Ram Singh Bibyan, Pramod Kumar, Somesh Rameshrao Gaikwad, Shweta, Jannat Saini, Priyanka Patir and Prajakta Kailas Sangale
Animal Nutrition Division
ICAR- National Dairy Resaerch Inatitute
Karnal-132001 (Haryana) India
Reproductive performance is a very important economic trait in dairy buffalo. Reproductive inefficiency results in increased calving intervals, increased involuntary culling rates, decreased milk production, and delayed genetic progress, among other problems, causing significant economic losses. Optimizing reproductive efficiency depends upon the successful completion of the following events: (1) a heifer must reach puberty before the start of the breeding season. Replacement heifers, as unproductive animals, should be considered as a cost. Thus the quicker the age at first calving, the quicker the return on investment. (2) must conceive early in the breeding season. (3) must calve unassisted. (4) the calf must survive to the time it is marketed, and (5) the heifer/cow must conceive in time to calve early during the subsequent calving season. Nutrition plays a pivotal role in maintaining the body condition and reproductive efficiency of dairy animals. Nutrient either in deficient or in excess amount has been shown to be capable of altering reproductive efficiency. One possible strategy that could be employed to improve reproductive efficiency within the dairy industries is nutritional manipulation. Therefore, improved reproductive efficiency should be a management focus as it is the main driver for commercial dairy husbandry.
Energy: The most important nutritional factor affecting reproduction in dairy buffalo is the energy intake. Energy status is a primary driver of optimum reproductive performance. If animal is in a negative energy balance, their chances of reproductive success are low. Inadequate energy intake in heifers will lead to delay in sexual maturity. Negative energy balance (NEB) is a common feature in high yielders during early lactation because of inadequate intake of energy due to reduced feed intake and mobilization of body fat reserves to meet its energy demand for high levels of milk production. Indeed, supplementation to improve or maintain energy balance is undoubtedly critical for optimum reproductive performance. Energy stores in body tissues are mobilized and weight losses occur, resulting delayed oestrus and conception. The mobilisation of body fat due to low levels of blood glucose causes increased blood levels of non-esterified fatty acids (NEFA) and ketone bodies like acetoacetate, acetone and b-hydroxybutyrate (BHBA). At the same time, blood levels of growth hormone (GH) are increased and that of insulin and IGF-1 are decreased. These metabolic changes are negatively associated with fertility. They include disturbances in LH pulse frequency, growth rate and diameter of the dominant follicle, weight of the corpus luteum, and progesterone and oestradiol concentrations. Increased NEFA concentrations in blood have been linked to greater incidences of ketosis, displaced abomasum, retained placenta and altered blood metabolites and hormone profiles. Proper feeding management can help to prevent the animal from NEB, resulting in improvement the production and reproduction of the animals. Fatty acids and cholesterol act as the substrates for reproductive hormone synthesis. Increasing fat in the diet may increase levels of reproductive hormones. Potential improvements in fertility with supplemental fat have generally been associated with increased dominant follicle diameter, improved oocyte and embryo quality. The level of total dietary fat in ration should not exceed 6-7% of diet. Mixture of cereal grain and forages usually contain about 3% fat, so up to 3 or 4% of dietary DM may come from supplemented fat. A number of studies have revealed that dietary supplementation of bypass fat in crossbred cows and Murrah buffaloes improved the milk yield and fat content. In buffaloes, about 100-150 g bypass fat per day could be supplemented to increase milk production performance. Supplementation of bypass fat at 2.5% of DMI resulted in increased birth weight of the calves, while time taken for expulsion of foetal membranes, involution of uterus, onset of cyclicity, the service period and number of inseminations per conception were reduced (P<0.05) in supplemented group. Increase in milk fat and yield was also reported in buffalo while supplementation of 15g bypass fat per kg milk yield, however, there was no effect on cyclicity and pregnancy rate.
