Comparative digestibility and digesta flow kinetics in two breeds of sheep

Abstract

A study was conducted to compare apparent digestibility and digesta flow kinetics in the whole digestive tract in two breeds of sheep (Churra and Merino) offered alfalfa hay at about maintenance. Ten mature sheep (five Churra and five Merino) each fitted with a rumen cannula were used in the study. Apparent digestibility was determined by total faecal collection. Liquid (Co-EDTA) and solid (Cr-mordanted fibre) markers were used to estimate rumen volumes and digesta flows. There were no significant differences between Churra and Merino sheep either in drymatter or fibre apparent digestibility (P > 0-05). Liquid and solid passage rates did not differ between breeds and the estimated total mean retention times were similar for both genotypes. The volume of liquid in the rumen was proportionately 0-14 greater in Churra than in Merino sheep, although the difference was not significant. Estimated saliva secretion was greater in Churra (11-6 (s.e. 0-77) I/day) than in Merino sheep (10-5 (s.e. 0-72) I/day) but the difference did not reach statistical significance. Solid contents of the rumen did not differ between breeds. Rumen particle density was lowest at 2 h after feeding and remained stable at other sampling times, with no significant differences between breeds. There were no significant differences between breeds in the urinary excretion of total purine derivatives but urinary excretion of allantoin and microbial nitrogen supply tended to be higher in Merino than in Churra sheep (P < 0-20). This was attributed to the smaller rumen pool size of Merino (8-0 (s.e. 0-62) kg) compared with Churra sheep (9-2 (s.e. 0-63) kg). The study indicated that there were no apparent breed differences between Churra and Merino sheep in digestibility and digesta passage when they were given a good-quality forage at a low level of intake.

Effect of genetic line on energy and nitrogen metabolism during late gestation in twin-pregnant ewes fed restrictedly

“…This result is in accordance with the fi nding of Ranilla et al (1998), who reported no breed differences between Churra and Merino sheep in DMD when fed a goodquality forage at a low level of intake. Furthermore, for sheep fed ad libitum genetic origin had no effect on DMD and organic matter digestibility (OMD) (Molina et al, 2001).…”

“…In order to improve performance and slaughter quality of sheep several breeding programmes have been carried out (Givens and Moss, 1994;Ranilla et al, 1998). In Denmark we have established 2 genetic lines of Shropshire ewes by mating for several generations either to a ram with high genetic potential for daily weight gain (Gain) or high slaughter quality (high muscle and low fat content, Lean).…”

Ruminal fermentation, microbial growth and amino acid flow in single-flow continuous culture fermenters fed a diet containing olive leaves

“…Flow through fermenters was maintained by continuous infusion of McDougall (1948) artificial saliva at a rate of 40 ml/h (5.33% dilution rate). The dilution rate was chosen to resemble the values found in sheep and goats fed similar diets (Ranilla et al., 1998; Yáñez‐Ruiz et al., 2004a). The effluent from each fermenter was collected into a vessel maintained in a 3 °C bath to prevent microbial growth and CO 2 was continuously infused into fermenters to keep anaerobic conditions.…”

A mechanistic model for predicting the nutrient requirements and feed biological values for sheep1

“…The coefficients for digestibility for DM, OM, NDF, and CP reported in 13 publications (Hogan and Weston, 1967;Robles et al, 1981;Prigge et al, 1984;Aitchison et al, 1986;Caton et al, 1988;Colucci et al, 1989;Wales et al, 1990;Di Francia et al, 1994;Torrent et al, 1994;Garcés-Yépez et al, 1997;Ranilla et al, 1998;Mulligan et al, 2001;Molina et al, 2001) were compared with the values estimated by the CNCPS-S. The evaluations were carried out using the information reported in the publications on FBW, feed intake, and composition as inputs in the CNCPS-S.…”