Urea, meat meal or lupins as nitrogen supplements to barley and hay diets for yearling cattle at two levels of body condition

Abstract

Weaner steers were fed to attain either fat score 1 or 2 by the time that they were 1 year of age. Animals at each fat score were then either slaughtered or fed ad libitum on a basal barley and hay diet containing 11% crude protein or similar diets supplemented by either urea, meat meal or sweet lupins to contain 13% crude protein in the dry matter. Those fed were slaughtered as they attained fat score 3. Compared with those starting at fat score 2, the yearlings at fat score 1 had the same daily feed intake and thus a 10% higher relative intake, grew 15% faster and required 11% less feed per kg liveweight gain. However, they required only 6% less feed per kg carcass weight gain, owing to their 1% lower dressing percentage. The diets supplemented with the three different sources of supplementary nitrogen gave similar improvements over the basal diet in intake, growth rate and efficiency, and there were no interactions between diet and fat score. It was concluded that both the National Research Council and Agricultural Research Council feeding standards underestimate the nitrogen concentration required in grain and hay diets to ensure maximum performance and efficiency by yearling cattle growing from 220 to 370 kg liveweight, and that supplements of either urea, meat meal or lupins providing an extra 2 percentage units of crude protein improve performance to a similar extent.

Understanding the nutritional chemistry of lupin (Lupinus spp.) seed to improve livestock production efficiency

“…In many studies with ruminants, the positive responses recorded when lupins are fed are a result of an increased nutrient supply to the animal rather than speci®c bene®cial components within the lupins. Often the control within the experiment consists of moderate quality pasture with no grain or grain ± legume supplementation (Carbon et al 1972;Searle & Graham, 1980;Hawthorne, 1982Hawthorne, , 1984Hodge et al 1982;Hawthorn & Stacey, 1984;Barker et al 1985;Butler & McDonald, 1986;Morcombe et al 1987;Rojas & Carrasco, 1987;Cottle, 1988;Curtis & Mavrantonis, 1990;Hinch & Thwaites, 1990;Morcombe & Ferguson, 1990;Robertson & Hinch, 1990;Thompson & Curtis, 1990;Godfrey et al 1993;May et al 1993). Similarly, comparisons between lupins and other grain legumes as a nutrient source for ruminants often re¯ects differences in the total content of nutrients, rather than superior digestibility or feeding qualities (e.g.…”

Evaluación Productiva Y Económica De Urea, Grano De Lupino, Expeller De Maní Y Afrecho De Soya en Raciones De Engorda De Vaquillas

“…También los consumos de alimentos y de energía metabolizable obtenidos son similares a los señalados por la AFRC (1995) para vaquillas de 400 kg de peso y 1,25 kg de incremento de peso diario. Sin embargo, el consumo de proteína cruda fue aproximadamente 20% mas alto en este estudio, respecto de la misma fuente, lo cual estuvo de acuerdo a lo programado y respondió a que experiencias anteriores señalaron limitaciones en el consumo voluntario e incrementos de pesos al emplear raciones con valores tabulares en este nutriente (Barker et al, 1985;Rojas et al, 2003;Rojas y Manríquez, 2007). De acuerdo Galyean (1996) la mayoría de los trabajos de engorda intensiva con buenas respuestas productivas los niveles de proteína cruda se encuentran en el rango entre 12,5 y 14,4%.…”

“…La similitud en los incrementos de peso y consumo entre los tratamientos está indicando que todas las fuentes de proteína usadas, bajo las condiciones de este estudio, son similares desde el punto de vista de la respuesta animal. Estos resultados coinciden con los obtenidos por Barker et al,(1985) quienes no observaron diferencias en incrementos de peso y consumo al alimentar novillos con raciones isoproteicas de harina de carne, lupino australiano o urea. Resultados similares en consumo e incremento de peso se obtuvieron en corderos y novillos al usar raciones diferenciadas que contenían Cuadro 3.…”