Introduction
The mortality in newborn calves is a major economic loss on the dairy farms. It varies from 8% to 84% globally. The large variation in calf mortality is due to disparities in calf management practices. Although knowledge of scientific dairy management improved, lack of reproductive cyclicity, high calf morbidity and mortality, and high incidences of mastitis, lameness, and ketosis remain to be a challenge in dairy herd management. Often calves suffer from multiple disease incidences owing to poor hygiene, weather, infectious agents, overcrowding, mixing with the herd, and so on. The rearing and feeding management followed after calving, have a long-term influence on the calf growth and lifetime performance. The time of colostrum ingestion, calving difficulty, and calving season have a greater influence on calf morbidity and mortality among 21 potential risk factors reported [1]. The morbidity and mortality risk is higher in calves when the colostrum feeding is delayed by 6 hours, poor parturition conditions, and wet or cold seasons. The economically justifiable limit of calf mortality is between 2% and 5% beyond which it is intolerable.
Feeding colostrum soon after birth alone would not help to lessen the calf morbidity and mortality. The feeding colostrum soon after birth theoretically imparts immunologic protection only for 2–4 weeks. Improving the innate immune in the first month (mo) of the birth is necessary to reduce calf mortality. The newborn calf should receive 150–200 g of immunoglobulins (Ig) within 2 hours of birth to avoid the risk of diseases [2]. The morbidity and intensity of the disease course were lowest in calves when serum Ig exceeded 10 g/l at 30–60 hours after birth [3].
About 60% of calf mortality in the first month (mo) of life is due to neonatal calf diarrhea [4]. Many believe that the Bos indicus neonatal calves are resilient to calf diseases compared to crossbred calves but, the fact is that they too are fragile at birth [5]. Nutritional interventions during neonatal age are essential for developing innate immunity that occurs in small steps until 6 months besides milk feeding [6]. Various nutritional supplements such as adding antibiotics to milk, milk replacers, fats and oils, vitamins and minerals, etc., were made to boost the innate immunity in the calves. Research workers supplemented oils namely corn, cottonseed, and soybean in the milk replacer to improve the health of calves and inferred oils rich in oleic acid such as canola improved diarrhea [7]. The flax seed (Linumus itatissimum) oil (FSO), rich in omega-3 fatty acids, contains 60% linolenic acid and 8%, 16%, and 16% saturated, oleic, and linoleic fatty acids, respectively, has anti-inflammatory, antipyretic, analgesic, and antioxidant properties [8]. Hence, the present study was planned to improve calf resilience to diarrhea and other common diseases in neonatal calves by orally supplementing FSO.
Materials and Methods
Experimental location
The experiment was carried out at the Livestock Research Centre, ICAR-National Dairy Research Institute, Southern Region, Bangalore, India. The experimental place’s latitude, longitude, and elevation are 12.947014°N (12°56’49.2504’’N), 77.607679 (77°36’27.6444’’E), and 921m MSL, respectively. According to the Köppen-Geiger climate classification, the tropical climate of the location is considered Aw (Savanna, wet), with a mean temperature of 23.6°C and annual rainfall of 831 mm. The variation in temperatures throughout the year is ±6.4°C. During the experimental period, the relative humidity ranged from 59% to 72%.
Ethical clearance
The trials were conducted with the approval of the Institute Animal Ethics Committee (1904/GO/ReBi/L/16/CPCSEA/IAEC/SRS-ICAR-NDRI-2017/No.16) and reared as per the guidelines of the Committee for Control and Supervision of Experiments on Animals (CPCSEA), New Delhi, India.
Experimental calves
Tincture iodine was applied to the navel card region of all the claves soon after the birth and fed colostrum for 5 days at the rate of 10% of the body weight. Twenty Deoni (B. indicus) calves born in the fourth parity were isolated on day 6. Calves were randomly allocated into four groups based on birth weight and gender (males, 21.31 ± 0.46 kg, and females, 20.22 ± 0.80 kg).
