"...the consumption of beef and lamb fell dramatically to approximately 100 grams and 55 grams respectively. The consumption of fish also..."

[hardyweineberg]

"...the consumption of beef and lamb fell dramatically to approximately 100 grams and 55 grams respectively. The consumption of fish also declined, but much less significantly to just below 50 grams..."
Source: Cambridge IELTS 8; AN IELTS examiner most likely wrote the sentences.

The use of "but" appears not to be in line with grammar rules. It was used to show the contrast between the sentence in which it was and the preceeding sentence.

So, if the 2nd sentence is correct, does it mean I can make sentences like these: "The proportions of A and B reduced slightly over the period. (And) the proportion of C also declined, but it declined significantly to..."; "The proportions of A and B reduced slightly over the period. And the proportion of C also declined, though dramatically, to..."; "The proportions of A and B reduced slightly over the period. (And) the proportion of C also declined, but it did so significantly to..."?

 

[5jj]

The use of "but" appears not to be in line with grammar rules.

It looks OK to me. What to you think is wrong with it?

 

[hardyweineberg]

It looks OK to me. What to you think is wrong with it?

"Sentence 1. Sentence 2, but + sentence 3."

In the sentence, the clause with "but" (sentence 3) doesn't contrast with the one immediately preceding it (sentence 2), but rather with a distant sentence ( sentence 1).

"But" is normally used to introduce a statement that contrasts with what was "just" said or written.

 

[Tarheel]

The sentence is unremarkable. What would you put there instead?

(50 grams is not much less than 55.)