Effect of dietary supplementation or cessation of magnesium-based alkalizers on milk fat output in dairy cows under milk fat depression conditions

Abstract

We aimed to evaluate the effects of dietary supplementation with magnesium oxide and calcium-magnesium dolomite on milk fat synthesis and milk fatty acid profile or persistency in milk fat synthesis after their cessation in dairy cows under milk fat depression conditions. Twenty-four multiparous dairy cows in early lactation (mean ± standard deviation; 112 ± 14 d in milk) were used in a randomized complete block design. Milk fat depression was induced in all cows for 10 d by feeding a diet containing 35.2% starch, 28.7% neutral detergent fiber, and 4.8% total fatty acid (dry matter). The experiment was conducted in 2 periods. During the Mg-supplementation period (d 1-20), cows were randomly assigned to (1) the milk fat depression diet used during the induction phase (control; n = 8), (2) the control diet plus 0.4% magnesium oxide (MG; n = 8), or (3) the control diet plus 0.8% calcium-magnesium dolomite (CMC; n = 8). Compared with the control group, feeding the magnesium-supplemented diets increased milk fat concentration and yield by 12% within 4 d. During the 20-d Mg-supplementation period, both the MG and CMC diets increased milk fat concentration and yield, as well as 3.5% fat-corrected milk and energy-corrected milk yield, without affecting dry matter intake, milk yield, and milk protein and lactose concentrations. In the Mg-cessation period (d 21-30), all cows received the control diet, which resulted in a greater milk fat concentration and yield in the cows that had already received the MG and CMC diets in the Mg-supplementation period. Whereas, milk fat concentration and yield remained high after discontinuation of the magnesium-containing alkalizer until d 27. The difference in milk fat synthesis was associated with lower trans-10 C18:1 (−22%) and higher trans-11 C18:1 (+12.5%) concentrations in milk during the Mg-supplementation period. Furthermore, it was evident that within 2 d of supplementation, the trans -10: trans -11 ratio was lower in MG and CMC cows compared with cows receiving the control. This suggested that the effect of magnesium-based alkalizers on milk fat synthesis was mediated via a shift in ruminal biohydrogenation of cis-9,cis-12 C18:2 in the rumen. In conclusion, abrupt addition of magnesium oxide and calcium-magnesium dolomite increased milk fat synthesis, which persisted for 7 d after cessation of magnesium-based alkalizers. A similar ability to recover milk fat synthesis and normal fatty acid biohydrogenation pathways was observed for magnesium oxide and calcium-magnesium dolomite.

Effect of a High-Starch or a High-Fat Diet on the Milk Performance, Apparent Nutrient Digestibility, Hindgut Fermentation Parameters and Microbiota of Lactating Cows

“…In this study, milk fat concentration and yield in cows fed the IS and IO diets were consistent with cows in the MFD condition. In this trial, DMI and milk yield did not differ significantly between different dietary treatments; these results are similar to other studies [21,22]. Milk fat yield and concentration were significantly decreased, while the rest of milk components and yield did not change significantly, similar to what some other researchers have found [23,24].…”

La suplementación mineral del ganado: Revisión de principios y tecnologías aplicadas, para mejorar el desempeño productivo

“…El uso de los búferes ruminales evidenció un gran interés desde finales de los años 70 (Edman, 1978;citado por Weiss, 2017). Es bien conocido el rol del sodio en los procesos osmoreguladores (Balance Anión-Catión; BAC y el diferencial Anión Catión; BCAD) y de los alcalinizantes, por su efecto búfer (bicarbonato y sesquicarbonato de sodio) que se relacionan con: el consumo de materia seca (Khelil-Arfa et al, 2013), la eficiencia alimenticia, la recuperación ante problemas de depresión de la grasa láctea (Razzaghi et al, 2021), procesos de resiliencia y como coadyuvante, en presencia del estrés calórico (Opgenorth et al, 2020). Desde 1974 los estudios evidenciaron la relevancia de las dietas aniónicas (BCAD, cercano a cero o negativo), sobre las enfermedades metabólicas del postparto.…”