Topic:Lactation
Lactation in horses refers to the process by which mares produce milk to nourish their foals following birth. This physiological process involves the mammary glands, which undergo significant changes during pregnancy and after foaling to produce and secrete milk. The composition of equine milk includes essential nutrients, antibodies, and bioactive components that support the growth and immune function of the foal. The lactation period in horses typically lasts for several months, during which the mare's nutritional and health status can impact milk production and quality. This page compiles peer-reviewed research studies and scholarly articles that explore the biology, management, and nutritional aspects of lactation in horses, as well as its implications for foal development and mare health.
Diurnal changes in lactic and pyruvic acid levels and pH values in foals during the first 13 weeks of their life and in their lactating mothers. 1. The diurnal changes in the levels of lactic (LA) and pyruvic (PA) acids and values of pH were studied in standard-bred mares and their foals, for 13 weeks of foal life, throughout 2 years. 2. The studies began when a foal was 7 days old and were repeated every 2 weeks until foals reached 13 weeks of age. 3. Blood samples were taken every 4 hr for one day, each second week. 4. In the LA, PA levels and pH values no diurnal rhythm was stated in lactating mares during study periods. 5. In foals the diurnal rhythm in LA and PA occurred in the 3rd month of their life, with the acrophase at night ...
The effects of copper supplementation on the prevalence of cartilage lesions in foals. The potential role of dietary copper in the development of cartilage defects in foals was investigated. Twenty-one mares were fed rations containing 13 ppm copper (CuC, control) or 32 ppm copper (CuS, supplemented) during the last three to six months of gestation and first three months of lactation. Their foals were fed pelleted concentrate containing 15 or 55 ppm Cu and were destroyed at 90 (5 CuC and 5 CuS foals) or 180 (6 CuC and 5 CuS foals) days. Focal cartilage lesions were found at multiple sites on necropsy. In foals killed at 90 days, there were over twice (9 versus 4) as many lesions...
Yield and composition of milk from lactating mares: effect of lactation stage and individual differences. The yields and composition of milk from nursing mares were studied during the first two months of lactation in 11 mares of heavy breeds (784 kg). Daily yield increased from 21.7 to 24.6 kg between weeks 1 and 8 of lactation. Fat, protein, gross energy and Ca concentrations significantly decreased when lactose content increased during this period. Individual variations were higher for yield than for composition. Casein, whey protein and non-protein N (56, 34 and 10% of crude protein, respectively) and amino acid composition did not vary between weeks 1 and 8 of lactation.
A conceptual approach to optimal nutrition of brood mares. Cumulative nutritional demands on good brood mares are unrivalled among domestic livestock, but little attention has been given to the influence of nutrition on their reproductive performance and efficiency. We suggest that part of the decline in racing performance of progeny of mares over 10 years of age may be caused by suboptimal nutrition. This article contrasts the concepts of minimal and optimal nutrient requirements, revives Hammond's concept of nutrient partitioning to the conceptus and mammary gland, and discusses energy and nutrient requirements during gestation and lactation. Furthe...
Diurnal changes in the haemoglobin level, red blood cell number and mean corpuscular haemoglobin in foals during the first 13 weeks of life and in their lactating mothers. 1. In six foals and their mothers (of Standard breed) diurnal changes in the haemoglobin level, red blood cell number and mean corpuscular haemoglobin during the first 13 weeks of foal life were studied. 2. Studies begun when a foal reached 7 days of age and were repeated every two weeks till 13 weeks of foal life. Blood was taken every 6 hr in foals and every 4 hr in mares. 3. No diurnal rhythmicity in parameters studied either in foals or in mares was found. 4. Decrease of haemoglobin level in lactating mares (14.0-12.5 g/100 ml) without changes in red blood cell number were observed. Mean c...
Relationships of total protein, specific gravity, viscosity, refractive index and latex agglutination to immunoglobulin G concentration in mare colostrum. A colostrum sample was collected within 24 h after foaling from 27 mares and from 10 other mares a milk sample was collected several weeks post partum. Immunoglobulin G concentrations were determined quantitatively by radial immunodiffusion and semi-quantitatively using a commercial latex agglutination test. Total protein, specific gravity, viscosity and refractive index were determined and their relationships to the immunoglobulin G concentration analysed. All parameters correlated with the immunoglobulin G concentration. The latex agglutination test divided the colostrum samples into three g...
Histochemical and biochemical observations on milk-fat-globule membranes from several mammalian species. A specific secretory product of the lactating mammary gland are triglyceride fat globules which are enveloped by a very complex membrane, the milk fat globule membrane (MFGM). In different mammalian species (man, rhesus monkey, horse, goat, sheep, cow, grey seal, camel, alpaka) the glycoproteins of this membrane have been analyzed by gel electrophoresis, Western blotting and lectin histochemistry. A remarkable intra- and interspecific variability of these glycoproteins has been detected pointing to so far unknown physiological adaptions, which may play a role in the intestine of the new born. ...
Absorption of two trimethoprim/sulphonamide combinations from the uterus of pony mares. Plasma drug concentrations were measured after two commercially available potentiated sulphonamides, trimethoprim and sulfadoxine and trimethoprim and sulphadiazine, were infused daily for 2 and 3 days, respectively, into the uteri of pony mares which had been mated before ovulation. Intravenous administration of trimethoprim and sulfadoxine allowed uterine absorption of trimethoprim (23-43%) and sulfadoxine (29-34%) to be calculated. After intra-uterine administration trimethoprim and sulphadiazine were detected in the milk of a lactating mare. In order to maintain plasma concentrations likel...
Reproductive traits, lactation and foal growth in mares fed altrenogest. Lactating mares were assigned as controls or fed altrenogest (.044 mg.kg body wt-1.d-1) for 15 d after foaling. Mares (n = 6) fed altrenogest were inseminated during the first estrus after treatment and mares (n = 6) in the control group were inseminated during the second postpartum estrus. Ovulation during the estrus in which mares were inseminated occurred 26 +/- 1 d postpartum for treated mares and 36 +/- 1 d postpartum for control mares. The percentage of mares conceiving was not different for control (67%) and alternogest-treated (100%) mares. No differences were observed in tone and size...
Differences between individuals in high-molecular weight glycoproteins from mammary epithelia of several species. Milk fat globules are secreted by envelopment in plasma membrane of the lactating cell. SDS-gel electrophoresis of proteins from this membrane has revealed differences between milk donors in two mucin-like glycoproteins. One of these glycoproteins resolves in 3% acrylamide stacking gel and the other in 4% running gel. The proteins vary in number of bands (one or two) and band mobilities. This polymorphism arises, at least in part, from expression of hypervariable genes. In this study, gel electrophoretic evidence of similar polymorphism in glycoproteins from cow, chimpanzee, horse and human mi...
Comparison of the lipoprotein pattern of the horse, the pony and the lactating and non-lactating cow obtained by a combination of an ultracentrifugation and a precipitation technique. 1. The serum lipoprotein pattern was studied in four horses, four ponies and in three high producing lactating and three non-lactating cows. The lipoprotein pattern was estimated with a combination of the preparative ultracentrifugation and the heparin-manganese precipitation technique. 2. The lipid composition of the lipoproteins of horse, pony, lactating cow and non-lactating cow was determined. 3. In all three species more than 50% of serum total lipids was found in the HDL fraction. 4. The mean chylomicron fraction in horse and pony was 3.1%. In the cow it varied from 1.5 to 2.5%. 5. Betwe...
A study of diurnal changes in cortisol and glucose levels and FDPA activity in foals during the first 13 weeks of life and in their lactating mothers. 1. In six standard-bred mares and their foals diurnal changes in the cortisol and glucose levels and in FDPA activity were studies for 13 weeks of foal life. 2. In the cortisol level diurnal rhythm was found in the 3rd, 7th and 11th week of foal life and in the 11th week of lactation in mares. 3. In mares the mean diurnal cortisol level changed from 32 ng/ml in the first week to 57 in the 11th week and in foals from 24 in the first week to 16 ng/ml in the 11th week. 4. In the glucose level no diurnal rhythm was observed. 5. In mares the mean diurnal glucose level after parturition was about 58...
Characteristics of milk ejection, associated intramammary pressure changes and oxytocin release in the mare. The neuroendocrine reflex theory of milk ejection was investigated in the horse under natural suckling conditions. To this end 12 lactating mares were provided with acute jugular catheters and with intramammary pressure (IMP) recording catheters. The foal had free access to the contralateral mammary complex. Intramammary pressure could thus be recorded while blood was drawn simultaneously for oxytocin analysis from the undisturbed animal. Suckling periods associated with a characteristic increase in IMP lasted significantly longer than unsuccessful nursing attempts. Elements of successful suck...
Interspecies variation in milk composition among horses, zebras and asses (Perissodactyla: Equidae). Milk samples of four species of wild equids (onager, Equus hemionus onager; mountain zebra, E. zebra hartmannae; plains zebra, E. burchelli; Przewalski horse, E. caballus przewalskii) and two domesticated equids (ass, E. asinus; pony, E. caballus) were analysed. At mid to late lactation the milks of all species were very similar, containing on average 10-12% total solids, 1-2% fat, 1.6-1.8% true protein, 6-7% 'lactose', 0.3-0.5% ash, 0.08-0.12% calcium, 0.04-0.07% phosphorus and a calculated energy content of 2.0-2.4 kJ/g. Milk samples collected in the first 2 weeks after birth showed elevated...