Experimental groups and feeding schedule
A group of male and female calves was supplemented orally with 30 ml/day of FSO till 28 days of age every day at 8 AM and considered as treatment groups (TGs). Calves in TGs were compared with the control groups (CGs) of male and female calves without FSO supplementation. Calves were housed in separate cells as per the group and gender from day 6 to 90 of age. FSO supplementation in TG was stopped on day 28 and subsequently replaced with a bolus consisting of 25 g each of ground flax seed and jaggery until 90 days of age. During the period, dam milk yield (kg/day), let downtime (minute), milk flow rate (ml/strip), calf mean suckling time (no/minute), and suckling rate (no/minute) were recorded manually using a stop-clock and a cell counter. Milk was analyzed for total solids, milk protein, fat, and lactose [9].
During neonatal age, each calf was allowed to suckle the dam every day for 3 minutes at the beginning and end of the manual milking at 6 AM and 5 PM, respectively. Milk suckling during the preweaning period was restricted to 1 and 5 minutes before and after milking from day 29 to 90 after birth, respectively. All the calves were offered weighed quantities of fresh mixed green fodder (MGF) consisting of tender maize (Zea mays) fodder, para (Bracharia mutica), and guinea (Megathyruses maximus) grass in equal proportion and chaffed manually to 10 cm length. Calves in CG and TG during the preweaning period were also fed 200 g of concentrate mixture (CM) having 17% crude protein at 9 AM from day 29 to 90. Tender MGF was offered to calves at free choice from day 10 of birth. All calves were provided drinking water four times daily from 9 AM to 9 PM.
Fecal score, egg count, and blood analysis
Fecal consistency (FC) and physical appearance of calves during neonatal and preweaning age were measured by adapting standard protocol using a four-level scoring from zero to 3 [10]. Fecal egg count (FEC) was carried out by taking 3 g of rectal fecal sample in a 100 ml plastic bottle and mixing thoroughly after adding 42 ml of tap water. The homogenized suspension was filtered through a sieve. The filtrate was collected, agitated, and filled into a test tube of 15 ml capacity and centrifuged at 2,000 rpm for 2 minutes. The supernatant was discarded, and the sediment was agitated filled the tube with floatation solution to the previous level, and mixed thoroughly. The fluid was removed quickly with a pipette and loaded into both chambers of McMaster Slide (Cat No. 6603, M/s Vet Lab Supplies Ltd., UK). The eggs counted in chambers 1 and 2 were multiplied by 17 and expressed as the number of eggs per gram (EPG) feces. Blood samples were collected from the jugular vein using a vacutainer needle into 10 ml caped ethylenediamine tetraacetic acid-coated tubes at 0, 15, 30, 60, and 90 days of age. Samples were analyzed using an auto hematology analyzer (BC-2800Vet, M/s Mindray Medical International Ltd., Shenzen, China).
Serum immunoglobulins
Calf serum IgG concentrations at 0, 2, 7, 14, 30, 60, and 90 days of age were estimated by bovine IgG by sandwich enzyme-linked immunosorbent assay kit (M/s Sigma-Aldrich, India) precoated with sheep anti-bovine Ig. The collected serum was transferred to a labeled centrifuge tube and centrifuged at a speed of 3,000 rpm for 20 minutes. The clear supernatant was collected in cryovials and stored in a deep freezer at −20°C. Samples were thawed just before the estimation of IgG and loaded in the wells. 200 μl of washing solution was added to each well and the liquids were removed by aspiration. The washing of plates was repeated thrice with 300 μl of washing solution per well. After the last wash, the residual solution was removed by inverting the plate and blotted on tissue paper. 100 μl of samples IgG diluted in the ratio of 1:100,000, 1:32,000, 1:10,000, and blocking solution (1% bovine serum albumin) were added to plates. The samples were diluted, incubated for 1 hour, washed four times as mentioned previously by adding 100 μl of diluted horseradish peroxide conjugated sheep anti-bovine IgG (1:40,000) detection antibodies (20 antibodies) and incubated for another 1 hour at 37°C. Plates were washed, and finally, 100 μl of color development reagent viz., pink-ONETMB (3,3’,5,5’tertamethyl diaminobenzidine containing 0.03% H2O2) was added to each well. Plates were incubated for 9–15 minutes at room temperature for deep blue color development because of enzymatic degradation of H2O2 by peroxidase. Each well was added with 100 μl of 2 M H2SO4 (stop solution). Optical density was checked at 450 nm against 630 nm as reference wavelength using a microplate reader. The IgG concentration in calf serum samples was calculated from the standard curve plotted for the known concentrations using a spreadsheet [11].
