was lower than that in 2/3 NC group and AC group at 42 days of age (p < .05). In summary, newly harvested corn can reduce the growth performance and metabolism of some nutrients in broilers. Newly harvested corn should be controlled during actual production.HighlightsNewly harvested corn can reduce the growth performance in broilers.Newly harvested corn can reduce apparent metabolic rate of calcium and phosphorus in broilers.Newly harvested corn can affect the intestine development in broilers.

Statistical analysis of corn consumption for improved mycotoxin exposure estimates for the population of Veracruz City, Mexico

ABSTRACTCorn consumption was evaluated in the population of Veracruz City, Mexico, through two different dietary intake questionnaires. The selection of 300 sampling locations was completely random. The population was segregated into gender and age categories. A daily consumption questionnaire was used to determine the consumption of corn tortillas and a frequency questionnaire to determine the consumption of other corn products. A book of photographs was used to adjust criteria on the size of the portions of corn products and a probability distribution was built of the weight and content of corn for tortillas. Probability density functions (PDFs) were used to describe the consumption of each corn product. Men and those between 14 and 65 years old have the highest consumption of tortillas. Tortillas, antojitos, tacos and chilaquiles are the products that provide the largest amount of corn to the Veracruz people’s diet. Even though these products are nixtamalisated, there is evidence that after a thermo-alkaline process some contaminants such as mycotoxins (like aflatoxin, which is a mutagenic, teratogenic and carcinogenic toxin) could be present in high concentrations. These results highlight the need to characterise the consumption of one of the main foods included in dietary staple in Mexico as a first step for a probabilistic risk assessment.

Nutritive Value of Sunflower Silages Ensiled with Corn or Alfalfa at Different Rate

Sunflower (Helianthus annuus L.) having shorter growing season, better cold tolerant and more drought resistant is important alternative silage plant in highlands. But it has poor silage quality. To improve the quality of sunflower silage can be mixed an appropriate amount of corn (Zea mays L.) and alfalfa (Medicago sativa L.). This research was carried out to evaluate quality characteristics of nine silage types: Sunflower, corn and alfalfa silages; plus their some mixtures silages (75% sunflower + 25% corn, 50% sunflower + 50% corn, 25% sunflower + 75% corn, 75% sunflower + 25% alfalfa, 50% sunflower + 50% alfalfa and 25% sunflower + 75% alfalfa); at two harvest stages: Beginning of flowering for sunflower and alfalfa and milk-dough stage for corn (early stage), and end of flowering stage for sunflower and alfalfa, and dough stage for corn (late stage). The experimental design was in a factorial arrangement of randomized complete block with replicated four times. Dry matter content (DM), crude protein content (CP), neutral detergent fiber content (NDF), acid detergent fiber content (ADF), silage pH and physical characteristics (PC) of silages were determined in this study. Mixing of alfalfa in NDF, ADF and CP and corn in DM, pH and PC had positively effect in sunflower silages. Late stage had positively affected DM, PC and pH for silage. Consequently, sunflower silages mixed with corn, with the condition of not being less than 50% at late stage, are recommended for farmers. Keywords: Sunflower; Corn; Alfalfa; Mixtures; Silage

Effect of high oil corn in the diets of Nellore steers on growth performance, carcass characteristics, meat quality, and longissimus muscle fatty acid profile

The objective in this study was to evaluate the effects of substituting high oil corn (HOC) for typical corn (TC) on performance, carcass characteristics, meat quality, and longissimus muscle (LM) fatty acid profile of Nellore steers fed diets containing different amounts of corn. Forty-eight individually fed Nellore steers (441±32kg initial body weight) were allocated by body weight to four pens equipped with electronic gates in a randomized complete block design with six treatments in a 2×3 factorial arrangement of treatments, with two corn types (CT) and three corn levels (CL). Treatments consisted of diets containing 25, 40, or 55% TC or HOC on a dry matter (DM) basis. Animals were confined for 84 days so that DM intake and average daily gain (ADG) were measured individually. After the feedlot period, animals were slaughtered at a commercial slaughterhouse, carcass characteristics were evaluated, and LM samples were collected for further analyses of meat quality and fatty acid profile. Statistical analyses were conducted using the MIXED procedure of SAS. No differences among CL and CT were observed for DM intake, metabolizable energy intake, gain to feed ratio, and dietary net energy for maintenance and gain. Steers receiving HOC had greater ADG in comparison with those fed TC when CL was 25%, but no differences were observed when CL was 40 or 55%. Cooking loss and LM redness were linearly decreased (P≤0.05) with the increasing CL. No effects of CL and CT were observed for any other carcass characteristics and meat quality variables. The LM proportions of stearic, linolenic, and total omega-6 fatty acids, as well as omega-6 to omega-3 fatty acids ratio (n-6:n-3), were linearly increased (P≤0.04) as CL increased, whereas conjugated linoleic acid (CLA) proportions showed a quadratic response (P<0.01) to corn inclusion, with lower values observed for steers fed 40% corn. Longissimus muscle proportions of myristic and palmitic acids were decreased (P≤0.02), whereas proportions of CLA, total omega-6, and total polyunsaturated fatty acids, as well as n-6:n-3, were increased (P≤0.04) when TC was replaced with HOC. In conclusion, replacing TC with HOC in the diets of Nellore steers fed different corn levels had no effects on animal performance, carcass characteristics, and meat quality, but improved LM fatty acid profile, which suggests that the produced beef might be healthier for consumers.

