ALBERT

Beschreibung: SUMMARYThe effects of an altered rumen dilution rate (D) upon the molar proportions of volatile fatty acids (VFA) in rumen liquor, VFA production rate, microbial protein synthesis and carbohydrate digestion within the rumen were studied using adult wether sheep.Dilution rate and VFA proportions were unaltered by the infusion of up to 121 water/day into the rumen of sheep fed dried grass and concentrate (9:1). There was a small but significant (P 〈 0·05) increase in the rumen volume when the infusion rate was increased from 8 to 12 1/day.The intraruminal infusion of artificial saliva (41/day), or artificial saliva containing 4% or 8% w/v polyethylene glycol (PEG) caused a significant increase in D with an associated decline in the molar proportion of propionate (Pr) in the rumen liquor. A similar effect was obtained with the intraruminal infusion of 2·5% w/v sodium bicarbonate. The overall regression of Pr on D was highly significant: Pr = 32·5–82·1D; r = –0·99, P 〈 0·001.A diet of flaked maize: dried grass (6:4) was offered to three sheep each fitted with a rumen cannula and with a re-entrant cannula at the proximal duodenum. The intraruminal infusion (4 1/day) of artificial saliva containing 4% w/v PEG caused a significant (P 〈 0·01) increase in D and a significant (P 〈 0·01) depression in Pr in two animals. The dilution rate and Pr in the third animal were virtually unaltered by infusion. The regression of Pr on D for the three animals was highly significant: Pr = 34·8–136·8D; r = –0·98, P 〈 0·001. Each increase in D was associated with an increased flow of α-linked glucose polymer, total amino acids and total microbial amino acids into the small intestine and with an increased efficiency of microbial protein synthesis within the rumen.

Beschreibung: SUMMARYNineteen feedstuffs were evaluated for total digestible nutrients (TDN), digestible energy (DE) and metabolizable energy (ME) using growing pigs. DE values, on a drymatter basis, ranged from 1570 kcal/kg D.M. (grassmeal) to 4890 kcal/kg D.M. (BP Grangemouth protein). ME averaged 97·4% of DE for cereal feeds and 81·9% of DE for protein feeds, the ratio of DE to ME being significantly affected by the crudeprotein content of the feedstuff:ME/DE × 100 = 99·7–0·18 × crude protein (%): r = –0·94; P 〈 0·01.TDN was more closely related to ME than DE:DE (kcal/kg D.M.) = 45 TDN + 156: r = 0·92; P 〈 0·01,ME (kcal/kg D.M.) = 43 TDN + 71: r = 0·98; P 〈 0·01.ME values were corrected to both 30% and 0% nitrogen retention. Correction to 30% retention caused a maximum change of 3% in ME value while correction to 0% retention had a variable effect related to protein content of the feedstuff:(ME(N0)/ME) × 100 = 98·3–0·113 × crude protein (%): r = –0·80; P 〈 0·01.