Comparison of voluntary food intake, apparent digestibility, digesta kinetics and digestive tract content in Manchega and Lacaune dairy sheep in late pregnancy and early and mid lactation

Abstract

Two experiments were carried out with pregnant (experiment 1) and lactating ewes (experiment 2), to compare dry-matter (DM) intake, and total tract apparent digestibility, digesta kinetics and weight of digestive tract contents of Lacaune and Manchega sheep, with the aim of explaining possible differences between the breeds in voluntary food intake. In experiment 1, 20 3-year-old single-bearing pregnant ewes, 10 Manchega and 10 Lacaune, were permanently housed for the last 10 weeks of pregnancy. The diet used consisted of lucerne hay, offered ad libitum, supplemented with 0·3 kg/day of concentrate. DM and digestible DM intake per kg M0·75 were higher (P < 0·01) in Lacaune than in Manchega sheep. Breed did not affect total tract apparent digestibility, fractional rates of passage, transit time, total mean retention time, or weight of digestive tract contents. Changes in body weight and body condition score were similar between breeds. In contrast, Lacaune lambs tended (P = 0·09) to weigh less than Manchega lambs, suggesting genetic differences in the energy utilization between breeds in late pregnancy. Higher DM intake observed in Lacaune sheep may have been related to a higher energy demand for mammary development. In experiment 2, 32 3-year-old lactating multiparous ewes, 16 Manchega and 16 Lacaune, were permanently housed during the first 12 weeks of lactation. The experimental diet used was based on a mixture of maize silage and dehydrated lucerne (10: 1, fresh weight basis), offered ad libitum, and supplemented with 0·8 kg/day of concentrate. Milk, fat and protein yield as well as DM and digestible DM intake in Lacaune ewes was higher (P < 0·01) than in Manchega ewes. DM intake was constant in Lacaune sheep with advancing lactation, while in Manchega sheep DM intake decreased. Throughout this period Lacaune ewes lost 0·5 kg of body weight while Manchega gained 4·4 kg. Breed did not affect either apparent digestibility of DM, organic matter and neutral-detergent fibre, or fractional rates of passage, transit time and total mean retention time. The weight of total tract digestive contents was greater (P < 0·05) in Lacaune than in Manchega sheep, particularly in the reticulo-rumen. Results suggest that the scheme of selection in Lacaune dairy sheep has increased milk yield together with voluntary food intake, the latter being associated with an increase in the rumen fill capacity. The higher milk yield of Lacaune ewes cannot be attributed to the higher DM intake only; other factors, i.e. mobilization of fat reserves, are required to support this higher milk output.

Performance of dairy ewes fed diets with a fibrolytic enzyme product included in the concentrate during the suckling period

“…Values observed for DM intake reached 4.3% of BW and were greater than those reported by Molina et al (2001) in Manchega and Lacaune dairy ewes for similar milk yield and exploitation conditions. Despite the differences in estimated milk yield between the two breeds (0.52 l/day; P , 0.001), no DM intake differences between them were detected during suckling, as also reported by Molina et al (2001). An initial decrease in DM intake in all ewe groups was observed between weeks 1 and 2, most probably due to the adaptation of the ewes to the lactation diet and to a compensatory intake after parturition.…”

“…Moreover, Lacaune ewes Flores, Caja, Casals, Albanell and Such were 30% (P , 0.01) more efficient than Manchega ewes, transforming feed into milk during the suckling period (Table 3) as a consequence of their greater milk yield for a similar DM intake as observed in dairy sheep during milking by Molina et al (2001) and Marie et al (2002).…”

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.…”

“…The SBW reported in six publications (Manfredini et al, 1987;Wales et al, 1990;Fonseca et al, 1998;Krü ger, 1999;Molina et al, 2001) were compared with the values estimated by the CNCPS-S. The predicted gain or losses of FBW reflect the model prediction of energy balance.…”

“…The predicted gain or losses of FBW reflect the model prediction of energy balance. Four publications (Manfredini et al, 1987;Krü ger, 1999;Molina et al, 2001), for a total of 13 treatments, reported experiments conducted with lactating ewes, whereas in the other two publications (Wales et al, 1990;Fonseca et al, 1998), for a total of 16 treatments, mature ewes and wethers were used. The evaluations were conducted using the information reported in the publications on SBW, feed intake and composition, milk yield and composition as input into the CNCPS-S, following the same procedure previously described for the validation of feed digestibility.…”