Protein Physiology and Its Application in the Lactating Cow: The Metabolizable Protein Feeding Standard

Abstract

The metabolizable protein (MP) feeding standard for lactating cows represents a balance between animal requirements for metabolizable amino acids (MAAs) and their fulfillment by diets composed of a wide variety of feedstuffs. One additional measurement for feedstuffs, the .urea-fermentation-potential (UFP), is utilized when urea is a part of the diet. Although the MP standard is an amiho kei'd (AA) standard, nevertheless, an alte/'fiativd ~if~gle-value MP standard was approximated ~H~out resorting to calculations for each ess~iatlal 'AA. The net protein (NP) of body origin ifi the feces was estimated to be 12 g/kg 0~ dry matter (DM) consumed. This amount Was regarded as a feedstuff expense of digestion reducing the quantity of MP available for productive purposes such as lactation. The estimation of rumen microbial protein synthesis as 10.4% of total digestible nutrients (TDN) is based upon three evaluations. The first is that 52% of ration TDN undergoes digestion within the rumen. The second is that 25% of the digested TDN is transformed into microbial crude protein when adequate nitrogen is present. The third evaluation is that 80% of the microbial protein is alpha-amino. The 80% true digestibility value for abomasal microbial protein synthesized within the rumen is based upon cattle and sheep metabolism trials. Semi-purified diets 1

Performance of growing steers fed quackgrass hay supplemented with canola meal

“…These results cannot be attributed only to intestinal availability of dietary amino acids, since soybean meal supplies less dietary amino acids than fish meal (Santos et al 1984) (Veira et al 1990(Veira et al , 1991. However, when hay is used, protein supplementation may improve gain as well as intake, with the effect being more evident when low-quality hay is fed (Egan 1965;McCollum and Galyean 1985;Yang et al 1986 Burroughs et al (1975).…”

Growth, cellular development of skeletal muscle and body composition of rats selected for post weaning gain

“…The study of the cellular development of skeletal muscle during the 4-9 week growth period shows that the gastrocnemius muscles of high line rats were larger at 9 weeks of age (2.17 g) than low line (1.55 g) rats at the same age (Table 9)« Consequently, the muscle of high line rats was growing at a faster rate (262 mg/day, high line Protein requirement (mg) = 133-1 (W) ' ^ x 6.25 (maintenance, Armstrong and Mitchell, 1955) plus protein deposition/.53 (Burroughs et al, 1975)/-93 (digestibility of protein). ^Apparent energy digestibility (intake-fecal/intake).…”

Effects of cottonseed meal supplementation on the performance and pasture utilization by Zebu steers

“…Undegraded feed MP and microbial MP were expressed according to Burroughs et al (1974). The escaped values of CP of tropical forage have not been well documented; however, according to Burroughs et al (1975aBurroughs et al ( , 1975b, low protein roughage (containing less than 7% CP)…”

“…However, factors such as supplementary feeds to grazing animals during the dry season need further consideration. The objective of this study was to put together data from available sources and those obtained from grazing trials (Njoya and Trenkle, 1992) into a model, using the metabolizable protein system (Burroughs et al, 1974(Burroughs et al, , 1975a(Burroughs et al, , 1975b) and the net energy system (NRC, 1984), to estimate the energy and protein requirements for maintenance and predict response to feed supplements of grazing cattle in Sub-Saharan environments. The final objective was to predict when supplementing energy, protein, or both to grazing Zebu cattle may be economically beneficial.…”

“…The metabolizable protein system (MP) based on the amino acids (AA) required by body tissues and the supply of absorbed AA from undegraded feed protein and rumen microbial protein digested in the intestine (Burroughs et al, 1974(Burroughs et al, , 1975a(Burroughs et al, , 1975b …”