caa a22 4500 38806093X CHVBK 20180307125120.0 cr unu---uuuuu 161130e199810 xx s 000 0 eng 10.1017/S1357729800010122 doi S1357729800010122 pii (NATIONALLICENCE)cambridge-10.1017/S1357729800010122 Response to dietary protein during lactation of Meishan synthetic, Large White and Landrace gilts given food to achieve the same target backfat level at farrowing [Elektronische Daten] A 3 × 2 factorial experiment was used to investigate the influence of the breed type of gilts (Meishan synthetic 50% (M), purebred Large White (LW) and purebred Landrace (LR)) on response to insoenergetic diets of differing protein levels (180 g crude protein (CP) per kg, 9 g lysine per kg; or 240 g CP per kg, 12 g lysine per kg) offered to appetite over a 28-day lactation. Body fat reserves were adjusted during pregnancy by supplementing a set quantity of basal diet (131 g CP per kg, 12·7 MJ digestible energy (DE) per kg) with an energy source (maize starch + soya oil), to attain a backfat at P2 (6·5 mm off midline at last rib) of 25 mm at farrowing for all breeds. There were no significant diet effects or breed ×diet interactions on lactational performance. On day 1 of lactation, backfat was: M = 25·9, LW = 24·9, LR = 23·9 mm (P < 0·005). M gilts were lighter at farrowing (M = 173, LW = 192, LR = 182 kg; P < 0·001) and had more piglets than LW and LR. LR gilts had heavier piglets at birth (M = 1·13, LW = 1·18, LR = 1·38 kg, P < 0·001) than M and LW gilts. M gilts had a higher food intake (M = 6·4, LW = 5·2, LR = 5·1 kg/day; P < 0·001) but higher fat (M = 4·1, LW = 2·2, LR = 2·9 mm; P < 0·05) and weight (M = 15·9, LW = 1·0, LR = 4·7 kg; P < 0·001) loss over lactation than LW and LR gilts. LW gilts had a lower lactation output as reflected by lower litter weights at weaning than M and LR gilts (M = 73·7, LW = 59·3, LR = 75·2 kg; P < 0·002). It is concluded that lactation of gilts is not improved by provision of a very high protein diet (240 g CP per kg) and that performance still differs between breeds when backfat levels are standardized. Copyright © British Society of Animal Science 1998 backfat nationallicence gilts nationallicence lactation nationallicence pregnancy nationallicence protein intake nationallicence Sinclair A. G. Scottish Agricultural College, Craibstone Estate, Bucksburn, Aberdeen AB21 9YA Cia M. C. Pig Improvement Company, Fyfield Wick, Abington, Oxfordshire OX13 5NA Edwards S. A. Scottish Agricultural College, Craibstone Estate, Bucksburn, Aberdeen AB21 9YA Hoste S. Pig Improvement Company, Fyfield Wick, Abington, Oxfordshire OX13 5NA Animal Science Cambridge University Press 67/2(1998-10), 349-354 1357-7298 67:2<349 1998 67 ASC https://doi.org/10.1017/S1357729800010122 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1017/S1357729800010122 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Sinclair A. G. Scottish Agricultural College, Craibstone Estate, Bucksburn, Aberdeen AB21 9YA NATIONALLICENCE 700 1- Cia M. C. Pig Improvement Company, Fyfield Wick, Abington, Oxfordshire OX13 5NA NATIONALLICENCE 700 1- Edwards S. A. Scottish Agricultural College, Craibstone Estate, Bucksburn, Aberdeen AB21 9YA NATIONALLICENCE 700 1- Hoste S. Pig Improvement Company, Fyfield Wick, Abington, Oxfordshire OX13 5NA NATIONALLICENCE 773 0- Animal Science Cambridge University Press 67/2(1998-10), 349-354 1357-7298 67:2<349 1998 67 ASC CC0 http://creativecommons.org/publicdomain/zero/1.0 nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-cambridge