Symptomatic evaluation of calf diseases
The clinical signs of calf diseases were observed symptomatically daily along with the farm veterinarian for few neonatal inflictions viz., 1) diarrhea, 2) pyrexia, 3) anorexia, 4) umbilical hernia, 5) omphalitis (navel ill), 6) muzzle keratinization, 7) infectious polyarthritis (joint ill), 8) oral lesions and ulcers, 9) eye infliction and profuse lacrimation, and 10) dermatophytosis and mange. Based on FC, flotation, and FEC were considered for evaluating diarrhea. Pyrexia was diagnosed by checking the rectal temperature. Anorexia was diagnosed physically based on a reduced inclination to milk suckling, forbs nibbling, emaciation, lethargy, depression, and weight loss. The umbilical hernia was diagnosed by palpation of the intestinal loop and hernial ring in the ventral region of the abdomen. Omphalitis was interpreted from the typically hot, swollen, moist, painful area around the umbilicus and any puss-filled abscess at the site of the navel cord. Muzzle keratinization was diagnosed by physical examination of the dry ulcerative type of lesions on the muzzle, fast pain reflux of animal feeling, and reduced feed intake. Swollen, painful, and inflamed joints apart from the soft fluid-filled fluctuating puss-filled cavity around the knee joint were taken as symptoms of infectious polyarthritis. Oral lesions and ulcers were diagnosed by oral examination for blisters inside the tongue, hard palate, dental pad, lips, gums, and any ulcer due to rupture of a blister, and off-feed due to pain in the buccal cavity. Eye infection and profuse lacrimation were diagnosed from the red/pink eye, eyelid swelling, and persistent mucopurulent discharge from the eye. Dermatophytosis was assessed based on greyish lesions with a slight concave in the shave, circumscribed while mange was adjudged by scratching, inflamed skin, localized hair fall, and peaked by crust formation.
The disease risk ratio or relative risk was calculated using a 2 × 2 matrix consisting of the absolute risk of incidences and no risk of incidences in calves of CG and TG [12]. The risk ratio was calculated by the following formula:
Risk ratio=Total risk of incidences in TG/Total risk of incidences in CG.
A risk ratio of 1 was an indication of identical risk among two groups, whereas <1 or >1 was indicative of increased risk or decreased risk, respectively, in the numerator (TG) compared to the denominator (CG).
Data analysis
Data about nutritional parameters and body weight gain were analyzed by completely randomized block design to differentiate variance due to gender influence or treatment effect. FC, FEG, and serum IgG concentration between CG and TG irrespective of gender were tested by paired sample Student t-test. A nonparametric chi-square test was applied to test the significance of the risk ratio. All analyses were made using a statistical package [13].
Results
Liquid diet consumption
The liquid and solid diet consumption by calves during the neonatal and preweaning period is presented in Table 1. The colostrum quality was comparable between all the dams. The Ig concentration on day zero in colostrum was 92.51 ± 2.88 mg/ml and reduced to 39.12 ± 1.35 mg/ml after 24 hours.
On day 6, the transition milk composition was comparable to regular cow milk with total solids; 12.76 ± 0.05, milk protein; 3.18 ± 0.03, milk fat; 3.98 ± 0.03, lactose; 4.91 ± 0.03, and total ash; 0.71 ± 0.01, g/100 g. Irrespective of gender groups, the mean milk yield (Fig. 1A) of the dams in the first fortnight after calving was 2.86 and 3.13 kg/day (p=0.71) in CG and TGs, respectively, and comparable at fortnightly intervals. Calf suckling time (minute) was 5.22 ± 0.13 and 5.33 ± 0.06 in CG and TG, respectively (p=0.30). The calf suckling rate (cycles/minute) was 22.10 ± 0.82 and 23.22 ± 1.10, respectively, (Fig. 1B) in CG and TG (p < 0.05).
Table 1.