Protein: Protein is vital to the maintenance, reproduction, growth, and lactation of animals. Low level of dietary protein severally affect rumen microbial growth and fermentation resulting in increased retention time of nutrients, decreased capacity to digest organic matter and depressed feed intake which affect animal performance. Holstein cows fed a 23.1% CP diet exhibited a 22% lower pregnancy rate when compared to the other group fed a 17.7% CP diet. When fed in excess, protein is utilized as source of energy especially in cases of energy shortage, since deposition of protein in reserve tissues of ruminants is limited to the extent of 8-22% of total body protein. Inefficiencies arise from elimination of surplus urea, which in turn increases energy requirement and may affect health and reproduction of the animals. Rumen microbial activity for efficient forage utilization is hampered when diet contains less than 7% CP. However, reproductive efficiency may be impaired if a protein is fed in excess amount of the requirement. Negative association between high dietary CP and fertility parameters was reported. Excessive feeding of protein during the breeding season and early gestation, particularly when the rumen receives an inadequate supply of energy, may be associated with reduced fertility. This decrease in fertility may result from decreased uterine pH during the luteal phase of the oestrous cycle in animal fed high levels of degradable protein. Animals fed 10-15% excess protein above the requirement involve more services per conception and had longer calving intervals. Supplementation of 15-19% excess CP resulted in lowered conception rate from 65 to 53%. The negative effects of protein supplementation are associated with an increase in blood urea-N, which affects ovarian follicular and embryo development. Successful embryo development depends upon the nature of the uterine environment, while increased urea level can decrease the uterine pH that would negatively affect the implantation and development of embryos, mostly at the cleavage and blastocyst formation stage. Higher serum urea levels because of excessive CP intake and poor body condition due to lower energy intake were the key factors for inferior reproductive efficiency in Nili-Ravi buffaloes.
Ca deficiency is common during parturition or within few days following parturition. The Ca:P ratio imbalance may affect ovarian function resulting in prolongation of first oestrus and ovulation, delayed uterine involution, increased incidence of dystocia, retained placenta and prolapse of uterus. Low Ca level in blood is associated with anoestrus and excess of Ca may affect reproductive health of animal by impairing absorption of P, Mn, Zn, Cu and other elements. Ca:P ratio between 1.5:1 and 2.5:1 for lactating animal should be maintained. Dry animals should be provided with optimum levels of Ca and P to decrease the incidence of milk fever which is important for maximizing reproductive efficiency. Ca present in the seminal plasma of buffalo bulls plays an important role in preserving spermatozoa motility and viability, as well as antioxidant status by protecting the sperm cells oxidative damage. P deficiency is associated with reduced production performance, abnormal sexual behaviour resulting in decreased fertility rate, feed intake, milk production, decreased ovarian activity, delayed sexual maturity and low conception rates in dairy animals. Delayed attainment of puberty, silent or irregular estrus in heifers, failure of estrus, long inter-calving period, still birth or weak calves or even embryonic death due to lack of uterine muscle tone are reported to be some of important clinical manifestations by the animals on P deficient diet and the excess of P renders the endometrium susceptible for infection. P is also needed for the maintenance of glycolysis and motility. The P concentration detected in the seminal plasma of bulls was positively correlated with quantity and quality parameters of semen. Na and K are responsible for maintaining osmolarity and activity of spermatozoa and regulate sperm motility and the acrosome reaction. Mg is required for capacitation, hyperactivation and acrosome reaction of spermatozoa in male reproduction. Mg level in the seminal plasma increases with sperm concentration but has no significant bearing on sperm motility, however, positive effects of Mg on the motility, morphology and concentration of spermatozoa were reported. Mg content in the seminal plasma was positively associated with the total antioxidant status of semen. Sulphur containing compounds increased the mobility and survivability of the cryopreserved spermatozoa.
Micro minerals: Mn deficiency results in delayed estrus, reduced conception rate and deformed calves. Cu deficiency in ruminants is associated with delayed or depressed estrus, long post-partum return to estrus period; anoestrus, silent heat, abortion and fetal resorption. Cu rich diets enhance spermatozoa motility and it may also act on the pituitary receptors which control the release of luteinizing hormones (LH). Cu deficient or excess levels may affect spermatocytogenesis with regard to sperm production, maturation and fertilizing capacity. Excess feeding of Mo resulted in decreased libido, reduced spermatogenesis and sterility in males and delayed puberty, reduced conception rate and anoestrus in females. Cobalt deficiency causes reduced fertility and increased early calf mortality. Depletion of cobalt at parturition results in decreased milk production. Semen contains a certain amount of Fe, required for a normal spermatozoa production and functions. The total Fe content of the buffalo seminal plasma was highly associated with sperm motility and viability. Fe content within the seminal plasma is important for the preservation of sperm motility and viability after ejaculation, and its presence will help spermatozoa to maintain their functions. Increased Fe concentration can affect negatively the morphology and DNA integrity of spermatozoa. Zn is essential for sexual maturity and early attainment of puberty. Seminal Zn has an important role in the physiologic functions of the sperm cell and that its reduced levels result in low seminal quality and subsequent chances of fertilization. Severity of udder edema increased when heifers were fed NaCI (23 or 136 g/d) or KHCO3 (0 or 272 g/d) in the diet but not when both salts were added together. Alteration of dietary cation-anion difference by addition of Cl may effectively reduce incidence and severity of parturient hypocalcaemia.
