I don't think it will be hard to keep his weight up so long as he can eat the grain.
1	I	I	PRON	PRP	Case=Nom|Number=Sing|Person=1|PronType=Prs	4	nsubj	4:nsubj	_
2-3	don't	_	_	_	_	_	_	_	_
2	do	do	AUX	VBP	Mood=Ind|Number=Sing|Person=1|Tense=Pres|VerbForm=Fin	4	aux	4:aux	_
3	n't	not	PART	RB	_	4	advmod	4:advmod	_
4	think	think	VERB	VB	VerbForm=Inf	0	root	0:root	_
5	it	it	PRON	PRP	Case=Nom|Gender=Neut|Number=Sing|Person=3|PronType=Prs	8	expl	8:expl	_
6	will	will	AUX	MD	VerbForm=Fin	8	aux	8:aux	_
7	be	be	AUX	VB	VerbForm=Inf	8	cop	8:cop	_
8	hard	hard	ADJ	JJ	Degree=Pos	4	ccomp	4:ccomp	_
9	to	to	PART	TO	_	10	mark	10:mark	_
10	keep	keep	VERB	VB	VerbForm=Inf	8	csubj	8:csubj	_
11	his	his	PRON	PRP$	Case=Gen|Gender=Masc|Number=Sing|Person=3|Poss=Yes|PronType=Prs	12	nmod:poss	12:nmod:poss	_
12	weight	weight	NOUN	NN	Number=Sing	10	obj	10:obj	_
13	up	up	ADV	RB	_	10	advmod	10:advmod	_
14	so	so	ADV	RB	_	15	advmod	15:advmod	_
15	long	long	ADV	RB	Degree=Pos	4	advmod	4:advmod	_
16	as	as	SCONJ	IN	_	19	mark	19:mark	_
17	he	he	PRON	PRP	Case=Nom|Gender=Masc|Number=Sing|Person=3|PronType=Prs	19	nsubj	19:nsubj	_
18	can	can	AUX	MD	VerbForm=Fin	19	aux	19:aux	_
19	eat	eat	VERB	VB	VerbForm=Inf	15	advcl	15:advcl:as	_
20	the	the	DET	DT	Definite=Def|PronType=Art	21	det	21:det	_
21	grain	grain	NOUN	NN	Number=Sing	19	obj	19:obj	SpaceAfter=No
22	.	.	PUNCT	.	_	4	punct	4:punct	_