Liquid and solid diet intake in neonatal and preweaning calves.
| Parameter | Female | Male | SEM | p-value | ||
|---|---|---|---|---|---|---|
| CG | TG | CG | TG | |||
| Birth weight | 20.24 | 20.20 | 21.58 | 21.78 | 1.04 | 0.59 |
| Body weight at day 30 | 30.49 | 32.57 | 37.16 | 36.85 | 1.91 | 0.08 |
| Body weight at day 90 | 41.66 | 43.82 | 48.59 | 48.98 | 2.40 | 0.14 |
| Neonatal calves (upto 28 days after birth) | ||||||
| Milk intake (kg/day) | 1.35 | 1.50 | 1.36 | 1.56 | 0.12 | 0.54 |
| Milk solids intake (g/day) | 172 | 191 | 173 | 199 | 14.88 | 0.53 |
| Green fodder (g/day) | 225 | 232 | 230 | 232 | 3.48 | 0.42 |
| Total diet DM intake (g/day) | 397 | 424 | 404 | 431 | 15.12 | 0.38 |
| Digestible DMI (g/day) | 307 | 333 | 312 | 338 | 14.53 | 0.40 |
| Digestible CPI (g/day) | 71 | 77 | 73 | 80 | 3.85 | 0.41 |
| Digestible energy intake (Mcal) | 1.72 | 1.86 | 1.75 | 1.89 | 0.08 | 0.41 |
| Pre-weaner calves (day 29–90 after birth) | ||||||
| Milk intake (kg/day) | 1.37 | 1.42 | 1.36 | 1.07 | 0.22 | 0.69 |
| Milk solids intake (g/day) | 175 | 181 | 173 | 136 | 28.53 | 0.69 |
| Green fodder (g/day) | 375 | 385 | 388 | 383 | 7.89 | 0.69 |
| Concentrate mixture intake (g/day) | 157 | 158 | 158 | 160 | 2.33 | 0.76 |
| Total diet DM intake (g/day) | 936 | 974 | 963 | 949 | 28.91 | 0.81 |
| Digestible DMI (g/day)* | 434a | 478b | 468b | 496b | 9.03 | 0.03 |
| Digestible CPI (g/day)* | 74a | 77a | 76a | 84b | 2.37 | 0.05 |
| Digestible energy intake (Mcal)* | 2.18a | 2.36b | 2.32b | 2.45b | 0.04b | 0.04 |
*p < 0.05.
a,bValues bearing alpha superscripts in a row for a parameter differ significantly.
Figure 1.
(A) Milk yield, flow rate, let down and calf suckling time. (B) Calf suckling rate.
Solid diet consumption
The dry matter intake (DMI) from MGF during the neonatal period was on average 230 g/day (p=0.42). It was increased to 380 g/day (p=0.62) in the preweaning period, but milk consumption more or less remained the same. During preweaning, calves were fed CM besides MGF. CM intake ranged from 157 to 160 g/day on a DM basis during the preweaning period in the CGs and TGs, respectively. The ratio between MGF and CM in the total DMI was 50:50.
The total fat intake during the preweaning period was 74 and 83 g/day in CGs and TGs, respectively. The FSO intake from the whole flax seed was only 9 ml in the preweaning period in contrast to 30 ml during the neonatal period. The fat intake in calves either neonatal or preweaning age was 10% of the total DMI.
Body weight changes
The birth weight in male calves was 1.5 kg higher than in female calves, but there was no significant difference between male and female calves in CG or TGs (Table 1). The body weight changes in neonatal male and female calves of CG or TG were significant (p=0.08). The difference in body weight gain was greater in females (2.2 kg) than in male calves (400 g) at 90 days of age.
FC and FEC
The FC score in the first week of birth was not different between CG and TG (Table 2). A distinctive difference in FC score was observed from day 14 to 90 (p < 0.05 to 0.01). The FEC was statistically insignificant between CG and TG on day 15 (p=0.28), but significant (p < 0.06–0.01) from day 30. FEC was 37 and 32 EPG in the first fortnight, respectively, in CG and TG (Table 3). The odds ratio for calf diarrhea in TG was 0.3 in contrast to 0.9 in CG (Fig. 2).
Table 2.
