Production, physiological response, and calcium and magnesium balance of lactating Holstein cows fed different sources of supplemental magnesium with or without ruminal buffer
artículo original
Fecha
2023Autor
Lobo, Richard Roberto
Arce Cordero, José Alberto
Sarong, So
Soltis, Macey P.
Nehme Marinho, Mariana
Agustinho, Bruna Calvo
Ravelo, Anay D.
Vinyard, James R.
Johnson, Mikayla L.
Monteiro, Hugo Fernando
Sarmikasoglou, Efstathios
Faciola, Antonio Pinheiro
Metadatos
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The objective of this study was to evaluate the effects
of dietary replacement of magnesium oxide (MgO) with
calcium-magnesium hydroxide [CaMg(OH)2] and its interaction with ruminal buffer (sodium sesquicarbonate)
supplementation on production, Ca and Mg balance,
and overall physiological response of mid-lactation Holstein dairy cows. Sixty cows averaging 40.5 ± 7.0 kg of
milk/d were used. Treatments were assigned following
a 2 × 2 factorial arrangement: (1) MgO, (2) MgO +
buffer, (3) CaMg(OH)2, or (4) CaMg(OH)2 + buffer.
Diets were formulated to have 16.5% of crude protein,
1.82 Mcal/kg of net energy for lactation, 0.67% Ca,
0.39% P, and 0.25% Mg, all on a dry matter (DM)
basis. Treatments were individually top dressed. Milk
production, composition, and DM intake were evaluated. A subsample of 20 cows were randomly selected
for the evaluation of Ca and Mg balance, blood gases,
and electrolytes. Ruminal fluid was also collected for
evaluation of pH and Ca and Mg solubility. Effects of
Mg source, buffer, and the interaction Mg source ×
buffer were analyzed through orthogonal contrasts. An
interaction of Mg source × buffer was found for DM intake and feed efficiency, in which cows fed CaMg(OH)2
had a similar feed efficiency regardless of ruminal buffer inclusion; however, when cows were fed MgO, the
inclusion of buffer reduced feed efficiency. No effects
on body weight and milk yield were observed. Buffer addition tended to increase the concentrations of fat,
protein, and solids-not-fat, without affecting the yields
of these milk components. Magnesium source and buffer did not affect ruminal fluid, blood, urine, or fecal
pH; however, buffer supplementation increased urinary
pH. Treatment with CaMg(OH)2 increased blood concentration of HCO3
−, total CO2, and base excess compared with cows fed MgO. No differences were observed
in the ruminal solubility of Ca and Mg or on milk or
urinary Ca and Mg excretion. Greater plasma Mg concentration was observed for animals fed MgO compared
with cows fed CaMg(OH)2; however, both sources were
above the threshold recommended in the literature for
dairy cows. Also, a reduction in fecal Mg excretion was
observed in animals fed CaMg(OH)2. In summary, we
provide evidence that CaMg(OH)2 could replace MgO
without affecting performance, overall physiological
response, or Ca and Mg balance of mid-lactating dairy
Holstein cows.
External link to the item
10.3168/jds.2022-22583Colecciones
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