[The problems of mastitis in mares]. Based on a group of 33 mares infected with mastitis, data regarding the time of appearance, the clinical symptoms and the bacteriological causes of the disease were evaluated. The cases were distributed as follows: 27.3% before delivery, 24.2% immediately after delivery (until the third day), 12.1% during the middle and late stages of lactation, 9.1% immediately after the weaning of the foal and 27.3% outside the lactation period of non-pregnant mares. The clinical picture is described. In the majority of the cases, both halves of the udder were infected. The analysis of the bacteriological re...
Complications associated with Streptococcus equi infection on a horse farm. Complications associated with Streptococcus equi infection developed in 15 (20.3%) of 74 horses on one farm included death, guttural pouch empyema, purpura hemorrhagica, upper respiratory tract obstruction, pneumonia, pleuropneumonia, agalactia, mesenteric lymph node abscessation, and periorbital abscessation. Death was attributed to pneumonia in 3 horses and to upper respiratory tract obstruction in 2 horses. One horse was euthanatized because of severe purpura hemorrhagica.
Establishment and maintenance of pregnancy after embryo transfer in ovariectomized mares treated with progesterone. Pregnancy was established and maintained after embryo transfer in 3 ovariectomized mares treated with progesterone only. Four ovariectomized mares were used as recipients, and 7 transfers were performed. Progesterone in oil, 300 mg i.m. daily, was given starting 5 days before transfer of a 7-day embryo. If the mare was pregnant at 20 days, progesterone treatment was continued to 100 days of gestation. The 3 pregnant mares carried to term and delivered live foals with normal parturition, lactation and maternal behaviour. No differences were seen between pregnant and non-pregnant ovariectomized ...
Atrial fibrillation in a pregnant mare: treatment with quinidine sulfate. Atrial fibrillation in a pregnant, lactating, 15-year-old mare nursing a 70-day-old foal was converted to normal sinus rhythm, using quinidine sulfate. The maximum concentration of quinidine was 4.3 mg/L in the mare's milk and was 2.6 mg/L in the mare's serum. Treatment with quinidine did not interrupt the pregnancy. Six months after treatment, the mare developed acute volvulus of the large colon and died. At necropsy, the mare did not have macroscopic or microscopic cardiac lesions. The fetus was macroscopically and histologically normal.
Identification and the primary structure of equine alpha-lactalbumin B and C (Equus caballus, Perissodactyla). The presence of two new alpha-lactalbumins has been demonstrated in the colostrum of a single mare (Equus caballus, Persian Arab). They have been designated equine alpha-lactalbumin B and C, and that isolated previously from the milk of Australian horses (English Thoroughbred) as alpha-lactalbumin A. The primary structures of B/C have been determined by automatic Edman degradation of enzymatic cleavage of the oxidized protein. Cyanogen bromide cleavage of S-carbamoyl-methylated protein provided necessary overlapping peptides. Comparison of the sequences of B and C with that of A indicates 3 an...
Prolactin response to thyrotrophin-releasing hormone stimulation in normal and agalactic mares. Serum prolactin concentration was determined before and after TRH administration to normal mares at 10 months of gestation, 2 and 4 months post partum and during a -7- to +14-day peri-parturient period. The serum prolactin concentration increased significantly (P less than 0.05) at 15, 30 and 60 min after TRH administration in the normal mares regardless of the season of the year, pregnancy or lactation status. However, during the periparturient period, the basal prolactin concentration was increased 4-fold and there was only a marginal increase after TRH administration. Of 9 agalactic mares, ...
Carnitine concentrations in the milk of different species and infant formulas. Carnitine concentrations were measured in the milk of sheep, cows, goats, and horses, in human milk of term and preterm infants and in European infant formulas. There were significant species' differences in carnitine milk content. Acylcarnitine concentrations ranged from 13 to 47% of total carnitine. This may be related to differences in maternal and/or mammary gland metabolism. The concentration of long-chain acylcarnitine in milk was under 1% in all investigated species. In cow's milk, there was a decrease in acylcarnitine concentration during the first 2 months of lactation. In human milk,...