Fecal consistency score in neonatal and preweaning calves.
| Calf age | CG | TG | SEM | p-value |
|---|---|---|---|---|
| 0 | 1.40 | 1.50 | 0.27 | 0.72 |
| 3 | 1.50 | 1.10 | 0.22 | 0.10* |
| 7 | 1.30 | 1.40 | 0.18 | 0.59 |
| 14 | 2.50b | 1.00a | 0.27 | 0.01*** |
| 21 | 2.20b | 1.20a | 0.33 | 0.02** |
| 28 | 2.20b | 1.10a | 0.43 | 0.03** |
| 45 | 2.30b | 1.50a | 0.29 | 0.02** |
| 60 | 2.20b | 1.10a | 0.42 | 0.05** |
| 75 | 2.40b | 1.20a | 0.36 | 0.01*** |
| 90 | 2.00b | 1.20a | 0.36 | 0.05** |
Values bearing different superscripts in a row differ significantly.
*p < 0.10
**p < 0.05
***p < 0.01
Table 3.
Fecal egg count in neonatal and preweaning calves (EPG).
| Calf age | CG | TG | SEM | p-value |
|---|---|---|---|---|
| 0 | 0.00 | 0.00 | - | - |
| 15 | 37.40 | 32.30 | 4.43 | 0.28 |
| 30 | 108.80a | 86.20b | 9.33 | 0.04** |
| 45 | 122.40a | 91.80b | 14.29 | 0.06* |
| 60 | 161.50a | 125.80b | 15.30 | 0.04** |
| 75 | 205.70a | 188.70b | 12.67 | 0.02** |
| 90 | 277.10a | 222.70b | 17.52 | 0.01*** |
a,bValues bearing different superscripts in a row differ significantly.
*p < 0.10
**p < 0.05
***p < 0.01
Figure 2.
Incidences of calf diseases from birth to preweaning.
Serum Igs and blood profile
The serum IgG on day 2 was 33 mg/ml in both CG and TG. Subsequently, the serum IgG was reduced to a threshold level of 20 mg/ml on day 30 (Table 4). The serum IgG was again increased to 30 mg/ml on day 90 of the birth. Neutrophils and monocytes were comparable between CG and TG (Table 5). Bovine platelets were within the normal physiological range in CG and TG. On days 60 and 90 of the calf birth, higher hemoglobin (p < 0.05) was observed in TG than in CG.
Calf disease incidences
The symptomatic analysis of calf diseases indicated that the calves in TG were less susceptible than CG. Multiple incidences were observed in the calves belonging to CG (Fig. 2). No incidences of oral lesions and ulcers, infectious polyarthritis, umbilical hernia, anorexia, and, pyrexia were observed in calves belonging to TG. Although serum IgG levels in the calves of CG and TGs were more than the suggested values [3], the relative risk of disease in TG was only 0.58 compared to 1.0 in CG (p < 0.001). The relative risk of calf incidences in TG was reduced by 42% compared to CG in preweaning age.
Table 4.
Serum Ig concentration (mg/ml).
| Calf age | CG | TG | SEM | p-value |
|---|---|---|---|---|
| 0 day | 0.54 | 0.52 | 0.06 | 0.75 |
| 2 days | 33.05 | 32.52 | 0.63 | 0.42 |
| 7 days | 26.06a | 27.60b | 0.79 | 0.08* |
| 14 days | 24.19a | 25.81b | 0.80 | 0.07* |
| 30 days | 20.83 | 21.46 | 0.67 | 0.37 |
| 60 days | 25.51 | 26.31 | 0.74 | 0.31 |
| 90 days | 29.19 | 30.07 | 0.95 | 0.38 |
a,bThe values bearing different superscripts in row differ significantly.
*p < 0.10
Discussion
Female calves with a birth weight of less than 22 kg and male calves with less than 24 kg are at a higher risk of low vigor and preweaning mortality [14]. All the calves were fed the colostrum at 10% of the body weight soon after birth and continued for 5 days without any supplements. Time factor in feeding colostrum is important because Ig in colostrum and their absorption across intestinal epithelium diminishes with time and reaches threshold levels at 24 hours [2,15]. The serum IgG is essential in neonatal calves until they develop specific adaptive functions by the fourth or fifth week of birth. The amount of serum Ig present on day 2 was higher but, diminished gradually to day 30 and was restored to 30 mg/ml on day 90. If serum IgG levels were more than 10 mg/ml soon after birth, there would be fewer chances of calves becoming ill before 14 days of life. The serum Ig levels are important to evaluate the farm’s prophylactic program [3]. A strategy to improve innate immunity is necessary until 90 days of age as serum Ig levels would diminish with the progression of age in neonates.
