Neonatal Mortality in Kids
There are many causes of death of late-term fetuses, newborns and young kids. Deaths in the last month of gestation until a month after delivery are chronologically categorized as abortion, stillbirth and neonatal mortality, depending on when they occur.
Some people don't know how many kids they lose because they do not keep records. Just because it isn't written down doesn't mean that it didn't happen. Accurate records give a true picture that can help identify problems, establish goals and make management improvements. The number of fetuses born dead or that die within 24 hours after birth usually indicate the quality of herd management and the level of the goatkeeper's experience. Attending each birth and giving timely assistance when problems occur greatly increases the likelihood of getting live kids. Ideally, stillbirths and mortalities up to 24 hours after birth should be under 2%. Preweaning death rates up to a month of age should be under 5%. Higher death rates than these may indicate significant management failures.
Abortion is the expulsion of fetuses less than full term that are incapable of independent life. In cattle, 90% of all abortions are caused by viral or bacterial infections. Some infected fetuses survive to term but die within a few days. A veterinarian's help is needed to investigate the cause of abortion. S/he should submit all or parts of the fetus and placenta, plus the mother's blood drawn at the time of the abortion and 10-14 days later. Infectious organisms can often be cultured, but abortion diagnosis may only be successful up to 40% of the time. Labs cannot diagnose non-infectious causes, including genetic defects, maternal heat stress, maternal endotoxemia, toxins or inherent biochemical abnormalities.
Most infections that cause disease and death in very young kids are acquired from the environment at or shortly after birth. Mothers are more susceptible to disease, including those that cause abortion, and higher worm burdens during pregnancy due to immunosuppression caused by the production of progesterone. Some abortions may be the result of pre-existing infections made worse by suppression of the immune system, stress or mineral deficiencies. Work with a veterinarian to diagnose abortion and to correct the causes that contribute to it.
Congenital defects are structural abnormalities existing at birth, although they may not be obvious. There are many different kinds of birth defects. Genetic defects run in families and may spread due to selection practices. Certain plants, drugs, chemicals, viruses and bacteria can cause deformities. Environmental influences do not run in families, although they may be present on the same farm or in the same general area. Producers need a veterinarian's help to identify the causes of birth defects. Necropsies are useful in finding internal defects, such as organ abnormalities, that have no obvious outward signs.
Dystocia Risk Factors
Dystocia is defined as any birth that requires assistance, reduces the offspring's viability or causes maternal injury. The owner's ability to recognize problems and either assist or summon help is a prime factor in successful live births. Helping early in a difficult situation results in more survivors.
Of all calf deaths, 64% between birth and weaning age occur during the first four days of life. Of this number, 66% are attributed to dystocia. These figures do not include stillbirths arising during dystocia which would raise the death percentage much higher. Litter-bearing, first-time mothers lose up to 12% more offspring than experienced mothers, with higher losses occurring in larger litters. In large litters, there is more opportunity for malpresentation and entanglement which will dealy or prevent kids coming out by themselves.
In cattle, fetal birth weight and fetopelvic disproportion is the primary factor in dystocia, and abnormal presentation is secondary. Genetic and environmental factors contribute to birth weight. Each parent contributes 50% of the fetus' genes. But the mother also provides the fetal environment, so her influence on birth weight is the greatest. Maternal environment includes: age, breed, size, pelvic dimensions, and nutrition, including quantity and quality of the diet and trace mineral availability.
Both thin and fat mothers experience more dystocia; their offspring have less vigor and higher death rates. Body condition scoring plays an important role in evaluating maternal nutrition.
The sire has a dramatic effect on birth weight. Birth weight is a moderately heritable trait at 30% to 45% in cattle and 30% in lambs. Significant genetic progress can be made in improving birth weights by using males that produce young of a small to normal size but that grow to the same size at maturity.
Using a sire extensively because he excels in low birth weight can mean trouble later. A bull who was his breed's calving ease trait leader for many years produced offspring that were small at birth, at weaning, as yearlings and as adults. His daughters had increased dystocia rates because they were small. This EPD value became evident in the bull's maternal calving ease category. Producers should consider important maternal traits in addition to the sire's birthing ease.
