Quadratic Effect Of Treatments Research Articles

Doses of orange (Citrus sinensis) essential oil for Nellore steers fed with a forage-based diet

The aim was to evaluate whether the doses of orange essential oil supplementation impact on dry matter intake (DMI), ruminal fermentation parameters, apparent nutrient digestibility, and methane production in Nellore steers fed with forage-based diet. A total of 32 rumen-cannulated Nellore steers (initial BW= 335±25 kg; age= 20±1 month) were assigned to individual pens in a randomized complete block design. Within block, steers were randomly assigned to treatments: CON= diet without orange essential oil (EO); 100EO= CON diet plus 100 mg orange EO/kg DM diet; 200EO= CON diet plus 200 mg orange EO/kg DM diet; and 500EO= CON diet plus 500 mg orange EO/kg DM diet. The main active compounds of the orange EO used were limonene (88.0 %) and myrcene (5.79 %). The experimental period lasted 28d, with 22d for adaptation and 6d for sample collection. From d23 to 27, samples of haylage, concentrate, and total fecal production were collected to determine the total tract apparent nutrient digestibility. Ruminal fluid was obtained from d28 at 0, 6, and 12 h after feeding to determine ruminal fermentation parameters and methane production. The difference was considered significant when P ≤ 0.05. No treatment effects were detected (P>0.05) to DMI or specific nutrient intake. The increasing levels of EO did not affect (P>0.05) the total apparent nutrient digestibility. No treatment effects were detected (P>0.05) for ruminal fermentation parameters in vivo. In ex situ, there was a treatment effect for acetate, total short-chain fatty acids (SCFA), methane, and relative energy loss (REL). For acetate, an increasing linear effect was observed for treatments that received EO for the variables production (g/kg) (P = 0.002) and gross energy (MJ/kg) (P = 0.002), with a higher concentration for the 500EO. For the total production of SCFA, there was an increasing linear effect of treatment with a higher concentration for 500EO for the variables production (g/kg) (P = 0.001) and gross energy (MJ/kg) (P = 0.001). For methane, a quadratic treatment effect was observed for the variables production (g/kg) (P = 0.045) and gross energy (MJ/kg) (P = 0.046), with lower concentrations for the 200EO. There was a decreasing linear treatment effect for REL(%) (P<0.001). The results for the use of orange EO as a manipulator of ruminal fermentation were promising and the dose of 500 mg/kg of DM showed a greater capacity to increase the energy efficiency of fermentation, with greater production of acids and lower production of methane, without affecting the voluntary intake of steers.

Doses of lemongrass (Cymbopogon citratus) essential oil for Nellore steers fed with a forage-based diet

The aim was to evaluate whether doses of lemongrass essential oil supplementation affect DMI, apparent nutrient digestibility and methane production in Nellore steers fed forage-based diets. According to their initial fasting BW, 32 Nellore steers (BW = 332±19 kg; age = 19±1 months) rumen cannulated and castrated, were allocated in individual pens in a randomized complete block design. The treatments were randomly assigned to the animals: CON= forage-based diet without addition of lemongrass EO; 200EO= CON diet plus 200 mg/kg lemongrass EO; 400EO= CON diet plus 400 mg/kg lemongrass EO; or 600EO= CON diet plus 600 mg/kg lemongrass EO. The experimental diets contained 95% Tifton-85 haylage and 5% ground corn. The experimental period lasted 21 days, 15 days for diet adaptation and 6 days for sample collection. Samples of haylage, concentrate and total feces production were collected from day 15 to 20, to determine the total apparent digestibility of nutrients. On the 21st day at 0, 6 and 12 h after feeding, rumen fluid was collected to determine the parameters of rumen fermentation and methane production. Significant effects were adopted when P ≤ 0.05. The main active compounds of the EO of lemongrass used were geranial (42.5%) and neral (30.49%). No treatment effects were detected for DM and nutrient intake. The increasing EO levels of lemongrass did not affect the apparent digestibility of nutrients. There was an increasing linear effect (P < 0.05) of treatment in the in vivo analysis, where the highest dose had the highest valerate concentration. There was no effect for any other variables in vivo. Effects on fermentation parameters were identified in the ex situ technique. For acetate, there was a quadratic treatment effect with higher values for the 400EO for the variable production (g/kg day; P = 0.02) and gross energy (Mcal/kg day; P = 0.02). There was linear increase for butyrate production (g/kg day; P = 0.04) and gross energy (Mcal/kg day; P = 0.04). There was a quadratic effect with higher values for the 400EO for production (g/kg day; P = 0.02) and gross energy (Mcal/kg day; P = 0.02) of SCFA. There was a quadratic effect for REL (P = 0.01), with lower loss in the 400EO. There was no treatment effect for propionate (P ≥ 0.97) and methane production (P ≥ 0.19). In conclusion, 400 mg/kg lemongrass EO optimized ruminal fermentation, minimizing energy loss due to methane emissions.