Determining of the Effect of Lysine:calorie Ratio on Growth Performance and Blood Urea Nitrogen of Growing Barrows and Gilts in Hot Season and Cool Season in a Commercial Environment.

Two experiments were conducted to determine an optimum Lys:calorie ratio (g of total dietary Lys/Mcal of DE) for growing barrows and gilts in cool and hot seasons in a commercial environment. In Exp. 1, 96 barrows and 96 gilts were randomly allocated in 1 of 4 dietary treatments (2.7, 3.0, 3.3, 3.6 g of Lys/Mcal of DE). Each treatment had 12 replicate pens with 4 pigs per pen. The experiment lasted for 34 d in the cool season (March 12th to April 15th). Diets were based on corn-wheat-soybean meal. Lys:calorie ratio were attained by adjusting the amount of corn and soybean and supplementation of crystalline Lys. Total Lys intake and available Lys intake were increased (p<.05) as dietary Lys:calorie ratio increased. The BUN concentration on d 34 for barrows, and BUN change for barrows and gilts linearly increased (p<0.05) in response to increasing dietary Lys:calorie ratio. For gilts, back fat was decreased and then increased (Quadratically, p<0.05) as increasing dietary lys:calorie ratio. Exp. 2 had a similar design as Exp. 1 with the exception that Exp. 2 was conducted in hot season (June 30th to September 11th) for 42 d. Diet of Exp. 2 was the same as Exp. 1. Total Lys intake and available Lys intake increased (p<0.05) as dietary Lys:calorie increased. On d 42, the BUN concentration increased (p<0.05) in response to the increasing dietary Lys:calorie ratio. In conclusion, dietary Lys:calorie ratio of 2.7 g of Lys/Mcal of DE could satisfy the requirement of 25 to 50 kg growing pigs. Increasing dietary Lys:calorie ratio could increase BUN concentration in growing pigs.

Assessing the Impact of Corn-Ethanol Production on Global Corn Price Based on a VAR Model

The fuel ethanol industry has been in rapid development in recent years with the US as a leading force, which consumes large amount of corn. In order to assess the impact of corn-ethanol production on global corn price, a VAR model is used in this paper. By impulse responses analysis and variance decomposition analysis the direct impact of corn-ethanol production on global corn price and its relative importance compared with other external factors are proved. The results show that increasing amount of corn used for US ethanol production leads to rapid increases of global corn price when the corn production is steady. The proportion of corn used for ethanol production among total corn production in the US plays an important role in affecting global corn price among all external factors, and the significance of its impact will enhance in the long run. The fuel ethanol industry should turn to non-grain materials in the future to keep the global corn price steady and guarantee global food security, and it’s necessary for all fuel ethanol producers to take action.

The nutritive value of extruded corn in nutrition of broiler chickens

In poultry farming is increasing effort to increasing profitability and decreasing of feed cost. Behind the components that are part of the mixture, the most of cost makes processing of nutrients. Extrusion is process which is increasingly used in order to enhance the quality of different feed for poultry. The aim of this research was comparative testing of nutritional value of extruded and nonextruded corn in nutrition of broiler chicken. The experiment was conducted under experimental growing conditions, in duration of 42 days. The following parameters were measured: growth, feed intake and vitality of broilers. The experiment was divided into two groups of chickens hybrid Ross-308, which were grown separately by sex with 8 replication. The first group was fed standard pelleted mixtures for growing chickens, in which the entire amount of corn in the mixture was extruded, and the second, control group was fed the same food in which corn was not extruded. In the second week of rearing the body weight was 437 g in both groups. In 4th week of age the average body weight was 1439g in group I, and 1419 in group II. For the first group conversion was 1,69 and for the second it was 1,71. The final body weight amounted 2595g for the first group and 2609 for the control group. In the first group conversion was 1,91, mortality 4,39% and the production index had a value of 309, and in the second 1,92; 4,56% and 306. In this study excellent production effects were achieved, so it was not expected that extrusion could achieve better production effects. These results showed that extrusion process does not always give the expected effects.

