Feed intake, live mass-gain, body composition and protein deposition in pigs fed three protein levels

Abstract

A group of 82 genetically lean and 90 obese Landrace pigs was allotted to three dietary treatments with lysine concentrations of 1,22 (T1), 1,02 (T2) and 0,83% (T3), corresponding concentrations of crude protein (CP) of 19,7, 16,8 and 13,7% and digestible energy (DE) concentrations of 14,4; 14,2 and 14,0 MJ/kg diet. Diets were fed ad libitum from 8 weeks of age up to slaughter for whole body chemical analyses, at ± 20, ±30 or 90 kg live mass. Appropriate regression relationships were used to measure the effect of dietary protein level on the patterns of DE intake, daily gain and the deposition rates of protein (PDR) and fat (FDR) over the growth period 30-90 kg live mass. Dietary CP content had no significant effect on mean voluntary DE intakes and daily gains. DE intakes (MJ/d) for pigs from TI, T2, and T3 were 32,1; 32,2 and 32,8 respectively. Daily gains (g/d) were 737, 728 and 738 and DE: gain ratios were 43,8; 44,6 and 45,0 for the three treatments respectively. Obese pigs consumed highly significantly more DE than lean pigs (33,4 vs. 31,1 MJ/d), and also needed highly significantly more DE/kg gain (46,0 vs. 42,7 MJ), but they had similar daily gains (733 and 736 g/d). DE intake, daily gain, PDR and FDR followed curvilinear patterns. PDR curves peaked at ±56 kg live mass (51 kg for obese gilts and 64 kg for lean boars). Deposition rates increased from a mean of 106 g/d (93 g for obese gilts and 118 g for lean boars) to 124 g (103 g for obese gilts and 143 g for lean boars) at peak deposition, only to decline thcreafter to 105 g /d (85 g for obese gilts and 132 g for lean boars) at 90 kg live mass. A reduction of 15% in dietary protein content (T2) had no apparent effect on protein deposition. Pigs from T3, fed 30% less protein than pigs from T1, deposited only 2 g (1,9%) less protein /d at 32 kg live mass, 2 g (1,6%) less at maximum deposition and 2 g (1,9%) less at 90 kg live mass. 

Drie dieetbehandelings met lisienkonsentrasies van 1,22 (T1), 1.02 (T2) en 0,83% (T3), ooreenstemmende ruproteien- (RP)-konsentrasies van 19,7, 16,8 en 13,7% en verteerbare energie(VE)-konsentrasies van 14,4, 14,2 en 14,0 MJ/kg voer, is aan 'n groep van 82 geneties-maer en 90 vet Landrasvarke toegeken. Diete is ad libitum vanaf 8-wekeouderdom gevoer totdat die diere vir heel-liggaam chemiese samestelling, op ±20, ±30 of ±90 kg lewende massa geslag is. Paslike regressieverwantskappe is gebruik om die effek van dieetproteienpeil op die patrone van VEinname, daaglikse toename en die neerleggingstempo's van proteien (PDT) en vet (VDT) te meet oor die groeiperiode 30-90 kg lewende massa. Dieet RP-inhoud het geen betekenisvolle effek op gemiddelde vrywillige VE-innames en daaglikse toenames uitgeoefen nie. VE-innames (MJ/d) vir T1-, T2-, en T3-varke was 32,1; 32,2 en 32,8 onderskeidelik. Daaglikse toenames (g/d) was 737, 728 en 738 en VE: massatoename-verhoudings was 43,8, 44,6 en 45,0 vir die drie groepe onderskeidelik. Vet varke het hoogsbetekenisvol meer VE as maer varke ingeneem (33,4 teenoor 31,1 MJ/d), en het ook hoogsbetekenisvol meer VE/kg-toename (46,0 teenoor 42,7 MJ) benodig, maar het nie van maer varke verskil in massatoename nie (733 teenoor 736 g/d). VE-inname, daaglikse toename, PDT en VDT het kurwilineer verloop. PDT -kurwes het 'n piek op ±56 kg lewende massa (51 kg vir vet soggies en 64 kg vir maer soggies) bereik. Neerleggingstempo's het toegeneem vanaf 'n gemiddelde 106 g/d (93 g vir vet soggies en 118 g vir maer bere) tot 124 g (103 g vir vet soggies en 143 g vir maer bere) met piek-neerlegging, net om daama tot 105 g/d (85 g vir vet soggies en 132 g vir maer bere) op 90 kg lewende massa af te neem. 'n Verlaging van 15% in dieetproteieninhoud (T2) het geen beduidende effek op proteienneerlegging gehad nie. Groep T3-varke, wat 30% minder proteien as T1-varke gevoer is, het slegs 2 g (1,9%) minder proteien/d op 32 kg lewende massa neergele, 2 g (1,6%) minder met maksimum deponering en 2 g (1,9%) minder op 90 kg lewende massa. 

Keywords: Feed intake, growth rate, body composition, protein composition.