Relationship between forage quality parameters and mineral intake in grazing beef cattle

One hundred ninety-two forage samples were collected over a 2-yr winter grazing season from cool-season pastures grazed by beef cattle (avg. BW = 294 kg) to determine the effects of periodicity and forage quality on mineral intake. Beef cattle minerals were offered to each pasture (n = 24 pastures)...

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Bibliographic Details
Published in:Journal of animal science 2016-10, Vol.94, p.107-108
Main Authors: Rivera, J D, Gipson, M L, Gipson, R G
Format: Article
Language:English
Subjects:
Beef
Beef cattle
Bovidae
Cattle
Correlation analysis
Data processing
Dietary minerals
Grazing
Minerals
Pasture
Pastures
Periodicity
Proteins
Sampling
Technology assessment
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Summary:One hundred ninety-two forage samples were collected over a 2-yr winter grazing season from cool-season pastures grazed by beef cattle (avg. BW = 294 kg) to determine the effects of periodicity and forage quality on mineral intake. Beef cattle minerals were offered to each pasture (n = 24 pastures) every 28 d from December through June. Refusals were weighed at the end of each interval, and forage samples were collected at the same time. Mineral refusals were used in conjunction with offered mineral to calculate mineral DMI. Forage samples were weighed and dried for 72 h at 50°C to determine DM; dried samples were analyzed using NIR technology to determine ADF and CP content. Data were analyzed to determine correlation (PROC CORR) of periodicity, CP, ADF, DM and mineral intake. As expected, as the season progressed, sampling period was highly correlated to forage quality (P < 0.01) with decreasing CP (r2 = -0.92), increasing ADF (r2 = 0.96) and DM (r2 = 0.80) associated with periods later in the grazing season. No effect (P = 0.25) of sampling period was observed for DMI of mineral. Average mineral intake through the grazing season was 81.6 g ± 1.7 g. Crude protein averaged 18.7% ± 8.4%; ADF averaged 31.3% ± 11.7%. Crude protein had no effect on mineral intake (P = 0.34). Acid detergent fiber tended to negatively correlate (P < 0.06; r2 = -0.14) with mineral DMI; greater mineral DMI was associated with lower ADF. Forage DM had a negative impact on mineral DMI (P = 0.001; r2 = -0.38); with greater forage DM associated with lower mineral DMI. Results suggest that mineral intake of beef cattle grazing cool-season forages is not affected by forage quality (ADF, CP), nor sampling period, but rather more likely affected by forage DM content.
ISSN:0021-8812
1525-3163