Effect of supplementation of dried distillers grains with solubles on forage intake and characteristics of digestion of beef heifers grazing small-grain pasture1

Sixteen ruminally cannulated, English-crossbred heifers (378 ± 28.4 kg) grazing small-grain pasture (SGP) were used in a completely randomized design to evaluate effects of supplementing different amounts of corn dried distillers grains with solubles (DDGS; 0, 0.2, 0.4, and 0.6% of BW; as-fed basis) on forage intake, digestibility, and rumen fermentation characteristics. The experiment was conducted from April 6 through April 20, 2007. Heifers grazed in a single SGP with supplements offered individually, once daily at 0700 h. Forage and total OM, CP, and NDF intake were not affected (P ≥ 0.21) by DDGS amount. Digestibility of NDF and ether extract (EE) increased linearly (P < 0.001) when heifers consumed more DDGS. Intake of DM (kg/d and g/kg of BW), ruminal volume (L), fluid dilution rate (%/h), fluid flow rate (L/h) turnover time (h), and particle dilution rate (SGP and DDGS) were not affected (P ≥ 0.32) by increasing DDGS supplementation amount. In situ DDGS CP kinetic parameters were not affected (P ≥ 0.25) by increasing DDGS supplementation amount. Forage masticate in situ soluble CP fraction and CP effective degradability increased quadratically (P = 0.01) with increasing DDGS supplementation amount. However, amount of DDGS did not affect forage masticate CP slowly degradable fraction (%; P = 0.39) or degradation rate (%/h; P = 0.63). Rate of in situ disappearance (%/h) for DDGS DM (P = 0.94), forage masticate DM (P = 0.89), and NDF (P = 0.89) were not affected by DDGS supplementation amount, nor was rumen undegradable intake protein (% of CP) for DDGS (P = 0.28) and forage masticate samples (P = 0.93). Ruminal concentration of VFA and ammonia and ruminal pH were not affected (P ≥ 0.21) by increasing DDGS amount. Results indicated that DDGS can be used in SGP supplements without negatively affecting forage intake, digestibility, or ruminal fermentation.

Utilização do nitrogênio da palha de milho e de adubos verdes pela cultura do milho

A qualidade dos resíduos vegetais de culturas comerciais e adubos verdes influencia a taxa de mineralização/imobilização de N e o respectivo aproveitamento desse nutriente pelas subseqüentes culturas. Com o objetivo de avaliar a utilização do N mineralizado da parte aérea e do sistema radicular da crotalária (Crotalaria juncea) e milheto (Pennisetum americanum) e da palha de milho, marcados com 15N, realizou-se um estudo, em casa de vegetação, no Centro de Energia Nuclear na Agricultura - CENA/USP, Piracicaba (SP), em vasos com 5 kg de solo de um Latossolo Vermelho distroférrico. Foram utilizados seis tratamentos e quatro repetições, dispostos num delineamento inteiramente casualizado, compreendendo: T1 = palha de milho-15N (parte aérea, exceto os grãos) (80 mg kg-1 de N no solo); T2 = raiz de milheto-15N (30 mg kg-1 de N no solo); T3 = parte aérea de milheto-15N (80 mg kg-1 de N no solo); T4 = raiz de crotalária-15N (30 mg kg-1 de N no solo); T5 = parte aérea de crotalária-15N (80 mg kg-1 de N no solo) e T6 = tratamento sem adição de fonte orgânica de N. Para os tratamentos que receberam raiz marcada com 15N, adicionou-se parte aérea sem marcação isotópica na mesma quantidade que naqueles que receberam parte aérea marcada, e vice-versa. As raízes foram incorporadas ao solo e a parte aérea adicionada sobre a superfície. Para avaliar absorção de N da palha de milho-15N (7,35 Mg ha-1, equivalente a 56 kg ha-1 de N) pela cultura do milho, realizou-se também um experimento de campo, na mesma área em que foi coletado solo para o experimento de casa de vegetação. A quantidade de N no milho proveniente da crotalária (111,80 mg vaso-1 N ) foi superior à do milheto (30,98 mg vaso-1 N ), que foi superior à da palha de milho (11,80 mg vaso-1N ). A crotalária proporcionou maior absorção de N e produtividade de matéria seca ao milho. O aproveitamento pelo milho do N da parte aérea da crotalária foi superior ao do N do sistema radicular, mas não houve diferença para o N do milheto. A absorção do N dos restos culturais de milho pela cultura do milho, no campo, foi de 4,1 % da quantidade inicial.

