Influence of arrival weight of Holstein steers of similar age on feedlot growth performance, dietary energetics, and carcass characteristics.

Objective: Evaluate the effect of arrival weight on feedlot growth performance and carcass characteristics of Holstein steers of similar age. Material and Methods: Three hundred calf-fed Holstein steers (age 113 ± 1-day) were distributed in a completely randomly unbalanced design and divided into five categories (105, 112, 117, 123, and 129 kg) of shrunk initial weight (SIW). Calves were weighed on days 1, 112, 224, and 361. Calves were fed steam-flaked corn-based diets. Growth performance and dietary energy were evaluated for each period and the study as a whole (1-361-day). Results: During the rearing period, average daily gain (ADG) increased (linearly effect, p < 0.01) with increasing birth weight. Birthweight was positively associated (p < 0.05) with feedlot arrival weight (R 2 = 0.47) and final harvest weight (R 2 = 0.36). Overall ADG increased (p < 0.01) with increasing SIW. Dry matter intake increased linearly during the first 224-day but quadratically during the last 137 days. Overall, there was a quadratic effect (p < 0.05) of SIW on gain-to-feed and observed-to-expected dietary NE, with lower efficiencies (4%) for steers in both the lightest and heaviest SIW. Hot carcass weight, Longissimus muscle area, marbling score, and fat thickness increased (linear effect, p ≤ 0.03) as SIW increased, whereas kidney-pelvic-heart fat and yield-grade were unaffected. Conclusions: The initial arrival weight influences the growth performance, energetic efficiency, and carcass characteristics of Holstein steers of similar age. The effect is more pronounced in the lighter (<112 kg) steers.

Feedlot growth, carcass characteristics and meat quality of hair breed male lambs exposed to seasonal heat stress (winter vs. summer) in an arid climate.

Twenty Dorper × Katahdin male lambs (body weight = 33.9 ±â€¯0.4 kg and age = 4.5 months) were individually housed for a 30-d feeding period to evaluate the effects of seasonal heat stress (winter [n = 10] vs. summer [n = 10]) on feedlot performance, carcass traits, wholesale cut yields and meat quality. Heat stress environmental conditions prevailed in summer and mostly thermoneutral in winter. Overall growth rate and feed efficiency, as well as empty body weight at slaughter, cold carcass weight, omental fat percentage, and loin yield were lower in summer than in winter. Kidney-pelvic-heart fat deposition and yields of hot carcass, neck and shoulder increased during summer. Postmortem aging of meat during 14 d exhibited higher lightness, redness, yellowness and toughness in summer. In conclusion, summer heat stress decreased growth and feed efficiency without affecting feed intake of hair male lambs. Additionally, heat stress improved carcass yield with no detrimental changes on meat quality.

Growth, carcass characteristics, cut yields and meat quality of lambs finished with zilpaterol hydrochloride and steroid implant.

Forty hairbreed male lambs were used to evaluate the effects of zilpaterol hydrochloride (ZH, 0 and 0.15 mg/kg BW) and steroid implant (SI, without and with 52.5 mg trenbolone acetate and 7.5 mg 17ß-estradiol) on feedlot performance, carcass characteristics, non-carcass components, wholesale cut yield, and meat quality. Supplemental ZH increased growth rate, feed efficiency, carcass weight, and dressing percentage, with no effect on wholesale cut yields. Feeding ZH increased muscle pH at 24 h. Supplemental ZH increased meat shear force, but decreased lightness, redness, and yellowness after frozen storage followed by a 14-day aging period. The SI administration increased dressing percentage and neck yield, but decreased testicle weight and meat redness, without affecting other variables. The LT area was greater with ZH + SI administration than with individual application of ZH or SI. Compared to individual administration, simultaneous application of ZH and SI did not result in improved growth performance, carcass traits and wholesale cut yields in hairbreed male lambs.

Effect of energy density and virginiamycin supplementation in diets on growth performance and digestive function of finishing steers.

