The early separation of the calf from the cow is common in the dairy industry and is deemed by some to be essential to maximum production [1
]. However, it is expected that the delayed separation of calf from mother may improve welfare and growth of dairy calves. Under ecological or organic conditions, cow and calf remain together until weaning at 6–8 months [1
]. In contrast, on many commercial dairy farms, calves are abruptly separated from cows within a few hours of birth [3
]. Dams return to the milking herd while calves are artificially reared in isolation or in groups. Calves are fed rationed quantities of milk or milk replacer (MR) until weaning from milk nutrition, approximately 4–12 weeks [6
In past years, a number of authors have explored different ways of keeping dairy cows and calves together [1
]. They found possible benefits of these manners as calf growth and behavioural development. The suckling systems can be divided into more different categories depending on the farming type purpose and duration of the suckling period [7
Some suckling systems restrict the contact between mother and young to half the day or to short periods after milking, only; others allow 24 h/d contact. Restricted suckling means that the calf is allowed to suckle its own dam during short periods daily. Cow and calf may stay together for 2 × 15 min [9
] or 2 × 30 min [11
]. For the rest of the day, cow and calf are separated [8
]. The cow calf contact system implies that 2–4 calves are kept together and suckle one nursing cow [1
]. The ratio of nurse/foster cows to calves should be adjusted so that each calf receives at least 4–6 kg/day of milk. All calves should be matched for age and body weight [8
]. Calves may be with wiped amniotic fluid or transfer odour prior to discharge to a cow [15
For many years, ad libitum (ADL) whole milk or MR feeding is propagated in calf rearing [1
]. Authors found the large discrepancy between the low amount of milk usually fed to calves on farms and the large amount of milk that the calves will drink when allowed to suckle ADL from their dam or nurse cow [8
]. Restrictive suckling calves often consumed less milk than those reared artificially by the automatic milk-feeder or in the nipple buckets Consumption of milk in calves which are allowed to suckle depends on milking, time suckling, and whether there is more than one calf [22
Compared with calves provided ADL milk, calves fed restricted amounts of milk have greater rates of concentrate mixture (CM) intake [23
]. On the contrary, the CM intake was higher in the calves receiving milk than those fed MR [25
]. Also, calves fed high amounts of MR usually present low CM intake [26
]. Calves artificially reared ate more CM than those under restrictive suckling [18
Generally, calves on a low milk allowance had a significantly lower growth than the calves on high milk allowance [30
]. Also, the prolonged period of nursing increased calf average daily gains (ADG) during the milk-feeding period [33
A number of articles report a higher ADG in ADL fed calves or restricted-suckling (2 × 30 min after milking) than in artificial reared calves (nipple bottles or buckets at the same time) [11
]. It is important, how much MR given to artificially reared calves. However, some authors found no difference or lower ADG [12
The objective was to determine the impact of the calves rearing, gender, and the sire lineage on the growth and health. We tested a hypothesis that dairy calves’ growth and health are influenced by the rearing manner (Single suckling, SS; Multiple suckling, MS; Artificial rearing by nipple of bucket sucking, hutches, H), gender, and the sire lineage.
2. Materials and Methods
The study was performed in Nitra, Slovakia. The experimental period lasted for 360 days, but the whole experiment lasted 16 months. Each calf was evaluated for 360 days. We could not include all animals in the experiment at once, so the whole experiment was extended to 16 months. Males and females were 360 days in the experiment.
2.1. Animals and Treatments
At the birth, 105 Holstein calves (53 males and 52 females, descended from 4 sires) were consecutively assigned into the three treatments groups, balancing for gender but not sire or birth weight.
Group SS (n = 36, 18 males, 18 females) were housed separately in a common individual pen with the mother (milked from 2nd day at 05:00 and 16:00) until the 21st day; suckled their mother’s udder 10 min 3 times per day (8:00, 13:00, 18:00), then let loose in a housing pen from the 22nd day (6 kg any cow milk per day, 2 × daily 3 kg, bucket with nipple). The health condition of SS cows was checked precisely. Disease occurrence was recorded by researchers (each day) and the project veterinarian who examined the animals clinically (every second morning). Group MS (n = 34, 17 males, 17 females), after 3 days kept with their own mother in individual pens, were then put in pens with non-milked nursing cows from the 4th day; calves could suckle at any time, usually 3–5 times per day. A total of 14 cows were used, of which 5 for 2nd parity, 7 for 3rd parity and 2 for 4th parity. Ten cows were in the mid lactation stage and 4 in the late lactation stage. Nursing cows were selected from milking cows of the herd. Their health and udder health status were checked before the start of the experiment, they had to be perfectly healthy and their temperament had to be mild. During the experiment, their health and udder health status were checked once a week. They had no health problems.
Group H (n = 35, 18 males, 17 females), after having nursed their dams in individual pens for 24 h in hutches from the 2nd to 56th day (bucket with nipple, MR, 2nd day 3 × 0.5 kg, 3rd day 3 × 1.0 kg, 4th day 3 × 1.5 kg, from 5th day 6 kg/day, to 21st day 3 × daily), were then kept in loose housing pens to wean from the 57th day (bucket with nipple, MR, 6 kg/day, 2 × daily).
Experimental calves originated from four sires (S1, S2, S3 and S4). The distribution was as follows: SS (S1 = 8, S2 = 5, S3 = 14, S4 = 9); MS (S1 = 3, S2 = 10, S3 = 15, S4 = 6) and H (S1 = 5, S2 = 9, S3 = 12, S4 = 9). By gender, this represented: males (S1 = 9, S2 = 10, S3 = 20, S4 = 14) and females (S1 = 7, S2 = 14, S3 = 21, S4 = 10). All animals were weaned abruptly at the age of 12 weeks and moved to a group housing pen, where equal conditions of nutrition were ensured. The transfer was made at the exact age of 84 days. Each treatment group separate pens for males and females, also pens were differentiated by age, so that the age difference in one pen was not higher than 21 days. Approximately 10–15 calves were kept in a pen of 9 × 4.5 m.
2.2. Feeding Managements and Experimental Procedures
Calves in all groups were kept in individual pen with mother and received colostrum for the first 24 h by suckling ad libitum. If some calves did not want to suckle, they were fed with a teat-bottle (two hours after the birth).
From the 2nd day until weaning the calves were offered starter concentrate mixture (SCM) and alfalfa hay ADL.
Consumed amounts of milk, MR, and other feeds were taken from 4th to 84th day. Suckling time a mother’s udder (10 min) of SS calves was determined during preparation on experiment according to [41
]. We wanted to know how much milk will be available to the calf during suckling. The calves were weighed immediately before and after each suckling to assess milk intake. For 3 × 10 min, the calf should receive 6 kg of milk from the average herd cow. At current experiment, these SS calves were also weighted before and after each suckling.
Number of MS calves per nursing cow was determined according to milk yield of selected cows, so that 6 kg of milk per calf and day should be available. All designated calves were well adopted by the cows. The adoption criterion was when the cow allowed the calf to suckle in the inverse parallel position and licked it. No amniotic liquid had to be used. Milk yield controls were performed on the last day before moving to the experiment and then weekly thereafter. It was not possible to measure milk consumption at MS calves at every suckling event.
Milk replacer (Lactavit12, MILKP Slovakia) consumption in H group calves was taught by weighing at every individual drink (to 21st day 3 × daily, hutch; from 22nd day 2 × daily, hutch and then group housing from 57th day to weaning at 84th day, 2 × daily).
The SS and MS calves could eat SCM and alfalfa hay from a special feeder ADL, the calves had no access to feed the cows from the trough. