Table 1 Studies reporting vitamin A restriction and marbling or intramuscular fat (IMF) in cattle
Breed type | Treatment | General results/conclusions | Reference |
|---|---|---|---|
Japanese Black steers | Backgrounded at about 20,000 IU vitamin A/day, low vitamin A (no extra supplementation) diet was fed from 15 to 23 months of age | Maintaining a low level of serum vitamin A (≤ 20 μg/dL) before 23 months of age may contribute to higher marbling scores | [6] |
Black yearling steers | Backgrounded at 1364 IU vitamin A/kg DM, then 0, 1103, 2205, 4410, or 8820 IU supplemental vitamin/kg DM was fed for 142 or 143 days | Little effect was observed for performance, marbling, or lipogenic enzyme activity in adipose tissue | [8] |
Korean native steers | Backgrounded at 8890 IU vitamin A/kg DM, then 8890 (Con), 3890 (T1), or 890 (T2) IU restricted vitamin A/kg DM was fed for 240 days | Marbling scores in the vitamin A-restricted groups were not significantly higher than in the control group but showed a trend for a higher yield grade | [9] |
Feedlot heifers | Backgrounded at 3640 IU vitamin A/kg DM, then 3640 or 0 IU vitamin A/kg DM was fed for 218 days | Vitamin A restriction increased the degree of marbling without affecting backfat thickness | [60] |
Holstein steers | Backgrounded at 2700 IU vitamin A/kg DM, then 2200 or 950 IU of vitamin A/kg DM was fed for 112 days or 243 days (2200 IU for 112 days and 950 IU for latter 131 days) | Feeding the restricted vitamin A 243 days increased IMF without affecting subcutaneous or visceral fat deposition | [61] |
Feedlot heifers | Backgrounded at < 1300 IU vitamin A/kg DM, then 0 or 2700 IU supplemental vitamin A/kg DM was fed for 168 days | The percentage of carcasses grading ≥ Choice−was not different between treatment groups | [62] |
Feedlot heifers | Backgrounded at < 1100 IU vitamin A/kg DM, then 0 or 2700 IU supplemental vitamin A/kg DM was fed for 112 or 227 days | Vitamin A restriction did not affect USDA yield grade or marbling score | [63] |
Angus steers | Backgrounded at a low β-carotene and vitamin A cereal-based ration (no detailed data), then 0 or 60,000 IU supplemental vitamin A/100 kg of BW/day was fed for 308 days | There was greater IMF in longissimus thoracis et lumborum and greater seam fat, but there ws no significant change in marbling score | [64] |