Table 2.

Abundance of mRNA associated with protein turnover from longissimus thoracis skeletal muscle of feedlot steers of different cattle breed types following implanting

Steers (n)	Implant and Breed Treatments1				SEM	P-values2
Gene3	AN-IMP	SG-IMP	AN-CON	SG-CON		Breed	Trt	B × T
	5	5	5	5
CAPN6
Day 2	53.46	15.35	21.77	151.92	42.26	0.29	0.24	0.07
Day 10	56.13	38.21	45.54	57.86	13.15	0.84	0.74	0.29
CAST
Day 2	49.79	30.25	42.17	28.00	7.83	0.05	0.52	0.72
Day 10	26.85	47.46	26.03	32.99	10.63	0.22	0.48	0.53
mTOR
Day 2	90.09	60.18	55.27	56.57	17.63	0.45	0.31	0.41
Day 10	56.77	60.02	38.94	74.59	17.31	0.31	0.93	0.39
MAPK
Day 2	22.84xy	21.71xy	16.50x	44.10y	7.87	0.10	0.28	0.05
Day 10	19.95	29.22	29.12	31.08	5.55	0.34	0.35	0.53
ATROG-1
Day 2	60.39	61.41	84.11	78.48	13.47	0.87	0.15	0.81
Day 10	64.75	89.25	81.69	96.44	18.82	0.32	0.53	0.79
MURF-1
Day 2	53.85	53.11	52.24	75.21	8.48	0.23	0.26	0.20
Day 10	73.79	70.19	98.02	105.61	16.05	0.91	0.09	0.74
FOXO3
Day 2	76.48	64.28	123.20	83.28	28.97	0.35	0.23	0.59
Day 10	55.37	71.68	65.61	86.27	17.21	0.26	0.41	0.88

Implant treatments administered on d 0 include: no implant +Angus (AN-CON), no implant + Santa Gertrudis (SG-CON), Revalor-S + Angus (AN-IMP; 120 mg trenbolone acetate + 24 mg estradiol) and Revalor-S + Santa Gertrudis (SG-IMP; 120 mg trenbolone acetate + 24 mg estradiol).

P-values indicate the effect of Breed, Treatment (TRT), or B × T (Breed × Treatment). Skeletal muscle biopsies were collected on day 2 and 10 post-implanting, and RNA isolation and quantitative PCR were performed as described in the Materials and Methods. All data are presented as the least square means ± SEM.

CAPN6, calpain 6; CAST, calpastatin; mTOR, mammalian target of rapamycin; MAPK, mitogen-activated kinase; ATROG1, atrogin 1; MURF1, muscle ring finger protein 1; FOXO3, forkhead box O3.

Different letters indicate a tendency between time points (0.05 < P ≤ 0.10).

Italics indicate P-values for the different effects (breed, trt and trtxbreed).