Exigência de lisina digestível para suínos machos castrados de alto potencial genético para deposição de carne magra na carcaça dos 15 aos 30 kg

Foram utilizados 50 suínos machos castrados (15,4 ± 1,02 kg PV inicial), com alto potencial genético para deposição de carne magra na carcaça, para determinação da exigência de lisina digestível, considerando o desempenho e a taxa de deposição de proteína na carcaça. Adotou-se o delineamento de blocos ao acaso, com cinco tratamentos, cinco repetições e dois animais por repetição. Os tratamentos consistiram de cinco níveis de lisina digestível (0,80; 0,90; 1,00; 1,10 e 1,20%), obtidos por meio da proporção de milho e farelo de soja nas rações. Os animais foram mantidos no experimento até atingirem 30,0 ± 1,93 kg PV. O ganho de peso diário foi influenciado de forma quadrática pelos níveis de lisina digestível, aumentando até o nível estimado de 1,10%. Observou-se efeito linear dos níveis de lisina digestível da ração sobre a conversão alimentar, a deposição de proteína e o consumo de lisina diário. O consumo de ração diário não foi influenciado pelo nível de lisina das rações. A exigência de lisina digestível para suínos machos castrados de alto potencial genético para deposição de carne magra na carcaça 15 a 30 kg é de 1,10%, que corresponde a um consumo de lisina digestível diário de 12,05 g.

Níveis de proteína bruta na dieta e desempenho reprodutivo de fêmeas primíparas em gestação

Foram testados três tratamentos (10,0; 13,5 e 17,0% de PB) com o objetivo de avaliar o efeito dos níveis de proteína bruta na dieta sobre o desempenho eprodutivo de 36 fêmeas (12 por tratamento) suínas primíparas em gestação. As dietas continham (ou excediam) todos os nutrientes necessários para suprir as exigências dos animais, de acordo com o NRC (1998), à exceção dos níveis de proteína bruta. Embora a proteína tenha sido diluída com amido, a proporção aminoacídica foi mantida em todas as rações, em razão da relação constante nas quantidades de milho e farelo de soja. Foram avaliados o ganho de peso da fêmea durante a gestação, o número de leitões nascidos, o peso da leitegada, a espessura de toucinho e o desempenho da matriz durante a lactação e após o desmame. Não foram observadas diferenças significativas entre as médias das variáveis ganho de peso durante a gestação, espessura de toucinho, peso do leitão ao nascimento e número de leitões nascidos. Durante a lactação, não houve diferença entre os grupos de fêmeas alimentadas com níveis diferentes de proteína bruta na gestação para as variáveis consumo de ração, perda de peso, perda de espessura de toucinho, ganho diário de peso dos leitões e peso da leitegada ao desmame. Não houve efeito dos tratamentos no intervalo desmame-cio nos desempenhos reprodutivo e produtivo de fêmeas primíparas.

Effect of Amino Acids and Peptides on Mixing and Frozen Dough Properties of Wheat Flour

ABSTRACTFree amino acids, peptides, and vital wheat gluten were investigated to determine their effect on the mixing and frozen dough baking properties of wheat flour. Addition of 1% cysteine and aspartic acid decreased and glutamic acid, histidine, arginine, and lysine increased the mixing tolerance of flour. Cystine, methionine, tryptophan, and phenylalanine increased but isoleucine, histidine, glycine, arginine, glutamic acid, aspartic acid, and lysine decreased loaf volume of nonfrozen dough breads. However cystine, methionine, tryptophan, and phenylalanine did not increase loaf volume of bread prepared from frozen dough. Vital wheat gluten increased mixing tolerance and bread loaf volume only for the nonfrozen dough. However, wheat gluten hydrolysate, corn, and bonito peptides decreased mixing tolerance after optimum mixing time and were effective in increasing loaf volume for both frozen and nonfrozen dough. As the amount of corn and bonito peptide increased, specific loaf volumes also increased. Addition of 2.5% corn peptide was most effective in increasing loaf volume of frozen dough bread. Crust browning and crumb stickiness increased, whereas crumb softness decreased with addition of peptides. Addition of less than 1% peptide did not adversely affect the aftertaste and off‐flavor of bread. These results suggest that addition of peptides are effective for improving the baking quality of frozen dough, whereas amino acids and gluten have no effect.