Fermentation dynamics, nutritional quality, and heating capacity of mixed silages of elephant grass (Pennisetum purpureum Schum) and Leucaena (Leucaena leucocephala)

Leucaena has been used to make mixed silages to obtain nutritional enrichment of the silages. Thus, the inclusion of Leucaena as an additive in mixed elephant grass silages can reduce fermentation losses, and increase the nutritional value and aerobic stability of the mixed silage without changing the fermentation profile. This study evaluated the fermentation profile, nutritional composition, and aerobic stability of elephant grass silages combined with different levels of Leucaena. A total of five inclusion levels of Leucaena (0, 20, 40, 60, and 80% on a dry matter basis) were added to elephant grass silages. A completely randomized design was adopted, with 5 treatments and 3 repetitions, totaling 15 experimental silos that were opened after 30 days of sealing. Fermentation profile, chemical composition, and aerobic stability were analyzed. A descriptive analysis of temperature and pH peaks during aerobic stability was performed. The increase in the inclusion of Leucaena in the composition of silages reduced gas and effluent losses, neutral and acid detergent fiber, cellulose, lignin, total and fiber carbohydrates, and total digestible nutrients, and resulted in increased dry matter, ether extract, and crude protein. A quadratic effect of treatments was found for the temperature to reach the maximum pH (P=0.009). Aerobic stability remained constant after 40% Leucaena inclusion in the composition of elephant grass silages. The inclusion of Leucaena up to 80% in the composition of elephant grass silages reduces fermentation losses, promotes a nutritional increase, and increases the aerobic stability of the silages.

Effects of Autolyzed Yeast Supplementation in a High-Starch Diet on Rumen Health, Apparent Digestibility, and Production Variables of Lactating Holstein Cows.

Simple SummaryFeeding high-starch (HS) diets has negative implications on the ruminal health and milk production of dairy cattle. Autolyzed yeast (AY) supplementation may alleviate the negative effects of an HS diet fed to dairy cows. Therefore, the objectives of this study were to determine the effects of the supplementation of commercially available AY in HS diets on lactation performance, rumen pH, N utilization, apparent digestibility (AD), and blood metabolites in lactating Holstein cows. This study postulated that AY supplementation may improve the rumen environment (rumen pH and AD) when feeding HS diets, thus improving lactation performance and altering blood metabolites.Fifteen multiparous rumen-cannulated Holstein cows were assigned to one of five treatments in a replicated 5 × 5 Latin square design. The treatments were low-starch (LS) (22.8 ± 1% of dry matter; DM) without autolyzed yeast (AY; LS0, control), high-starch (HS) (31.2 ± 4% of DM) without AY (HS0), and HS with either 15 g (HS15), 30 g (HS30), or 45 g (HS45) of AY supplementation. Cows in HS0 had increased (p < 0.03) dry matter intake (DMI; 24.9 kg/d) and energy-corrected milk (ECM; 34.4 kg/d) compared to cows in LS0 (19.9 and 31.3 kg/d, respectively). There was a tendency for a quadratic treatment effect for feed efficiency (ECM/DMI, p = 0.07) and crude protein (CP) apparent digestibility (AD) (p = 0.09). Cows in HS45 tended (p = 0.09) to have increased DMI (25.6 kg/d) compared to cows in HS0 (24.9 kg/d). Cows in HS0 had greater (p < 0.04) milk protein nitrogen (N; 166 g/d) and microbial N production (161 g/d) than those in LS0 (140 and 138 g/d, respectively). In conclusion, the addition of AY tended to improve DMI, feed efficiency, and CP AD when cows were fed the HS diet.

PSXIV-27 Use of narasin in diets for lactating ewes

Abstract The objective of this study was to define the ideal level of narasin to be used in diets for lactating ewes. Forty Dorper vs. Santa Inês ewes (53.6 ± 9.6 kg BW and 14 d in milk) were penned individually and used in a complete randomized block design. Ewes were fed a basal diet (16.77 ± 0.35% CP) containing 50% concentrate and 50% coastcross hay. The treatments were: 0N - control diet; 13N - 13 mg of narasin/kg of DM; 20N - 20 mg of narasin/kg of DM; 27N - 27 mg of narasin/kg of DM. Ewes were fed the diets from the wk 2 to 10 of lactation. Milk production was determined every 7 d during the experiment. Ewes were separated from lambs and mechanically milked for emptying of the mammary gland. After 3 hours, using the same procedure, milk production was recorded and samples collected for milk composition analysis. For DMI, there was a quadratic effect of treatments (0N=2.417; 13N=2.491; 20N=2.334; 27N=2.078 kg/d; P = 0.02). The milk production (g/3h) presented a quadratic response to levels of narasin (0N=186.37; 13N=194.91; 20N=194.01; 27N=164.49 g/3h; P = 0.03). In the milk composition, there was a linear reduction in the content of protein (0N=5.31; 13N=5.13; 20N=4.94; 27N=5.00%; P = 0.01) and ESD (0N=11.22; 13N=11.15; 20N=10.84; 27N=10.98 %; P = 0.03). However, the contents of fat, lactose and total solids were not affected by the treatments. As a consequence, the productions (g/3 hours) of fat, lactose and total solids were not affected by the diets. A quadratic response was observed for the productions (g/3 h) of protein (0N=9.86; 13N=9.76; 20N=9.52; 27N=8.29; P = 0.04) and ESD (0N=20.73; 13N=21.45; 20N=21.18; 27N=18.28; P = 0.03). In conclusion, 13 mg/kg of DM is the best concentration of narasin to be used in diets for ewes, values higher than this can compromise milk production and composition.

Improvements of in situ degradability of grass hay, wet brewer’s grains, and soybean meal with addition of clay in the diet of Holstein cows

Clay-based feed additives have been widely examined as tools for combating the negative impacts of both aflatoxin (AF) infected feedstuffs as well as subacute ruminal acidosis (SARA). The objective of this study was to determine the ruminal degradability of feedstuffs in response to 3 concentrations of dietary clay in lactating dairy cows. Treatments were: no clay (CON), 10, or 20 g/kg of dietary DM as clay (EcoMix®, UMG, Ukraine). Samples (8 g) of dried alfalfa hay (AH), grass hay (GH), wet brewer’s grains (WBG), ground corn (GC), corn silage (CS), or soybean meal (SBM) were placed into polyester bags (3 replicates per feed) and incubated for 0, 2, 4, 8, 12, 48, 72, or 96 h in 3 rumen-cannulated cows fed one of three treatments. Recovered bags were analyzed for DM, aNDF, ADF, starch, CP for all feedstuffs, and total fatty acids (TFA), saturated fatty acids (SFA), monounsaturated fatty acids (MUFA), and polyunsaturated fatty acids (PUFA) for GH, WBG, and CS. Soluble (S), digestible (D), and undigested (U) fractions; and fractional rate of digestion (Kd) and effective degradability (ED), were estimated for each feedstuff, treatment, and cow combination. Statistical analysis was preformed using the MIXED procedure of SAS. Grass hay S of DM exhibited a quadratic treatment effect (CON = 1.4, 10 g/kg = 1.7, and 20 g/kg = 1.2 g/kg). There was an increase in WBG D of DM as concentration of clay in the diet increased (CON = 5.9, 10 g/kg = 6.6, and 20 g/kg = 7.6 g/kg). There was a quadratic treatment effect for DM S (CON = 2.6, 10 g/kg = 3.4, and 20 g/kg = 1.5 g/kg) and ED (CON = 4.8, 10 g/kg = 5.7, and 20 g/kg = 3.9 g/kg) of SBM. There was a decrease in SBM S of starch (CON = 6.3, 10 g/kg = 4.7, and 20 g/kg = 3.3 g/kg) and an increase in SBM D of starch (CON = 7.7, 10 g/kg = 7.7, and 20 g/kg = 8.2 g/kg) as concentration of clay in the diet increased. There was an increase in GH D of SFA (CON = 3.4, 10 g/kg = 7.8, and 20 g/kg = 9.1 g/kg DM) and a decrease in both GH U (CON = 6.0, 10 g/kg = 1.9, and 20 g/kg = 0.0 g/kg DM) and Kd (CON = 0.07, 10 g/kg = 0.03, and 20 g/kg =0.01 h−1) of SFA as concentration of clay in the diet increased. There was a decrease in WBG S of SFA as concentration of clay in the diet increased (CON = 0.8, 10 g/kg = 0.4, and 20 g/kg = 0.3 g/kg). Corn silage D of TFA exhibited a quadratic treatment effect (CON = 7.3, 10 g/kg = 3.3, and 20 g/kg = 4.5 g/kg). In conclusion, the addition of clay at 10 g/kg of total dietary DMI maximized S for GH and SBM DM as well as ED for SBM. Also, the addition of clay at 20 g/kg of total dietary DMI maximized degradability of SFA for GH.

Physiological responses to a yeast and clay-based adsorbent during an aflatoxin challenge in Holstein cows

The objective of this study was to determine the effects of 2 different adsorbents (AD) composed of yeast fractions and bentonite (AD1 and AD2) during an aflatoxin (AF) challenge on the health and performance of lactating dairy cows. Lactating Holstein cows [(n=76); BW (mean±SD)=698±72kg; DIM=153±83 d] were assigned to 1 of 5 treatments in a randomized complete block design. The trial lasted 28 d and measurements were made from d 22 to 28. From d 22 to 24 cows received an AF challenge (100μg of AFB1/kg of diet DM administered orally). Treatments were: control (CON), no AD or AF; positive control (POS), no AD plus AF challenge; 30g per cow per day of AD1 and AF challenge (P30); 60g per cow per day of AD1 and AF challenge (P60); and 60g per cow per day of AD2 and AF challenge (PROT). The appearance and disappearance of AF excreted in milk was tested at each milking from d 22 to 28 using SNAP tests (SNP; IDEXX, Inc.). Blood was sampled on d 22 and 26 (n=2 per cow), and analyzed for superoxide dismutase (SOD) concentration. Milk samples from d 22 to 26 were analyzed for AFM1 concentrations by HPLC. Fecal samples collected from the rectum on d 22 and 24 were analyzed for AFB1 concentrations via HPLC. Statistical analysis was performed using the MIXED procedure of SAS. A quadratic treatment effect (P<0.001) was observed for plasma SOD concentrations at 2.77, 1.99, and 1.97±0.05U/mL for POS, AD30, and AD60 treatments, respectively. Aflatoxin M1 transfer (11.4 and 0.00±1.60g/kg), excretion (29.52 and 0.00±4.58μg/d), and concentrations in milk (0.76 and 0.00±0.16μg/kg) were greater for POS than CON, respectively (P<0.001) but no differences were observed among other treatments. A tendency for a quadratic treatment effect (P=0.08) was observed for fecal AFB1 concentrations at 6.78, 8.55, and 5.07±1.17μg/kg for the POS, P30, and P60 treatments, respectively. Oral supplementation of yeast and bentonite clay-based adsorbents during an AF challenge resulted in quadratic changes in plasma SOD and fecal AFB1 concentrations; however, no differences were observed for DMI or milk yield. In conclusion, yeast cell wall and bentonite-based adsorbent may be beneficial in reducing inflammation during an AF challenge but there were no treatment differences regarding its adsorbent capacity.

Effect of a grain challenge on ruminal, urine, and fecal pH, apparent total-tract starch digestibility, and milk composition of Holstein and Jersey cows

The effects of a grain challenge on ruminal, urine, and fecal pH, apparent total-tract starch digestibility, and milk composition were determined. Six Holstein cows, 6 rumen-cannulated Holstein cows, and 6 Jersey cows were used in a replicated 3×3 Latin square design balanced to measure carryover effects. Periods (10 d) were divided into 4 stages (S): S1, d 1 to 3, served as baseline with regular total mixed ration ad libitum; S2, d 4, served as restricted feeding, with cows offered 50% of the total mixed ration fed on S1 (dry matter basis); S3, d 5, a grain challenge was performed, in which cows were fed total mixed ration ad libitum and not fed (CON) or fed an addition of 10% (MG) or 20% (HG) pellet wheat-barley (1:1) top-dressed onto the total mixed ration, based on dry matter intake obtained in S1; S4, d 6 to 10, served as recovery stage with regular total mixed ration fed ad libitum. Overall, cows had a quadratic treatment effect for milk yield where CON (22.6kg/d) and HG (23.5kg/d) had lower milk yield than cows in MG (23.7kg/d). Jersey cows had a quadratic treatment effect for dry matter intake where cows in CON (13.2kg/d) and HG (12.4kg/d) had lower dry matter intake than cows in MG (14kg/d). Holstein cows had a linear treatment effect for dry matter intake (17.7, 18.4, and 18.6kg/d for CON, MG, and HG, respectively). Rumen pH for the rumen-cannulated cows had a linear treatment effect (6.45, 6.35, and 6.24 for CON, MG, and HG, respectively). Cows in HG spent more time with rumen pH below 5.8 (4.33 h) than MG (2 h) or CON (2.17 h) as shown by the quadratic treatment effect. Holstein cows in HG (8.46) had lower urine pH than MG (8.51) or CON (8.54) as showed by the linear treatment effect for urine pH. Apparent total-tract starch digestibility had a tendency for a linear treatment effect on S3 (97.62±1.5, 97.47±1.5, and 91.84±1.6%, for CON, MG, and HG, respectively). Fecal pH was associated with rumen pH depression as early as 15 h after feeding for Holstein cows. In conclusion, a grain challenge reduced urine pH in Holstein cows but not in Jersey cows. Holstein cows’ health were not affected when rumen pH was depressed. A potentially useful link between rumen pH and systemic (urine) pH within 2 h after feeding was quantified in Holstein cows.

Effects of high concentrations of dietary crude glycerin on dairy cow productivity and milk quality

An increasing worldwide interest in alternative fuel sources and in a more diversified energy matrix has provided incentives for the biodiesel industry, generating large amounts of the by-product crude glycerin, a potential alternative feed for dairy cows. A replicated 3×3 Latin square study was conducted to evaluate the effects of high concentrations of crude glycerin on dry matter intake, milk yield and composition, milk fatty acid profile, and blood metabolites of medium-yield cows. Ruminally cannulated Holstein cows (n=6; 587±39kg of body weight; 114±29 d in milk; and 20±1.5kg/d milk yield) were used in the study. The experimental period included 2 wk for adaptation and 1 wk for data collection. Cows were fed diets containing 0 (control), 15, or 30% crude glycerin (83% glycerol). Cows were milked, milk weights were recorded twice daily, and milk samples were collected for milk quality analyses at d 18 and 19 in each experimental period. Feeding cows with crude glycerin linearly decreased dry-matter intake, the 3.5% fat-corrected milk, and the solid-corrected milk yield. Hepatic enzymes were not affected by dietary treatments, except gamma-glutamyl transferase, which was decreased with the 15% crude glycerin diet. Serum glucose and albumin showed quadratic effect with increasing inclusion of crude glycerin. Plasma cholesterol as well as total protein linearly decreased with increasing inclusion of crude glycerin. Milk fat concentration and yield showed a quadratic effect of treatments. Solid yield decreased linearly with increasing inclusion of crude glycerin. Odd-chain fatty acids and conjugated linoleic acid in milk fat linearly increased with addition of crude glycerin in the diets. Together, these results suggest that crude glycerin has potential to replace corn; however, feeding diets in which corn is replaced with crude glycerin at 30% of dietary DM greatly reduces animal performance.

Growth and energy metabolism of Nile tilapia juveniles fed glycerol

The objective of this work was to evaluate the effect of inclusion of dietary glycerol in replacement to starch on the growth and energy metabolism of Nile tilapia juveniles. The experiment was carried out in a completely randomized design with four treatments (0, 5, 10, and 15% purified glycerol) and six replicates. Pelleted, isonitrogenous, and isocaloric diets were provided for 60 days. Growth performance parameters and muscle glucose and protein concentrations were not affected by dietary glycerol levels. The treatment with 15% glycerol presented higher levels of muscle and liver triglycerides. A quadratic effect of treatments on muscle and liver triglyceride concentrations was observed. The treatment with 0% glycerol presented higher hepatic glucose levels than the one with 15%. Treatments did not differ for concentrations of liver protein, as well as of plasma glucose, triglycerides, and protein. Treatments with 10 and 15% glycerol showed higher activity of the glucose-6-phosphate-dehydrogenase enzyme than the treatment with 5%; however, there were no significant differences in the hepatic activities of the malic and glycerol kinase enzymes. A linear positive effect of treatments was observed on the activity of the glycerol kinase enzyme in liver. Levels of glycerol inclusion above 10% in the diet of Nile tilapia juveniles characterize it as a lipogenic nutrient.

Supplementing Milk Replacer with Omega-3 Fatty Acids from Fish Oil on Immunocompetence and Health of Jersey Calves

Fifty-one Jersey bull calves (5±1 d old) were assigned to 1 of 3 milk replacers to determine the effects of increasing doses of n-3 fatty acids from fish oil on immunocompetence and health. All calves were fed a 22.5% crude protein and 18% lipid industry standard milk replacer supplemented with an additional 2% fatty acids. The 3 treatments differed only in the supplemental lipid source and included a 3:1 mix of corn and canola oils; a 1:1 blend of fish oil and the 3:1 mix of corn and canola oils; and fish oil only. All treatments were supplemented with 150mg of vitamin E/kg of milk replacer. Body weight, height at withers, and length between withers and pins were measured weekly. Fecal and respiratory scores were recorded multiple times daily, and peripheral blood samples were collected on d 0, 7, 14, 21, and 42 for hematologic and metabolic analyses. Immunocompetence of calves was evaluated in vitro by the ability of neutrophils and monocytes to phagocytose Escherichia coli and produce an oxidative burst and in vivo as the change in ear thickness after an intradermal injection of phytohemagglutinin-P, and the primary and secondary humoral responses to ovalbumin. Production and health parameters were unaffected by treatments. There were no significant treatment or treatment × time effects on phagocytosis; however, there was a significant quadratic response for the percentage of neutrophils producing an oxidative burst. Fish oil did not affect the change in ear thickness in response to phytohemagglutinin-P. There was also no treatment effect on the primary IgG humoral response to ovalbumin, but there was a significant quadratic treatment effect on the secondary IgG response. Adding fish oil to milk replacer altered various immune responses, and the effect was dose-dependent; however, neither production performance nor indices of health were altered when fish oil replaced 5 to 10% of the fatty acids in milk replacer.

Níveis de lisina digestível em rações, utilizando-se o conceito de proteína ideal, para suínos machos castrados de alto potencial genético para deposição de carne magra na carcaça dos 60 aos 95 kg

Foram utilizados 40 leitões machos castrados (peso inicial de 60,43 ± 1,56 kg e peso final de 95,66 ± 3,22 kg) de alto potencial genético para deposição de carne magra na carcaça para avaliar o efeito de níveis de lisina digestível, utilizando-se o conceito de proteína ideal, sobre o desempenho e as características de carcaça. Os animais foram distribuídos em delineamento de blocos ao acaso, com quatro tratamentos, cinco repetições e dois animais por unidade experimental. Os tratamentos consistiram de uma ração basal com 16,48% de PB, suplementada com L-lisina HCL, resultando em rações com 0,70; 0,80; 0,90 e 1,00% de lisina digestível. As rações foram suplementadas com níveis crescentes de aminoácidos sintéticos, resultando em rações com relações constantes entre os aminoácidos essenciais e a lisina, com base na digestibilidade verdadeira. Não houve efeito dos níveis de lisina digestível sobre o consumo de ração. Observou-se efeito quadrático dos tratamentos sobre o ganho de peso diário e a conversão alimentar, que aumentaram até os níveis estimados de 0,87 e 0,93% de lisina digestível, respectivamente. Os tratamentos afetaram de forma quadrática a concentração de uréia no plasma dos animais, que diminuiu até o nível de 0,83% de lisina digestível. Os níveis de lisina digestível das rações promoveram efeito linear crescente sobre o consumo diário de lisina, mas não influenciaram o comprimento de carcaça pelo método brasileiro, a área de olho-de-lombo, a espessura de toucinho no ponto P2 e os rendimentos de carne magra, gordura, pernil e lombo. O rendimento de carcaça reduziu conforme diminuíram os níveis de lisina digestível da ração. Os tratamentos influenciaram de forma quadrática a conversão alimentar em músculo, que melhorou até o nível de 0,94% de lisina digestível. O nível de 0,94% de lisina digestível verdadeira, correspondente a um consumo de 26,22 g/dia de lisina digestível (2,83 g de lisina digestível/Mcal de EM) proporcionou os melhores resultados de desempenho e características de carcaça em suínos machos castrados dos 60 aos 95 kg.

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.

Exigências de lisina digestível para juvenis de tilápia-do-nilo

Este estudo foi realizado com o objetivo de determinar a exigência de lisina digestível para juvenis de tilápia-do-nilo. Noventa e seis peixes revertidos sexualmente e com peso vivo inicial de 5,72 ± 0,10 g foram alimentados por 42 dias com quatro rações (29.51% de PB e 3.235 kcal de energia digestível/kg) contendo diferentes níveis de L-lisina HCl (0,1; 0,3; 0,5 e 0,7%, correspondendo a rações com 1,04; 1,27; 1,51 e 1,741% de lisina digestível, respectivamente). Os peixes foram distribuídos em 16 tanques com capacidade de 1.000 L cada um, em um delineamento inteiramente casualizado, com quatro tratamentos, três repetições e seis peixes por unidade experimental. Não foi observado efeito dos níveis de lisina sobre o índice hepato-somático, a gordura visceral, a sobrevivência e os teores de água e extrato etéreo na carcaça. A análise de Linear Response Plateau do ganho de peso e da conversão alimentar versus níveis de lisina digestível demonstrou estimativa de exigência de 1,56 e 1,44% de lisina digestível, respectivamente. Foi observado efeito quadrático sobre o rendimento de carcaça, que aumentou até o nível de 1,61% de lisina digestível. Considerando o desempenho, recomenda-se que dietas para juvenis de tilápia-do-nilo devem conter 1,44% de lisina digestível (5,23% da proteína da dieta).

Exigências de aminoácidos sulfurados digestíveis para suínos machos castrados, mantidos em ambiente de alta temperatura dos 15 aos 30 kg

Para determinar a exigência de aminoácidos sulfurados de suínos machos castrados, dos 15 aos 30 kg, mantidos em ambiente de alta temperatura, foram utilizados 60 leitões mestiços (Landrace x Large White), com peso inicial de 14,97 ± 0,33 kg e idade de 50,36 ± 3,29 dias. Os animais foram distribuídos em delineamento experimental de blocos ao acaso, com cinco tratamentos (0,465; 0,511; 0,558; 0,605 e 0,652% de metionina + cistina digestível), seis repetições e dois animais por unidade experimental. As rações experimentais e a água foram fornecidas à vontade até o final do experimento, quando os animais atingiram o peso de 29,87 ± 0,52 kg. A temperatura no interior da sala foi mantida em 30,9 ± 0,7ºC e a umidade relativa em 67,5 ± 7,2%. O índice de temperatura de globo e umidade calculado no período foi de 81,2 ± 1,2. Os níveis de metionina + cistina digestível da ração influenciaram o ganho de peso diário, que aumentou, e a conversão alimentar, que reduziu de forma linear. Não se observou efeito dos tratamentos sobre o consumo de ração diário. Com relação às deposições de proteína (DP) e de gordura (DG) na carcaça, verificou-se efeito quadrático dos tratamentos sobre a DG, que reduziu até o nível de 0,508%, e efeito linear crescente sobre a DP. Concluiu-se que a exigência de aminoácidos sulfurados digestíveis para suínos machos castrados, mantidos em ambiente de alta temperatura, dos 15 aos 30 kg, é de 0,558% de metionina + cistina digestível na ração, que corresponde à relação metionina + cistina digestível:lisina digestível de 60%.

Exigências de lisina, com base no conceito de proteína ideal, para suínos machos castrados, de 95 a 122kg, selecionados para deposição de carne magra

Determinaram-se as exigências de lisina para suínos machos castrados utilizando-se 40 animais distribuídos em delineamento experimental de blocos ao acaso, com cinco tratamentos (0,5; 0,6; 0,7; 0,8 e 0,9% de lisina total), quatro repetições e dois animais por baia. Adicionaram-se aminoácidos sintéticos para se manter o nível de acordo com o perfil da proteína ideal. Observou-se efeito quadrático dos tratamentos sobre o ganho de peso diário, espessura do toucinho na 10ª costela, espessura do toucinho na última costela e conversão alimentar. Houve efeito linear sobre o consumo de lisina diário e taxa de deposição de carne magra diária. O modelo linear response plateau ajustou-se melhor aos resultados da taxa de deposição de carne magra diária. Não houve efeito sobre o consumo de ração diário, espessura de toucinho no P1, espessura de toucinho no P2, profundidade de lombo, porcentagem de carne magra, rendimento de carcaça, comprimento de carcaça pelo método brasileiro, comprimento de carcaça pelo método americano e rendimento de pernil. A exigência de lisina total para suínos machos castrados de 95 a 122kg, selecionados para deposição de carne magra na carcaça, é de 0,76%, correspondendo ao consumo de 25,99g/dia.

Lisina em rações para suínos machos castrados selecionados para deposição de carne magra na carcaça dos 95 aos 110 kg

Foram utilizados 60 suínos machos castrados, provenientes de cruzamento entre híbridos comerciais, com peso inicial médio de 95,7 ± 0,8 kg e final de 109,8 ± 1,1 kg para avaliar diferentes níveis de lisina sobre o desempenho e as características de carcaça. Foi usado o delineamento de blocos ao acaso, com cinco tratamentos, seis repetições e dois animais por repetição. Os tratamentos corresponderam a uma ração basal com 13,7% de proteína bruta, 3367 kcal de ED/kg e suplementada com cinco níveis de L-lisina-HCl, resultando em rações com 0,50; 0,60; 0,70; 0,80 e 0,90% de lisina total. O consumo de ração diário reduziu de forma linear. Entretanto, ficou caracterizada maior ingestão de lisina com o aumento da concentração dietética do aminoácido. Verificou-se efeito quadrático do nível de lisina sobre a conversão alimentar, que melhorou até o nível de 0,76% de lisina, e sobre a conversão alimentar em músculo, que reduziu de forma linear. No entanto, os dados ajustados pelo modelo "Linear Response Plateau" indicaram o nível de 0,79% para a melhor conversão alimentar em músculo. O ganho de peso, comprimento de carcaça, espessura de toucinho, rendimento de pernil, rendimento de carne magra e a área de olho de lombo não foram influenciados pelos tratamentos. Para o genótipo estudado, o nível de 0,76% de lisina total na ração foi o indicado para machos castrados, dos 95 aos 110 kg, correspondendo à ingestão diária estimada de 23,8 g de lisina.

Conjugated linoleic acid changes swine performance and carcass composition.

Conjugated linoleic acid (CLA) is a collective term for positional and geometric isomers of linoleic acid. Dietary CLA has been shown to improve feed efficiency, decrease body fat, and increase lean tissue in laboratory animals. We hypothesized that CLA would improve performance and carcass composition and would be deposited in pork tissues. Diets of 40 crossbred pigs were supplemented with CLA to determine its effects on performance and carcass composition. Eight replications of five littermate barrows with an initial average weight of 26.3 kg were allotted at random to individual pens. Within replication dietary treatments containing 0, 0.12, 0.25, 0.5, or 1.0% CLA were assigned at random. Pigs were weighed and feed disappearance was determined at 14-d intervals. Average daily gain increased linearly as the level of CLA increased in the diet (P < 0.05). Average daily feed intake was not affected by the concentration of CLA in the diet. Therefore, a linear increase in gain:feed ratio (P < 0.05) was observed. Carcasses from animals fed control diets had greater 10th rib backfat than carcasses from animals fed CLA (P < 0.05). Ultrasound measurement and carcass measurements showed less fat depth over the loin eye at the 10th rib of pigs fed doses of CLA (P < 0.05) than that observed for control pigs. Belly hardness (firmness) increased linearly as the concentration of CLA in the diet increased when bellies were measured for firmness either lean side up (P < 0.001) or lean side down (P < 0.05). Loin dissection data demonstrated that CLA produced a quadratic treatment effect both for less intermuscular fat (P < 0.001) and less subcutaneous fat (P < 0.05) and a linear increase for bone (P < 0.05), although finished loin weight only tended to increase (P = 0.08). The CLA concentration increased in a linear relationship in both subcutaneous fat (P < 0.001) and lean tissue (P < 0.001). Dietary CLA was incorporated into pig tissues and had positive effects on performance and body composition.