The best predictors of potential birthing ease and birth weight estimates come from using EPD (Estimated Progeny Difference) scores as a selection tool. EPDs, based on measurable traits, are computed using complex genetic and environmental variables from records on individual sires, dams and many relatives. Heritability estimates for a sire's direct and maternal calving ease in the Simmental Sire Summary are 18% and 19%, respectively. Other associations' Sire Summaries include calving ease categories to help breeders identify appropriate sires for making lasting genetic progress in this trait. Without these statistics, the best way to evaluate an sire's potential for birth weights is to know his and those of his parents and all his grandparents.
Cross-breeding large breed males to small breed females (and vice-versa) in cattle, sheep and horses has produced interesting results. Instead of having offspring sized halfway between the parental extremes, small breed females delivered slightly larger offspring than usual for her breed. Also, gestation length was several days shorter than normal, probably due to less uterine space and reduced placental nutrition and placental size. Large breed females delivered offspring of the expected midway birth weight at the normal gestation length.
Lower birth weights may result from higher environmental temperatures. Calves born in the northern U.S. have higher birth weights than in the South. The presumed cause is that the dam's altered blood flow to dissipate excess body heat takes some nutrients away from the placenta and fetus. This also results in reduced placental mass. If maternal environment is good, fetal body weight will be expressed at its genetic potential.
The dam's nutrition during gestation is an environmental factor that affects fetal birth weight. If necessary, the dam sacrifices body condition for the developing fetus. A fetus is capable of increasing the development of placental tissue during a dam's nutritional stress. In one study, thin cows, determined by BCS, had heavier placentas and normal-sized fetuses, and cows in normal condition had lighter placental weights and normal-sized fetuses. Fat mothers gave birth to normal weight calves, but pelvic fat deposits increased dystocia.. Calf losses in fat heifers were 45%, compared to 5% in those of ideal weight and 6% in poor condition. Fat heifers also had a high percentage of stillbirths due to slow delivery or malpresentation. A study on West African Dwarfs, published in 1991, showed higher death losses in both over- and underfed does.
Significantly low estrogen level is linked to dystocia (see the section below about normal parturition). A sire can confer to fetal genotype a depressing effect on maternal estrogen levels and thus increase dystocia rates.
Finally, cattle and sheep selected for increased muscling experience a steady rise in dystocia.
Maternal pelvic area is a significant factor in dystocia. Dairy cattle breeders have studied fetopelvic proportional dystocia and found big differences in dystocia and stillbirth rates between groups of related bulls who were the sires or maternal grandsires. Using information from these studies, they had a 60% reduction in dystocia and a 40% reduction in stillbirths. Using a sire's birth weight as the only criteria for calving ease is very misleading due to the fetal environment's large effect on birth weight.
Pelvic inadequacy may become obvious to owners or their veterinarians during delivery. Does with this problem should be eliminated from the breeding program. Young does that have not yet finished growing might be given another chance. Serious thought should be given to the potential breeding value of sons and kidding ability of daughters, as the dam is likely to pass poor pelvic size. Do not use sires whose daughters have poor pelvic capacity.
Some Pygmy does are not bred until they are 3 or 4 years old. The vast majority of older first kidders have problems with cervical dilation due to pelvic fat and "rusty" hormones. These does cannot be expected to deliver well.
Pelvic area heritability in cattle is high, at 50% to 60%, about twice as high as the 30% heritability of birth weight. Simultaneously selecting for both traits should give dramatic results. Pelvic area-to-birth weight ratio in cattle increases over several generations by selecting herd replacements wisely.
A complex chain of hormonal events initiates and sustains birth. Estrogen, prostaglandin, oxytocin and relaxin are the most important birth hormones. The hormone epinephrine can be a factor in delayed birth and dystocia.
Oxytocin receptors in the uterus develop in response to an increase in the estrogen-to-progesterone ratio in late gestation. Oxytocin, the hormone responsible for uterine contractions and milk let-down, is not effective without these receptors and unless calcium ions are also available. Prostaglandins liberate calcium ions. The number of oxytocin and estrogen receptors in the uterus vary, and females with an inadequate number experience sluggish progress in delivery. It is easy to see how keeping offspring from such can multiply this problem in a herd.
Epinephrine is released in response to any type of stress, and this inhibits the action of oxytocin. Stressors (confinement, moving to new surroundings, and unusual noises or activity) delay parturition due to the inhibition of oxytocin and increases dystocia. Allow the doe to deliver in familiar, non-threatening surroundings with a minimum of fuss.