OBJECTIVE: This study was determined the influence of virginiamycin supplementation on growth-performance and characteristics of digestion of cattle with decreasing dietary net energy value of the diet for maintenance (NEm) from 2.22 to 2.10 Mcal/kg. METHODS: Eighty crossbred beef steers (298.2±6.3 kg) were used in a 152-d performance evaluation consisting of a 28-d adaptation period followed by a 124-d growing-finishing period. During the 124-d period steers were fed either a lesser energy dense (LED, 2.10 Mcal/kg NEm) or higher energy dense (HED, 2.22 Mcal/kg NEm) diet. Diets were fed with or without 28 mg/kg (dry matter [DM] basis) virginiamycin in a 2×2 factorial arrangement. Four Holstein steers (170.4±5.6 kg) with cannulas in the rumen (3.8 cm internal diameter) and proximal duodenum were used in 4×4 Latin square experiment to study treatment effects on characteristics of digestion. RESULTS: Neither diet energy density nor virginiamycin affected average daily gain (p>0.10). As expected, dry matter intake and gain efficiency were greater (p<0.01) for LED- than for HED-fed steers. Virginiamycin did not affect estimated net energy value of the LED diet. Virginiamycin increased estimated NE of the HED diet. During daylight hours when the temperature humidity index averaged 81.3±2.7, virginiamycin decreased (p<0.05) ruminal temperature. Virginiamycin did not influence (p>0.10) ruminal or total tract digestion. Ruminal (p = 0.02) and total tract digestion (p<0.01) of organic matter, and digestible energy (p<0.01) were greater for HED vs LED. Ruminal microbial efficiency was lower (p<0.01) for HED vs LED diets. CONCLUSION: The positive effect of virginiamycin on growth performance of cattle is due to increased efficiency of energy utilization, as effects of virginiamycin on characteristics of digestion were not appreciable. Under conditions of high ambient temperature virginiamycin may reduce body temperature.

Influence of methionine supplementation of growing diets enriched with lysine on feedlot performance and characteristics of digestion in Holstein steer calves.

OBJECTIVE: Two trials were conducted in order to examine the effects of level of supplemental methionine on productive performance, dietary energetic, plasma amino acid concentration, and digestive function. METHODS: Dietary treatments consisted of a steam-flaked corn-based diet containing urea as the only source of supplemental nitrogen supplemented with no supplemental amino acid (control), or control plus 1.01% lysine and 0.032%, 0.064%, 0.096%, or 0.128% methionine. In Trial 1, 150 Holstein steer calves (127±4.9 kg) were utilized to evaluate the influence of treatments on growth-performance, dietary energetic, plasma amino acid concentration during the first 112 days of growing period. During the initial 56-d period calves received the 5 experimental diets. During the subsequent 56-d period all calves were fed the control diet. RESULTS: During the initial 56-d period, methionine supplementation increased (linear effect, p<0.01) plasma methionine. In the presence of supplemental lysine, increases on level of methionine in diet did not affect average daily gain. However, increased gain efficiency (quadratic effect, p = 0.03) and estimated dietary net energy (NE; linear effect, p = 0.05). Estimated metabolizable methionine supply was closely associated (R2 = 0.95) with efficiency NE utilization for maintenance and gain. During the subsequent 56-d period, when all calves received the control diet (no amino acid supplementation), plasma amino acid concentrations and growth performance was not different among groups. However, the effects of methionine supplementation during the initial 56-period carried over, so that following a 56-d withdrawal of supplementation, the overall 112-d effects on gain efficiency (quadratic effect, p = 0.05) dietary NE (linear effect, p≤0.05) remained appreciable. In Trial 2, 5 cannulated Holstein steers were used to evaluate treatment effects on characteristics of digestion and amino acid supply to the small intestine. There were no treatment effects on flow of dietary and microbial N to the small intestine. Postruminal N digestion increased (p = 0.04) with increasing level of supplemental methionine. Methionine supplementation linearly increased (p<0.01) duodenal flow of methionine. Likewise, lysine supplementation increased an average of 4.6% (p = 0.04) duodenal flow of lysine. In steers that received non-supplemented diet, observed intestinal amino acid supply were in good agreement with expected. CONCLUSION: We conclude that addition of rumen-protected methionine and lysine to diets may enhance gain efficiency and dietary energetics of growing Holstein calves. Observed amino acid supply to the small intestine were in good agreement with expected, supportive of NRC (2000, Level 1).

Influence of Kaolinite Clay Supplementation on Growth Performance and Digestive Function in Finishing Calf-fed Holstein Steers.

Two experiments were conducted to examine the influence of kaolinite clay supplementation (0%, 1%, or 2% diet dry matter [DM] basis) on characteristics of digestion (Trial 1) and growth performance (Trial 2) in calf-fed Holstein steers fed a finishing diet. In Trial 1, 6 Holstein steers (539±15 kg) with ruminal and duodenal cannulas were used to evaluate treatment effects on characteristics of digestion. Kaolinite clay supplementation decreased total tract DM digestion (linear effect, p<0.01) without effects (p≥0.10) on site and extent of digestion of organic matter, neutral detergent fiber, starch and N, or ruminal microbial efficiency. There were no treatment effects on ruminal pH, volatile fatty acids molar proportions or estimated methane production. In Trial 2, 108 Holstein steers (132.4±5.6 kg) were used in a 308-d study to evaluate growth performance and carcass characteristics. There were no treatment effects (p>0.10) on average daily gain (ADG) and gain efficiency (ADG/dry matter intake). Kaolinite supplementation tended (linear effect, p = 0.08) to increase dietary net energy (NE) during the initial 112-d period. However, the overall (308-d) effect of supplementation dietary NE was not appreciable (p>0.20). However, due to the inertness of kaolinite, itself, the ratio of observed-to-expected dietary NE increased with kaolinite supplementation. This effect was more pronounced (linear effect, p 0.03) during the initial 224 d of the study. Overall (308 d), kaolinite supplementation tended to increase (linear effect, p = 0.07) dietary NE by 3% over expected. Kaolinite supplementation did not affect carcass weight, yield grade, longissimus area, kidney, pelvic and heart fat, and quality grade, but decreased (linear effect, p = 0.01) dressing percentage. It is concluded that kaolinite supplementation up to 2% of diet DM may enhance energetic efficiency of calf-fed Holstein steers in a manner independent of changes in characteristics of ruminal and total tract digestion.

Influence of ruminal degradable intake protein restriction on characteristics of digestion and growth performance of feedlot cattle during the late finishing phase.

Two trials were conducted to evaluate the influence of supplemental urea withdrawal on characteristics of digestion (Trial 1) and growth performance (Trial 2) of feedlot cattle during the last 40 days on feed. Treatments consisted of a steam-flaked corn-based finishing diet supplemented with urea to provide urea fermentation potential (UFP) of 0, 0.6, and 1.2%. In Trial 1, six Holstein steers (160 ± 10 kg) with cannulas in the rumen and proximal duodenum were used in a replicated 3 × 3 Latin square experiment. Decreasing supplemental urea decreased (linear effect, P ≤ 0.05) ruminal OM digestion. This effect was mediated by decreases (linear effect, P ≤ 0.05) in ruminal digestibility of NDF and N. Passage of non-ammonia and microbial N (MN) to the small intestine decreased (linear effect, P = 0.04) with decreasing dietary urea level. Total tract digestion of OM (linear effect, P = 0.06), NDF (linear effect, P = 0.07), N (linear effect, P = 0.04) and dietary DE (linear effect, P = 0.05) decreased with decreasing urea level. Treatment effects on total tract starch digestion, although numerically small, likewise tended (linear effect, P = 0.11) to decrease with decreasing urea level. Decreased fiber digestion accounted for 51% of the variation in OM digestion. Ruminal pH was not affected by treatments averaging 5.82. Decreasing urea level decreased (linear effect, P ≤ 0.05) ruminal N-NH and blood urea nitrogen. In Trial 2, 90 crossbred steers (468 kg ± 8), were used in a 40 d feeding trial (5 steers/pen, 6 pens/ treatment) to evaluate treatment effects on final-phase growth performance. Decreasing urea level did not affect DMI, but decreased (linear effect, P ≤ 0.03) ADG, gain efficiency, and dietary NE. It is concluded that in addition to effects on metabolizable amino acid flow to the small intestine, depriving cattle of otherwise ruminally degradable N (RDP) during the late finishing phase may negatively impact site and extent of digestion of OM, depressing ADG, gain efficiency, and dietary NE.

Ileal amino acid digestibility and performance of pigs fed grain sorghum-based diets supplemented with phytase

Se realizaron dos experimentos para determinar el efecto de la adición de fitasa a dietas sorgo-pasta de soya en la digestibilidad ileal aparente (DIA) de aminoácidos (AA) y el comportamiento de cerdos en crecimiento. En un experimento, seis cerdos (peso promedio inicial 86,1kg) adaptados con una cánula simple tipo T en íleon terminal, fueron alimentados con tres dietas de acuerdo con un cuadro Latino repetido 3x3. La Dieta 1 fue la dieta base sorgo-pasta de soya; las Dietas 2 y 3 fueron la Dieta 1 adicionada con 500 y 1000 unidades de actividad de fitasa (FTU)/kg alimento, respectivamente. No se encontró efecto de la adición de fitasa en la DIA de AA (P>0,10). La DIA de arginina fue la más elevada y la de treonina la más baja. En otro experimento se distribuyeron aleatoriamente 28 cerdos (peso promedio inicial 22,9kg) en cuatro dietas (siete repeticiones/tratamiento) de acuerdo con un diseño de bloques completos al azar. Las dietas fueron: 1) dieta base sorgo-pasta de soya y 0,67% lisina digestible en íleon; 2) dieta base +350FTU/kg de alimento; 3) dieta base +700FTU; 4) dieta base +1050FTU. La dieta base cubría 100% el requerimiento de P disponible para cerdos de 20-50kg. Los análisis de regresión no mostraron efecto de la adición de fitasa en la ganancia diaria de peso (P=0,93); consumo de alimento, lisina y treonina (P=0,37); ni en la conversión alimenticia (P=0,54). Los cerdos alimentados con dieta base tendieron a tener una mayor ganancia de peso que los que recibieron la dieta 2 (P=0,09) o la dieta 3 (P=0,11). Los resultados indican que la fitasa no afecta el suministro de AA digestibles o, como consecuencia, el comportamiento de cerdos alimentados con dietas sorgo-pasta de soya.

Two experiments were conducted to determine the effect of phytase supplementation to sorghum-soybean meal diets on the apparent ileal digestibility (AID) of amino acids (AA) and performance of growing pigs. In one experiment, six pigs (average initial BW 86.1kg) fitted with a simple T-cannula at the distal ileum, were fed three diets in a repeated 3x3 Latin square design. Diet 1 was the basal sorghum-soybean meal diet. Diets 2 and 3 were the basal diet supplemented with phytase at 500 and 1000 units of phytase activity (FTU/kg diet), respectively. There was no effect of phytase supplementation on the AID of AA (P>0.10). Arginine AID was highest and threonine AID was lowest. In the second experiment, 28 pigs (average initial BW 22.9kg) were allotted to four diets (seven replicates/treatment) in a randomized complete block design. Diets were: 1) sorghum-soybean meal, basal diet, 0.67% apparent ileal digestible lysine; 2) basal diet +350FTU/kg diet; 3) basal +700FTU; 4) basal +1050FTU. The basal diet contained 100% of the available P requirement for pigs 20-50kg. Linear regression analyses showed no effect of phytase supplementation on average daily gain (ADG; P=0.93), feed (P=0.37), lysine (P=0.37) and threonine (P=0.37) intakes, or feed conversion (P=0.54). Pigs fed the basal diet tended to have higher ADG than those fed diet 2 (P=0.09) or diet 3 (P=0.11). Results indicate that phytase supplementation does not affect the supply of digestible AA or, as a consequence, the performance of pigs fed sorghum-soybean meal diets.

Realizaram-se dois experimentos para determinar o efeito da adição de fitasa a dietas sorgo-pasta de soja na digestibilidade ileal aparente (DIA) de aminoácidos (AA) e o comportamento de cerdos em crescimento. Em um experimento, seis cerdos (peso médio inicial 86,1kg) adaptados com uma cânula simples tipo T em íleon terminal, foram alimentados com três dietas de acordo com um quadro Latino repetido 3x3. A Dieta 1 foi a dieta base sorgo-pasta de soja; as Dietas 2 e 3 foram a Dieta 1 adicionada com 500 e 1000 unidades de atividade de fitasa (FTU)/kg alimento, respectivamente. Não encontrou-se efeito da adição de fitasa na DIA de AA (P>0,10). A DIA de arginina foi a mais elevada e a de treonina a mais baixa. Em outro experimento se distribuiram aleatoriamente 28 cerdos (peso médio inicial 22,9kg) em quatro dietas (sete repetições/tratamento) de acordo com um desenho de blocos completos ao azar. As dietas foram: 1) dieta base sorgo-pasta de soja e 0,67% lisina digestiva em íleon; 2) dieta base +350FTU/kg de alimento; 3) dieta base +700FTU; 4) dieta base +1050FTU. A dieta base cobria 100% o requerimento de P disponível para cerdos de 20-50kg. As análises de regressão não mostraram efeito da adição de fitasa na ganância diária de peso (P=0,93); consumo de alimento, lisina e treonina (P=0,37); nem na conversão alimentícia (P=0,54). Os cerdos alimentados com dieta base tenderam a ter uma maior ganância de peso que os que receberam a dieta 2 (P=0,09) ou a dieta 3 (P=0,11). Os resultados indicam que a fitasa não afeta o subministro de AA digestivos ou, como conseqüência, o comportamento de cerdos alimentados com dietas sorgo-pasta de soja.

Limiting amino acids in wheat for growing-finishing pigs

Se realizaron cuatro experimentos con 136 cerdos cruzados (Landrace-Hampshire-Duroc) para determinar el orden de los tres primeros aminóacidos limitantes (AAL) en trigo para cerdos en crecimiento y finalización. Los tratamientos consistieron en adiciones de lisina, treonina y/o metionina a dietas base y una dieta testigo. En el Exp. 1. lisina incrementó la ganancia diaria de peso (GDP), consumo de alimento (CDA), lisina (CDL), treonina (CDT) y metionina (CDM), y mejoró la conversión alimenticia (C/G). La adición de treonina incrementó GDP y CDT, y mejoró C/G. Metionina incrementó el CDM, pero no afectó GDP o C/G. En el Exp. 2, treonina incrementó GDP y CDT, e incrementó C/G. La inclusión de metionina tendió a reducir GDP y a deprimir C/G. No hubo diferencias en GDP, CDA o C/G entre los cerdos bajo dieta base con lisina y treonina o dieta testigo; aunque los testigos tuvieron mayor CDT y CDM. En el Exp. 3, treonina sola no afectó GDP o C/G, pero combinada con metionina incrementó GDP y mejoró C/G. No hubo diferencias en GDP y C/G entre las dietas testigos y la adicionada con lisina y tronina. En el Exp. 4, treonina tendió a incrementar GDP y a mejorar C/G, mientras que metionina redujo GDP. La adición de treonina y metionina incrementó GDP, pero no afectó CDA ni C/G. Estos datos indican que, en trigo, lisina, y treonina son el primero y segundo AAL para cerdos en crecimiento y finalización. Metionina sola no limita el crecimiento de cerdos en dietas con base trigo, pero parece potenciar la respuesta de treonina en cerdos de finalización. Lisina y treonina pueden sustituir la pasta de soya en dietas con base trigo para cerdos en crecimiento y finalización.

Predicción del contenido de aminoácidos en el trigo con base en su valor de proteína / Prediction of the moderate of aminoacids in the wheat with base in itsvalue of protein

Se analizó la composición de aminoácidos en trigos producidos comercialmente, y se generaron modelos para predecir el contenido de aminoácidos con base en el contenido de proteína cruda en este cereal. Se colectaron 150 muestras del cereal de la cosecha del 2001, las cuales se agruparon en tres lotes (alto, medio y bajo) de acuerdo con su porcentaje de proteína cruda. De cada grupo se tomaron 9 muestras en que analizó el contenido de aminoácidos. Se realizaron analísis de correlación y regresión entre los contenidos de aminoácidos y de proteínas real (suma de todos los aminoácidos). Se observó una variedad alta (CV de 7,4 a 14 por ciento en el contenido de proteína cruda y de aminoácidos en los trigos evaluados. Los aminoácidos no esenciales fueron los principales responsables de esta variedad debido a su mayor contenido, en comparación con los esenciales. Lisina, treonina y metionina son de variabilidad intermedia. Glutamato y prolina son los aminoácidos más abundantes en el trigo. Las ecuaciones de regresión de los dos primeros aminoácidos limitativos en trigo fueron las siguientes: Lisina = 0,15982 ñ 0,012 + 0,01709 ñ 0,001 (p<0,01; R² = 0,897); Treonina = 0,08364 ñ 0,011 + 0,02293 ñ 0,001 (P<0,01; R² = 0,952). Con base en los análisis de regresión, se concluye que el contenido de proteína es un buen estimador del contenido de aminoácidos en los trigos y que los modelos de regresión obtenidos en este estudio permiten ahorrar tiempo y costo en la determinación del contenido de aminoácidos