Influence of growth conditions on the value of crisphead lettuce. 3. Protein quality and energy density as determined in balance experiments with rats.
Crisphead lettuce was cultivated under different growth conditions. Sixteen batches differed in time of planting (early and late), total nitrogen supply (200 kg N/ha, 150 kg N/ha, 100 kg N/ha, 50 kg N/ha) and time of harvest (early and late). Based on chemical analysis and balance studies on rats the nutritive value of each 16 batches was determined. The protein content increased progressively from 16.00 to 19.88% with fertilization level. This increase in protein caused a significant drop in essential amino acids (g/16 g N) demonstrating a lower biological value of this protein. Early planting or early harvest resulted in a higher protein content than in lettuce of late planting or late harvest. Total dietary fibre content was approximately 25% of DM-and this value was not much influenced by the different growth conditions. Soluble dietary fibre was approximately 20-25% of total dietary fibre. Due to the high fibre content, energy digestibility was relatively low. The contents of Cd and Pb were below what is considered as 'acceptable' levels.
National Institute of Animal Science, Research Center Foulum, Tjele, Denmark.
G
G
Brunsgaard
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U
Kidmose
J N
JN
Sørensen
K
K
Kaack
B O
BO
Eggum
D000383:Agriculture / Q000379:methods*; D000596:Amino Acids / Q000032:analysis*; D000704:Analysis of Variance; D000818:Animals; D004043:Dietary Fiber / Q000032:analysis; D004063:Digestion; D002149:Energy Intake; D005308:Fertilizers; D018545:Lactuca / Q000737:chemistry*; D008297:Male; D009566:Nitrates; D009753:Nutritive Value; D014674:Plant Proteins, Dietary / Q000032:analysis* / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D013997:Time Factors
D000596:Amino Acids; D004043:Dietary Fiber; D005308:Fertilizers; D009566:Nitrates; D014674:Plant Proteins, Dietary