Effect of beef type, body weight and dietary protein content on voluntary feed intake, digestibility, blood and urine metabolites and nitrogen retention

Abstract

Summary Six normal‐conformation and six double‐muscled Belgian White‐blue bulls were involved in a 2 × 2 × 2 factorial experiment to investigate the effect of genotype (normal versus double‐muscled), body weight (400 versus 600 kg) and dietary crude protein (135 versus 165 g per kg dry matter) on voluntary feed intake, digestion and its consequences on the nutritive value, metabolites in blood and urine and nitrogen retention. The diet consisted of concentrate and maize silage (50:50, dry matter basis) and was fed ad libitum. Double‐muscled bulls showed a significantly lower feed consumption (67.1 g DM per kg W0.75) compared to normal bulls (81.5 g). When adjusted for dry matter intake, digestibility was not affected by beef type. Some feed components tended to be better digested when body weight (crude fibre and nitrogen‐free extractives) or dietary crude protein content (dry matter, organic matter, crude protein, nitrogen‐free extractives and energy) were higher. Blood urea nitrogen was not dependent on genotype, but increased with body weight and dietary protein. Creatinine concentration in the blood and daily creatinine excretion in the urine were highest in double‐muscled bulls and heavier animals. Urinary 3‐methylhistidine excretion was not different between double‐muscled and normal bulls, but increased with body weight. This was confirmed by the fact that nitrogen retention relative to intake was similar for both beef types and decreased with a higher body weight. A negative effect of stress on feed intake, muscle protein degradation and nitrogen retention in double‐muscled bulls was not excluded. Zusammenfassung Einfluß von Genotyp, Lebendmasse und Proteingehalt der Ration auf Futteraufnahme, Verdaulichkeit, Metaboliten im Blut und Harn und Stickstoffbilanz. Der Einfluß von Genotyp (konventionell oder Doppellender), Lebendmasse (400 und 600 kg) und Proteingehalt der Ration (135 oder 165 g Rohprotein pro kg Trockensubstanz) auf Verdaulichkeit, Metaboliten im Blut und Harn und Stickstoffbilanz wurde mit 6 konventionellen Bullen und 6 Doppellendern der Belgischen weißblauen Rasse untersucht. Die Ration bestand aus Kraftfutter und Maissilage (50:50 auf Basis von Trockensubstanz) und wurde ad libitum gefüttert. Die Trockensubstanzaufnahme der Doppellender lag niedriger im Vergleich mit den konventionellen Bullen (67, 1 bzw. 81, 5 g pro kg LM0.75). Nach mathematischer Anpassung an die verschiedene Trockensubstanzaufnahme war die Verdaulichkeit nicht durch den Genotyp beeinflußt. Die Verdaulichkeit einiger Futterkomponenten lag höher, wenn die Lebendmasse (Rohfaser, N‐freie Extraktstoffe) und der Proteingehalt (Trockensubstanz; Organische Substanz, Protein, N‐freie Extraktstoffe und Energie) höher waren. Die Blutharnstoffkonzentration war nicht abhängig vom Genotyp, aber sie erhöhte sich mit der Lebendmasse und dem Proteingehalt. Die Blutkreatininkonzentration und die tägliche Exkretion im Harn lagen höher bei den Doppellendern und den schweren Tieren. Die 3‐Methylhistidinexkretion im Harn war nicht verschieden...

Effect of rumen-degradable protein balance deficit on voluntary intake, microbial protein synthesis, and nitrogen metabolism in growing double-muscled Belgian Blue bulls fed corn silage-based diet1,2,3

“…Total tract and ruminal digestibility of OM, NDF, and starch were not negatively influenced by OEB deficit (Table 4). Total tract and ruminal digestibility measured in this experiment were consistent with those generally measured on double-muscled Belgian Blue bulls (Fiems et al, 1997;Valkeners et al, 2006). According to these results, the fiber and starch degradation activities of the rumen microbes were not affected by a lack of ruminally available N, meaning that the energy availability for animal maintenance and growth were the same for the 3 diets.…”

Effect of cull potatoes in the diet for finishing Belgian Blue double-muscled cows

“…The chemical composition and the nutritive value corresponds well with data of De Boever et al (1983) and Lisiń ka and Leszczyń ski (1989). Because of their constant high-energy value, they are interesting feeds for double-muscled animals with a reduced intake capacity (Fiems et al, 1997). Boucqué et al (1982) did not find an increased daily gain in dual-purpose Belgian Blue bulls when the finishing diet contained 40% culled potatoes as a substitute for maize silage.…”

“…Potatoes have a high-energy value, mainly as a consequence of a high and constant digestibility of the organic matter (De Boever et al, 1983). Double-muscled animals are characterized by a lower feed intake capacity than non-double-muscled animals (Fiems et al, 1997) and potatoes resulted in an increased intake in Belgian Blue double-muscled (BBDM) finishing bulls (unpublished data). Intramuscular fat content in double-muscled animals is rather low (Fiems et al, 2003), even lower than 1% in some cases.…”

Effect of supplementation on the performance of grazing Belgian Blue double-muscled heifers

“…However, previous work with growing BBDM animals showed that performances were low, even when an energy supplement was fed (Fiems et al, 2002b). This is mainly a consequence of the reduced feed intake capacity of double-muscled animals (Fiems et al, 1997). The high moisture content of grass may contribute to the bulk of the diet because of the intracellular water (Forbes, 1995).…”