The hormone relaxin is responsible for softening the ligaments and enhancing cervical dilation. Females producing insufficient amounts of these or other important hormones may pass this inadequacy to their offspring. Bucks out of mothers with these imbalances serve as gene transmitters to pass their dams' traits to their offspring.
Even using the wisest selection procedures for herd replacements and appropriate nutritional schemes for pregnant does, dystocia will be a factor in some deliveries. Timely assistance usually results in successful live birth. Unassisted first-calf heifers take almost twice as much time to deliver as experienced cows because their soft tissues - cervix, birth canal and vulva - expand more slowly. The rule of thumb for assistance is to intervene 30 minutes after the fetal membranes appear at the vulva. Pygmy goat breeders should follow this timetable, unless it is obvious that a kid is on the way and the birth is normal. (See Solving the Mysteries of Obstetrics.)
Effects of Dystocia on Newborns
Severe acid-base imbalances occur in the fetus during dystocia. Hypoxia (oxygen deprivation) and other factors can cause fetal death during dystocia, and it is a serious element in survivability due to respiratory distress and other factors. Contractions and pelvic pressure create fetal hypoxia and acidosis that can be minimized with early assistance. Newborns from prolonged dystocia are weak, often incapable of standing to nurse and/or lacking the suckle reflex, and they are much less able to absorb passive colostral antibodies from either the dam or artificial feeding. Fetal oxygen deprivation is sometimes the result of prolonged breech birth due to pinching of the umbilicus. Oxygen deprivation can also be the result of lung immaturity which is sometimes due to genetic factors.
Necropsied dystocial fetuses have one or more of the following: head/neck swelling, hemorrhagic lungs, lungs with fluid containing meconium aspirated in utero, ruptured diaphragm, ruptured liver, and fractures of legs, jaw, vertebrae, ribs, sternum or back. Hemorrhage and congestion of the meninges (brain membranes) is consistently found.
Viral and bacterial infections can be acquired through the navel stump and lungs at or shortly after birth, especially in dirty barns and kidding areas. Depending on the organism and/or strain, vaccination may help reduce these losses. Vaccines and antibiotics are not substitutes for good sanitation. Dipping the navel stump with 7% iodine as soon as possible after birth helps to avoid bacterial infections.
Three factors impact the regulation of body temperature in newborns: 1) large surface-area-to-body-mass ratio, 2) evaporation of fluids from the body and respiratory tract, and 3) low resistance to cooling. Kids that are born unassisted and breathe immediately do not normally chill unless weather conditions are particularly bad. Dystocia severely challenges newborns in bad weather.
On the day of birth, calf mortality increases progressively as air temperature decreases or as precipitation increases. Cold weather quickly depletes the neonate's energy reserves and results in progressive weakness or death. When they cannot generate sufficient heat from brown body fat and colostrum, newborns become hypothermic (below normal body temperature). An artificial heat source is needed to restore normal body temperature. To supply external heat, 1) lay the kid on a heating pad (medium heat) and cover with towels to retain the heat, 2) lay the kid on plastic milk jugs filled with 105o F water and cover with towels, or 3) immerse in 105o F water with the head held above water. You may put the kid inside a plastic bag to avoid getting it completely wet again, but do not include the head in the bag. As the water cools it lowers the kid's body heat, so the water jugs or bath should not fall below 102o F.
Cattle originating from Africa are less cold tolerant than European breeds, probably due to differences in skin thickness, hair coat length, hair texture and proportionately more skin surface area relative to body mass, all of which aid heat dissipation in the tropics. Cows of tropical origin bear lighter weight calves due to a smaller uterus, and their calves are more prone to chilling. Additionally, chemical interactions between Brahman dams and fetuses restrict the amount of fetal brown fat and leave calves less able to maintain body temperature. (Could Pygmies be similar, due to their tropical origin?)
Heat loss in dystocic newborns is greater due to depressed thyroid concentrations, elevated acidosis and reduced brown fat utilization due to oxygen deprivation. Dystocia reduces physical activity, teat-seeking behavior and appetite. Antibody absorption is also delayed. It is very important for newborns, especially those compromised by dystocia, to consume adequate colostrum soon after birth when heat loss rates are greatest.
