Stocking system effects on cattle performance, forage, and soil properties of cool-season pastures
Increasing stocking density and rotation frequency of grazing cattle may improve forage yield and quality and soil carbon content, but may reduce livestock performance and forage persistence and compact soil. Sixty mature August-calving Angus cows (Bos taurus L.; mean body weight (BW), 585 ± 9.9 kg) were allotted to six 4.05-ha cool-season pastures to graze by rotational (RS), strip (SS), or mob (MS) stocking from May through September for two years (2010-2011). Stocking density averaged 16 000, 80 000, and 350 000 kg BW * ha-1 * d-1 in RS, SS, and MS pastures, respectively. Daily live forage allowance was equal across treatments. Forage was offered as an entire paddock until 50% of the forage dry matter (DM) was removed or as strips either one or four times daily in RS, SS, and MS pastures, respectively. Stocking density did not significantly affect cow BW, body condition, or grazing selectivity; calf birth weight, average daily gain, or survival; forage mass, botanical composition, in vitro DM disappearance, or crude protein concentration; or soil moisture, carbon content, or water infiltration rate. Mean monthly forage disappearance was lower in RS than MS and SS pastures in May and June (month*treatment, P < 0.01); lower in RS than MS pastures in 2010, and lower in RS than SS and MS pastures in 2011 (year*treatment, P = 0.02). Soil bulk density tended to be lower in SS than RS pastures in July, but was greater in SS than RS pastures in October in both years (month*treatment, P = 0.07). Results demonstrate that in the first two years of implementation, increased stocking density with adequate forage allowance does not significantly affect cow or calf performance, forage mass or composition, or soil physical properties.