Vitamins: Vitamins C, D, E and B-complex are either synthesized by rumen microorganisms, by the animal body or available in most common feedstuffs. Vitamin A, is deficient in mature forages, crop residues, and other poor quality forages. The deficiency of which definitely plays an important role in embryonic development and its supplementation before and after calving may increase conception rate. Vitamin A deficiency in dairy animal result in delayed sexual maturity, abortion, birth of dead or weak calves, retained placenta and metritis. Dairy animals and heifers consuming diets deficient in β-carotene suffered delayed uterine involution, first estrus after calving, or ovulation and increased incidence of cystic ovaries. Buffalo requires vitamin A or its precursor β-carotene in its diet. Daily feeding of 2-3 kg green generally meets the requirement of vitamin A. When no green fodder is available, lactating buffalo should be supplemented with vitamin A (20000 to 45000 IU/d) and growing buffalo should be fed 2000 to 8000 IU/d. Vitamin E supplementation at 1,000 IU from 30 to 60 days postpartum decreased postpartum estrus interval, days open and services per conception suggesting that the supplemental dose might be reduced from 1,500 IU to 1,000 IU from 30-60 days postpartum in buffaloes. Generally, there is no need for supplementing other vitamins to adult buffalo.
Nutrition associated disorders affecting reproductive efficiency of animals:
Ketosis and fatty liver: Fatty liver and ketosis is a common metabolic disease of lactating animals occurring during the first 10-60 days post-calving. The three-week period after calving seems to be the most critical time of lactating animals and disease occurs during periods when blood non-esterified fatty acid (NEFA) concentrations are elevated. Liver uptake of NEFA is proportional to blood concentration. NEFA can be esterified or oxidized in liver mitochondria or peroxisomes and the product is triglyceride. In ruminants, export of triglyceride from the liver, as part of very low density lipoproteins, occurs at a very slow rate compared to other species. Incomplete oxidation of NEFA leads to formation of ketones: acetoacetate and beta-hydroxybutyrate. Ketonemia is common at calving during the sudden surge of NEFA, when energy requirement for milk production far exceeds the energy intake, and as a secondary disorder that may cause depression in feed intake and elevated NEFA. Many reproductive disorders like delayed involution of uterus, retention of placenta, onset of estrus are associated with elevation of NEFA and ketone bodies.
Milk fever: Milk fever is mainly a problem of older, third to sixth lactation, high-producing dairy animals. It is associated with parturition, usually within 72 h of giving birth. Almost all animals experience some decrease in blood calcium (hypocalcaemia) during the first day postpartum. Animals fed diets that are relatively high in K or Na is in a relative state of metabolic alkalosis which increases the risk for occurrence of milk fever. Adding anions reduced metabolic alkalosis and induced mild metabolic acidosis. Chloride salts are more acidogenic than sulfate salts. Feeding of Mg (0.35-0.40%) in prepartal rations prevents a decline in blood Mg level at parturition. P requirement are met by feeding 40-50 g per animal per day. Feeding of less than 25g of P per day may lead to a downer cow syndrome. More than 80g may induce milk fever. The optimal prepartal dietary Ca concentration is not well defined but very high Ca (>100g) may reduce feed intake and animal performance.
Udder Oedema: Udder oedema is a peri-parturient disorder characterized by excessive accumulation of fluids in the intercellular tissue spaces of the mammary gland. Incidence and severity are greater in pregnant heifers than in adults, and tend to be more severe in older than in young heifers. Excessive intakes of Na and K were implicated as causative agents in udder oedema. K fertilization to increase forage production could be the cause of increased udder oedema. The reduction of udder oedema by CaCl2 was most prominent during the first week of feeding. Oxidative stress of mammary tissue resulting in reactive oxygen metabolites may play a role in udder oedema. A diet must supply adequate vitamin E; Cu, Mg, Zn, Mn and Se to reduce the risk of udder oedema.
Retained placenta (RP) and metritis: RP is a failure of the fetal membranes to be expelled within 12 to 24 h after parturition. Metritis, an inflammation or infection of the uterus, is often associated with RP. Multiple physiologic and nutritional factors have been associated with causes of RP and metritis. Nutritional factors of RP are primarily due to the diet fed 6-8 weeks before calving. Extreme deficiency of dietary energy, protein or both can result in RP. Animals fed diets low in dietary CP (50%) of RP compared with cows fed 15% CP (20% incidence). Fat cow syndrome is also frequently associated with increased incidence of RP and metritis. The rate of RP is associated with imbalances in Ca and P metabolism.