Develop procedures to prevent hypothermia and act quickly to save kids. These include a clean, dry, protected birth environment; towel-drying the newborn; supplementary heat if needed; colostrum feeding; glucose administration (oral, sub-q or IP), and fluid therapy to treat acidosis in extreme cases.
Hyperthermia, or overheating, may occur in very warm weather. Panting and a rectal temperature above 103o F are the signs. Dehydration can be a secondary factor in hot, dry weather. The newborn can be laid on a bed of milk jugs filled with 101o F. water.
Immunization and Colostrum
Kids are born without antibodies to protect them from infectious diseases like tetanus, septicemia diarrhea, respiratory disease and navel or joint ill. If you have specific disease problems in newborns, there may be vaccines available to prevent them or antibiotic therapy to treat them. Immunize mothers before kidding to impart antibodies to neonates through colostrum. Work with your veterinarian to diagnose disease problems.
Remember, compromised neonates absorb antibodies poorly. Colostral antibodies are only absorbed through the kid's intestines for up to 24 hours after birth. Absorption is great for only a few hours and wanes rapidly until the 24-hour limit is reached, after which antibody absorption cannot occur. Passive antibodies protect the kid until 4-6 weeks of age, at which time its immune system starts to function. Then, its own vaccinations for active immunity become very important.
Antibody concentrations are 5-10 times higher in colostrum than in the dam's blood serum. There is a measurable decrease in the dam's serum antibody level, due to its concentration in the colostrum, in the period just before birth. The amount of colostrum present in the udder, and its antibody concentrations, vary by breed and parity number. First-milking colostrum is highest in antibodies.
When the dam has not been vaccinated to make passive colostral antibodies, kids should be vaccinated at birth. Tetanus antitoxin is extremely important and provides emergency antibodies for about two weeks.
Dystocic newborns have reduced activity and suckling ability. Since they absorb colostral antibodies inefficiently, they should be bottle fed if they can suckle or tube fed if they cannot. Tube feeding may place colostrum in the rumen which delays or prevents antibody absorption. Bottle feeding is preferred, if the kid is strong enough to suckle. Colostrum feeding should be 15% of the kid's body weight for the first 24 hours, divided into six equal feedings.
Besides dystocia, other factors may influence colostrum availability or ingestion include: poor udder and teat conformation, large teats, insufficient colostrum or milk production, premilking and poor mothering behavior. Maternal rearing ability is 10% to 20% heritable. Repeated poor maternal ability is a trait to cull.
Do not overlook the efficacy of the vaccination program if early deaths are a problem. Review your entire vaccination protocol, and possibly selenium supplementation, with your veterinarian.
Environment and Management
Most neonatal mortality is due to poor management, but genetics may also play a part. Producers may gain insight into environmental and management factors that cause individual and herd problems by consulting a veterinarian for a problem-solving visit. A veterinarian can assess your facilities, management strategies, skills, and the herd's nutritional status (BCS) to help determine the most likely causes of your problems and suggest solutions to overcome them. S/he should be able to recognize deficient pelvic capacity if s/he has attended your dystocias. Necropsies may also be valuable.
The goal in well-managed herds is to have over 90% of the young alive from birth to one month of age. Count every kid born. From that total, subtract aborted fetuses, stillbirths and kids that die up to one month of age. Then figure the percentage you have lost.
Death loss records are very helpful if you use the information to help diagnose causes and patterns in your herd. Accurate records show the truth. What you learn from them can be used to change environmental and/or management factors that contribute to death loss. You hurt yourself, your goats, your breeding program and your buyers with inaccurate or nonexistent records.
Buyers, ask questions about reproductive traits of potential purchases! The answers you get about kidding ease, birth weights, genetic defects, freedom from contagious and life-threatening diseases, and many other pertinent factors about the seller's herd will allow you to establish and maintain a more trouble-free herd.
A university veterinarian recently commented that 86% of the death loss in his state was due to the effects of dystocia. He said, "The non-infectious nature of these losses suggests that management, feeding, environmental protection and ventilation are all critical components of the equation. We can't win this battle with syringes and needles."
You are responsible for your herd management, your breeding program and the number of kids you lose to dystocia. Learn the skills to do better and cull animals with poor reproductive capacity.
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