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The importance of a dam’s early-gestation nutrition, both for the short and long term, is drawing a lot more attention.
Early gestation is when the placenta, which carries nutrients to the fetus, develops; it’s also when the vital organs develop.
What’s more, the effects on calves of nutrient-deprived cows were long-lasting. Though they seemed normal at birth, these calves weren’t as able to remain healthy or perform optimally.
Early-deprived fetuses – even though equalized in weight with fetuses of control cows – had half the normal number of nephrons in their kidneys. Nephrons are important because they help remove toxins and metabolites from the blood for excretion, Ford explains.
“Once these animals enter the feedlot and go on full feed, their kidneys aren’t functioning fully and can’t filter out toxins efficiently. This affects their growth rate and health,” he says.
The researchers also saw decreases in skeletal muscle mass in nutrient-deprived offspring as they grew, as well as increases in adipose (fat) tissue. Early fetal malnutrition seemed to shift carcass characteristics to fatty and less lean.
“Most people have heard about genotype and DNA, and that a particular set of genes makes an animal what it is. But, it’s been determined recently that the intrauterine environment can alter gene expression patterns of an animal after birth, a process called epigenetics. These changes in gene expression alter the phenotype of an animal and thus its quality,” Ford explains.
So, even though two animals may have identical genotype, if gestated in females on different nutritional regimens, they turn out different.
“They may look the same at birth but, once in the feedlot, one may get sick and the other may not. Life doesn’t begin at birth. The animal undergoes many more changes before birth than it ever will after birth,” Ford says. “If we don’t enable the fetus to develop optimally and express normal patterns of organ and tissue development, we alter the composition and quality of those organs. No matter what is done to the animal after it’s born, we can’t fully correct this early damage.”
Thrifty phenotype & obesity
If the normal nutritional requirements of cattle and sheep are maintained after birth, many of these concerns won’t be noticed,” Ford says. “It’s when we start feeding them all they will eat, that we see problems.”
The biggest effect in response to their under-nutrition environment is increased appetite. With access to full feed, they eat more, which can result in health problems because they’re prone to insulin resistance and obesity, Ford says, something borne out by his work with sheep.
“Adult offspring from undernourished ewes spend the same amount of time at the feed bunk, but eat significantly more. Utilizing a Grow-Safe computerized feed measurement system, we measured how long and how much they ate. These animals ate for the same amount of time as other animals but consumed 50% more feed. There was no resulting increase in feed efficiency, however; they just put on more fat, both internal and subcutaneous.”
“You can imagine how this affects them in a feedlot. We don’t know yet how these problems might affect cows in a breeding herd,” Ford says.
That body memory remains with an animal or person throughout life. The body tries to gain weight whenever it has the opportunity. Predisposition to increased appetite and fat tissue is linked to thrifty phenotype.
“Fetuses deprived of nutrients in utero expect to be born into an environment short of food. They consume and accumulate significantly more nutrients as fat than do control offspring when exposed to unlimited food. Their body is programmed to accumulate and store nutrients whenever available,” Ford explains.
Pregnant cows should be maintained in a range of normality. Under-nutrition during drought can be a problem. It’s also a problem if you overfeed pregnant heifers, or bought pregnant heifers from a feedlot, he says.