Two Holstein heifers portrait

High water sulfates affect intake and growth in heifers

Alvaro Garcia

High quality drinking water is indispensable for livestock to express their genetic potential for production. Its availability determines critical bodily functions besides hydration, including promotion of dry matter intake, maintaining osmotic balance, excretion of waste products, and cooling the organism during hot weather among other. Water however can also be a carrier of other elements that are not required and can be even toxic to the animal.

There have been countless research experiments that explored nutrient excesses, deficiencies, and toxicities that can be triggered by inadequate water quality. One typical case has been water with an excess of sulfur which can lead to polioencephalomalacia in calves, diarrhea, impaired growth and reproduction, and other non-specific health issues. Most of these issues usually occur when cattle are offered well water or drink from ponds in areas that are rich in sulfur.

Feeding too much sulfur can interfere with the absorption of copper and selenium

About 0.15% of body weight of cattle is sulfur. It is found in methionine, cysteine, cystine, homocysteine, and taurine; in chondroitin sulfate of cartilage; and in the B-vitamins thiamin and biotin. Methionine, thiamin, and biotin cannot be synthesized in cattle tissues, so they must be supplied in the diet or synthesized by ruminal microbes. The sulfur content of most feed sources reflects the sulfur amino acid content of the proteins in the feed.

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Using polyhalite as an acidogenic ingredient in close-up diets

Using polyhalite as an acidogenic ingredient in close-up diets

Ishaya U. Gadzama & Fernando Díaz

At calving, calcium requirements are quadrupled, which results in cows experiencing variable degrees of subclinical to clinical hypocalcemia. To improve calcium mobilization, Goff and Horst (1997) suggested to generate a light metabolic acidosis by modifying the equilibrium between anions and cations (Na+K)-(Cl+S) in the diet. Feeding polyhalite mineral as an acidogenic ingredient has been proposed to reduce urine pH in close-up dairy cows.

Polyhalite is a natural mineral formed where sea water has been concentrated and exposed to prolonged evaporation. Polyhalite in Greek means “many salts”, and is a hydrated sulfate of potassium, calcium, and magnesium. Polyhalite contains four important minerals:

  • 48% SO3
  • 17% CaO
  • 14% K2O
  • 6% MgO

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Hypophosphatemia during the transition period

Hypophosphatemia during the transition period

Fernando Diaz

Phosphorus is an essential macromineral involved in several biological processes such as bone mineralization, energy transition, and acid-base buffer systems. During lactation, the NRC 2001 guidelines recommends to feed diets with 0.3 – 0.4% of phosphorus in a dry matter (DM) basis.

In general, in intensive dairy production systems, feeding feed ingredients with medium (cereal and cereal co-products) and high concentration of phosphorus (soybean meal) is normally enough to meet cow’s phosphorus requirement, thus, it is not necessary to supplement mineral phosphorous (phosphates).

Nonetheless, cow phosphorous requirement during the last trimester of gestation increases drastically. It has been reported that phosphorus accretion in fetus (fetal fluids and membranes) and uterine tissues increases from 1.9g/day at 190 to 5.4g/d at 280 days of gestation, respectively. For this reason, phosphorus deficiency and hypophosphatemia incidence in dairy cows are more common during the transition period.

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Importance of selenium source under heat stress conditions

Importance of selenium source under heat stress conditions

Fernando Díaz

Selenium is an essential trace mineral that is an indispensable component of the antioxidant system. Selenium is an essential element of antioxidant enzymes such as glutathione peroxidase, and its deficiency may result in an imbalance of redox homeostasis and ultimately oxidative stress.

Since selenium content in plants is highly variable, selenium is normally supplemented in dairy cow diets using inorganic sources (sodium selenite, sodium selenate), organic sources (selenium yeast, hydroxy-selenomethionine) or a combination of both. Ruminal metabolism and intestinal absorption of these selenium compounds differ as well as their antioxidant capacity.

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