Feeding strategies to improve reproductive efficiency of buffaloes:
Feeding of buffalo heifers: Calves from 6 months of age to adult can be reared on roughage based diet with minimum amount of concentrates. Ration containing 12% CP and 60% TDN (10 kg green fodder, ad lib straw and standard concentrate mixture containing 20% CP and 70% TDN (maize, 30 kg; GNC, 30 kg; wheat bran, 38 kg; mineral mix, 2 kg; salt, 1 kg per 100 kg) @ 1.5, 2.0, 2.5 and 3.0 kg per day for 100, 150, 200, 250 kg BW will provide an average daily growth of 500g. Scientific feeding is required for optimum growth, as buffalo heifers attain puberty when threshold body weight is about 60% of mature weight. With proper feeding, buffalo heifers attain puberty at the age of 17-21 months with a body weight of 270-300 kg. However, very high plane of energy nutrition inhibits development of milk secretary tissue in mammary gland, which reduces lifetime milk production ability.
Feeding of pregnant buffalo: Buffaloes should be fed to support 750-900g average daily weight gain during last 2 month of pregnancy and about 700g average daily weight gain during the last 3 month of pregnancy. In pregnancy of adult buffalo, CP requirement increases by 3, 8.4, 16, 26, 43 and 64% of maintenance requirement on 5th, 6th, 7th, 8th, 9th and 10th month of pregnancy, respectively. The corresponding increases in TDN requirements are 4.3, 7.2, 18.8, 22.2, 39.0 and 67.4% of maintenance requirement, respectively. Pregnant buffaloes should be dried at least 2 month before expected date of calving
Feeding of lactating buffalo: Dietary energy is the most limiting factor in milk production. Lactating buffalo should be fed sufficient nutrients for their milk production and maintenance. Milk production increases gradually, reaches peak at 42- 56 days after calving, and the peak is maintained for next 70 days. It declines gradually thereafter from 126 to 305 days. Inadequate energy intake in early lactation leads to loss of body weight and delay in initiation of post calving oestrous cycle. By and large, ovarian cycle ceases when buffalo looses 15 to 24% of BW. Thus, utmost care should be taken so that they are not underfed during early part of their lactation. The lactating buffaloes in their first and second lactation continue to grow and thus additional 20 and 10% of maintenance requirement should also be provided in first and second lactation, respectively. For a buffalo of 450 kg producing 10 kg milk; 5.0 kg concentrate mixture, 7 kg straw and 20 kg legume fodder/40 kg cereal fodder per day should be fed depending on the availability. For every 50 kg increase or decrease in BW, 350g grain+ 1 kg straw+ 3 kg berseem + 2.5 kg cereal fodder has to be added or reduced, accordingly.
Feeding of breeding buffalo bulls: Breeding bulls should be fed good quality balanced ration for proper development of testicular tissue and improved semen quality. They should attain about 400 kg BW at 30 months of age. They should also be fed good plane of nutrition as low protein diet could delay puberty by 5-6 months with poor testicular development and small semen volume. Maintenance level feeding of bulls without energy allowance resulted in reduction in sperm numbers by 32 and 41% as compared to those receiving twice and thrice maintenance requirements. Therefore, breeding bulls should be fed 100% higher CP and 20% higher energy than maintenance requirement of mature female buffaloes.
Buffalo remains underfed due to poor availability of nutrients particularly protein as tropical forages get lignified. Under nutrition results in the loss of body weight and body condition, delays the onset of puberty, increases the post-partum interval to conception, interferes with normal ovarian cyclicity by decreasing gonadotropin secretion and increases infertility. The major reproductive factors in buffalo husbandry which contribute to low income of the farmers are delayed puberty, long calving intervals, short productive life and high calf mortality. The level of the excess, deficiency or imbalance of nutrients affecting reproduction is not very lucid. Optimum feeding as per requirements of energy, protein, vitamins and minerals is pre-requisite for achieving optimum reproductive efficiency in buffaloes. Improving reproductive efficiency in dairy animals is essential to continually improve milk production to meet the growing global demand for animal food products. In dairy operations, the goal is to produce one healthy calf per cow per year. Therefore, the nutritional factors influencing reproductive efficiency are an area of research for increasing life time productive performance of dairy animals.