by feeding two corn-soybean meal based diets, supplement- ed either with 0.13% L-Met or 0.13% DL-Met on equimolar basis on growth performance and myogenesis-related gene expression of 21-48 kg growing pigs (ten pigs per diet) for four weeks. There were no differences (P>0.50) in average daily gain (ADG), average daily feed intake (ADFI) or gain:feed among pigs fed diets supplemented with L-Met or DL-Met (see Figure 1).
Table 2 – Gut morphology of duo- denum and jejunum and relative mRNA abundance of tight junction proteins in jejunum of piglets fed diets supplemented with DL‐Met or L‐Met.
Treatment Parameter
Villi height:crypt depth ratio Duodenum Jejunum
L-Met DL-Met 2.46 P-value
2.2 2.1 0.18 2.5
mRNA abundance of tight junction proteins in jejunum Claudin 3 Occludin
Zona occludens 1 Source: Zeitz and others (2019).
1 1 1
0.84 0.72 0.74
0.78
0.32 0.08 0.1
They also found no differences (P>0.25) among pigs fed the two diets in expression of mRNA for selected myogenesis-re- lated genes, such as myogenic differentiation 1, myogenin, myogenic factors 5, and myocyte enhancer factors 2A and 2C in longissimus dorsi muscle (see Table 1). Similar gene expres- sion levels indicate that there was no difference between L-Met and DL-Met in terms of their effects on the muscle de- velopment of growing pigs. Also in 2019, researchers from the University of Giessen, Ger- many (Zeitz and others) assigned 11-15 kg weaned pigs to six wheat-barley based diets supplemented either with 0.067%,
Amongst others, the amino acid methionine is important for pigs to achieve an optimum growth performance. PHOTO: HENK RISWICK
Figure 2 - Bioavailability of L-Met relative to DL-Met based on body weight gain and feed:gain ratio of weaned piglets fed diets supplemented with DL‐Met (DL) or L-Met (L) for three weeks. 7.0
1.0 2.0 3.0 4.0 5.0 6.0 7.0
0.0
DL (x1) L (x2)
Bioefficiency: DL = 100 % L = 99.7 %
0.00 0.10 0.20 y = –7.36+(56.07·x1 + 55.91·x2)
Source: Zeitz and others (2019). ▶PIG PROGRESS | Volume 35, No. 6, 2019 27
4.0 5.0 6.0
1.0 2.0 3.0
0.0 0.30 0.40 Supplemented methionine, % of diet
DL (x1) L (x2)
Bioefficiency: DL = 100 % L = 99.8 %
0.00 0.10 0.20
y = 6429.8–6427.8·(1–e–(47.65·x1+47.56·x2)) 0.30 0.40
Supplemented methionine, % of diet
Gain, kg
feed:gain ratio
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