Calf suckling stimulates higher milk yield, particularly in zebu cattle [16]; hence, the average milk yield (kg/day) of dams during the 90 days trial period was significantly (p < 0.05) more in TG than CG. The milk letdown time in TG was higher than in CG because the calf suckling rate was significant eventhough suckling time was comparable. We noticed that the calves in TG were more athletic and active than the calves in the CG. The welfare and growth of dairy calves are better with the increased suckling of dams [17]. Contact between the mother and the young is particularly important in B. indicus cattle. Any early separation of the calf from the dam in B. indicus cattle breeds accidentally or forcibly hinders the milk let down resulting in depression, eudemonic and hedonic health, and diminished physical performance of the dam and calf.
Table 5.
Blood profile of neonatal and preweaning calves.
| Calf age | CG | TG | SEM | p-value | CG | TG | SEM | p-value | |
|---|---|---|---|---|---|---|---|---|---|
| Hemoglobin % | Leukocytes (×103/µl) | ||||||||
| 0 day | 8.16 | 8.18 | 0.14 | 0.89 | 8.4 | 8.39 | 0.31 | 0.98 | |
| 15 days | 9.59 | 9.61 | 0.17 | 0.91 | 10.27 | 10.11 | 0.54 | 0.27 | |
| 30 days | 10.59 | 10.63 | 0.38 | 0.92 | 10.84 | 10.66 | 0.39 | 0.66 | |
| 60 days | 8.94a | 10.77b | 0.78 | 0.04** | 10.48 | 10.37 | 0.79 | 0.89 | |
| 90 days | 10.20a | 11.67b | 0.53 | 0.02** | 11.02 | 10.79 | 0.57 | 0.69 | |
| Erythrocytes (×106/µl) | Monocytes (%) | ||||||||
| 0 day | 8.47 | 8.48 | 0.31 | 0.98 | 1.0 | 1.1 | 0.10 | 0.34 | |
| 15 days | 9.33 | 9.73 | 0.66 | 0.56 | 1.0 | 1.1 | 0.10 | 0.34 | |
| 30 days | 8.78a | 9.77b | 0.26 | 0.01*** | 0.7 | 0.8 | 0.10 | 0.34 | |
| 60 days | 9.82a | 11.69b | 0.78 | 0.04** | 1.1 | 1.2 | 0.10 | 0.34 | |
| 90 days | 9.84a | 12.19b | 0.97 | 0.04** | 1.1 | 1.3 | 0.20 | 0.34 | |
| Lymphocytes (%) | Neutrophils (%) | ||||||||
| 0 day | 43.10 | 44.70 | 1.34 | 0.26 | 19.0 | 19.3 | 1.01 | 0.77 | |
| 15 days | 45.60 | 46.50 | 0.60 | 0.17 | 26.0 | 27.3 | 1.25 | 0.32 | |
| 30 days | 42.60a | 46.80b | 1.78 | 0.04** | 30.0 | 31.0 | 1.19 | 0.42 | |
| 60 days | 51.10a | 57.80b | 2.92 | 0.05** | 35.6 | 36.9 | 1.43 | 0.39 | |
| 90 days | 51.80a | 59.10b | 2.736 | 0.03** | 41.4 | 42.8 | 1.15 | 0.25 | |
| Eosinophils (%) | Platelets (×105/µl) | ||||||||
| 0 day | 2.1 | 2.0 | 0.10 | 0.34 | 298.8 | 309.5 | 8.98 | 0.26 | |
| 15 days | 2.0 | 2.3 | 0.21 | 0.19 | 372.0 | 391.8 | 28.64 | 0.50 | |
| 30 days | 2.0 | 2.2 | 0.2 | 0.34 | 411.7a | 467.8b | 30.39 | 0.09* | |
| 60 days | 2.0 | 2.2 | 0.2 | 0.34 | 446.4 | 489.2 | 36.30 | 0.27 | |
| 90 days | 2.4 | 2.5 | 0.1 | 0.34 | 485.7 | 516.0 | 63.66 | 0.64 | |
Values bearing different superscripts in a row differ signficantly.