Fatty acid composition of the plasma lipids of the maternal and newborn horse. The fatty acid composition of the plasma free fatty acid, triacylglycerol and phospholipid fractions was measured in blood and milk samples taken daily from 3 mares and their foals on Days 1-9 post partum inclusive, and from a total of 12 mares and foals on Days 22, 30 and 51. A rise in the plasma concentrations of triacylglycerol and phospholipid similar to that well documented in other species occurred in the neonatal period. Alterations in the composition of the foal plasma phospholipid after birth lend support to the view that the placenta rather than the fetus could be responsible for the...
Lactation in the horse: the mineral composition of mare milk. Changes in the mineral composition of mare milk during lactation were studied. Milk samples were obtained from five Thoroughbred mares one to three times weekly from the first to the eighth week of lactation and from two of the mares for an additional 8 wk. Samples averaging 500 mL were obtained after oxytocin was administered to the mares. Each sample was analyzed for total solids, ash, calcium, phosphorus, magnesium, sodium, potassium, copper and zinc. The concentration of all constituents except sodium and potassium decreased throughout lactation. The rates of decline of ash, calcium, phosp...
Passive transfer of mucosal antibody to Streptococcus equi in the foal. Passive transfer of mucosal antibody to Streptococcus equi was studied in foals during the first 2 months of life. Immunoglobulin G (IgG) and IgA antibodies were found in sera and nasal secretions of foals shortly after colostrum intake. Titers were highest 2 days after birth; IgG predominated in sera, and IgA predominated in nasal washes. Intragastrically administered 99mTc-labeled IgA was transported from the bloodstream to the nasal mucosa of a newborn foal within a few hours of colostrum intake. Western blot analysis of the specificities of colostral and serum antibodies showed that select...
Observations on the long term effects of Brucella abortus infection in the horse, including effects during pregnancy and lactation. Five mares and a stallion were studied from three to 30 months after experimental infection with Brucella abortus strain 544. The mares bred normally. No organisms were recovered from horses or from pregnant Friesian heifer contacts. Titres of serum antibody in the antiglobulin (Coombs) and complement fixation tests fell more slowly than those assessed by other tests. The serum of one foal yielded maternal antibody. An intradermal test was positive in infected adults only, and negative in all foals.
Plasma prolactin concentrations and cyclic activity in pony mares during parturition and early lactation. Five pony mares were blood sampled during late pregnancy, foaling and early lactation. An homologous assay for horse prolactin was used to measure plasma prolactin concentrations in these samples. Regular estimates of cyclic activity were also made. Plasma prolactin concentrations rose markedly in the last week of pregnancy and remained high although variable in early lactation, before declining to basal levels by 1-2 months post partum. All mares showed a post-partum oestrus 7.0 +/- 0.9 days after parturition. One mare whose foal died shortly after birth showed a rapid decline in plasma prola...
Composition of milk from pony mares fed various levels of digestible energy. Twenty-two pony mares were fed one of three diets that provided 93.0, 74.8 or 57.2 kcal of digestible energy (DE) per kg body weight per day. Milk samples were taken at 14 day intervals. A total of five samples were taken from each mare. The samples were analyzed for total solids, crude protein, lactose, total lipids, ash, calcium and phosphorus. Gross energy was calculated from composition data. Increases in energy intake decreased the concentration of total solids, protein, fat and gross energy of mare's milk. Energy intake had a greater influence on the mare's body condition than on milk en...
A comparison of the mineral composition of milk of domestic and captive wild equids (Equus przewalski, E. zebra, E. burchelli, E. caballus, E. assinus). Milk samples were obtained in early and/or late lactation from Przewalski horses, Hartmann's zebras, Grant's zebras, domestic horses, ponies and a mule mare made pregnant by embryo transfer. Samples were compared for their content of total solids, ash, calcium, phosphorus, magnesium, sodium, potassium, copper, zinc and iron. Milk from the Przewalski horses, Hartmann's zebra and the domestic horse had similar mineral composition and the content of minerals was higher in early than in late lactation. Milk from the domestic mule contained the lowest concentration of calcium, phosphorus and zinc b...
Relationship between nutrient intake, growth and body composition of the nursing foal. The milk and nutrient intakes of 21 nursing foals of heavy breeds (adult weight: 800 kg) were determined at 1, 4 and 8 weeks of age. Lactose intake increased (P is less than 0.01) from 1 300 g/day at 1 week of age to 1 800 g/d at 8 weeks; fat decreased (P is less than 0.01) from 400 g/d to 300 g/d and protein did not vary (600 g/d). Energy and nitrogen intakes did not depend on the source of energy in the mother's diet. Milk, energy and nitrogen intakes were well related (r = 0.74 to 0.81) with foal growth between 1 and 4 weeks, but not between 4 and 8 weeks. The composition of weight gain sho...