*p < 0.10
**p < 0.05
***p < 0.01
Drenching FSO after 28 days of age was discontinued owing to the lesser impact of reflux closure of the esophageal groove. During the preweaning period, jaggery was provided to improve soluble carbohydrates to support better rumen microbial growth [18], as 90% of rumen development and 90% of rumen microflora establishment takes place in the calf by 60 days of age [15]. The total DMI in CG and TGs was comparable in the neonatal period when the additional supplement fed to TGs was substracted. The calves started to nibble the MGF from day ten. The nutrient digestibility between groups was statistically comparable during neonatal and preweaning periods.
The body weight gain was analyzed as per the sex of the calves in CG and TGs. Although male and female neonates were equally poised for calf diseases, the response of nutritional intervention for apparent body weight gain was higher in the female than in the male calf. In the later stages of growth, male calves grow faster than female calves but during the neonatal period, female calves show better growth response. Better weight gains in female calves in the early age is important for their life time performance. The body weight gain in preweaner calves after the neonatal period was nonsignificant between male and female calves of CG and TGs. The response to the supplementation of FSO in neonatal calves was better than preweaner calves.
FC, FEC, and diarrhea risk observed in CG is a global problem in the cattle industry due to the multifactorial nature of the disease. Although the EPG was significantly lesser in TG than in CG after 30 days of age, it was more than 50 in both cases and was considered high. In calves, FEC of less than 20 EPG is encouraged. A management and prophylactic program should have a strategy to contain the FEC below 20 EPG. The FC score was better in TG than in CG. Calves in TG were at a lower relative risk than CG. Few oils have the property to relieve diarrhea and improve intestinal flora composition. No correlation between FC and calf hide cleanliness scores was reported [19]. A good understanding of the disease’s complexity due to multiple pathogens, co-infection, and environmental factors, including nutrition and management, is necessary to prevent diarrhea. Dehydration during diarrhea or acidosis in calves is a predisposing factor for anorexia and ataxia [20]. Drenching FSO did not show much effect on FEC, but it was 15%–30% less than CG until the sixth fortnight. Calves under confinement have more chances to harbor parasitic infections related to whipworms, threadworms, hookworms, tapeworms, and so on [21]. FEC is considered to provide precision information to curtail gastrointestinal parasitism in calves. The relative risk of diarrhea was reduced by three times in TG due to supplementing FSO.
The comparable IgG levels in CG and TGs have equal opportunity to innate response with adaptive specificity of IgG. Many human and animal experiments proved that the PUFA from plant or fish oils are important modulators of the immune system [22]. Transcriptomic studies conducted on cows fed with linseed oil has been reported to preferentially upregulate the pathways associated with cell organization together with cell function, nutrient, energy metabolism, and immune system functions [23]. The innate reaction in neonates is limited mainly to the neutrophilic release of reactive oxygen species and phagocytosis, which can result in excessive inflammation and damage to host tissues [24]. Neutrophils and monocytes were comparable between CG and TG; hence, monocytes and macrophages mediated disease response is also presumed to be identical [25]. In neonates, PCV, hemoglobin, and erythrocytes are least related to colostrum or its time of feeding. More leukocytes in CG than in TG indicated disease prevalence associated with inflammatory processes and stress [26]. Bovine platelets are in general, smaller than other species. They were found to be within the physiological range and can survive up to 10 days in circulation.
The relative risk of calf incidences in TG was reduced by 42% compared to CG in preweaning age. due to FSO supplementation that has anti-inflammatory, antipyretic, antioxidant, and analgesic effects due to the presence of omega 3 and 6 fatty acids [8]. The B. indicus calves were also equally susceptible to different calf incidences such as Bos taurus calves because all ruminants acquire passive immunity only after birth from the colostrum feeding and develop innate immunity subsequently [6,14]. FSO supplementation helped to improve the resilience of newborn calves compared to CG.
Conclusion
Supplementing FSO 30 ml/day as a source of PUFA in the newborn calf from day 6 to 28 followed by ground flax seed bolus improved the FC, reduced FEC, and significantly reduced diarrhea. The relative risk of calf incidences was reduced by 42% with PUFA supplements besides improvement in hemoglobin, erythrocytes, and lymphocyte count in blood. FSO supplementation could be adopted to reduce morbidity, and mortality, and improve disease resilience and body weight gain in neonates and preweaning calves.
Acknowledgment
The authors thank the Director, ICAR-National Dairy Research Institute, for extending the facilities and financial support.
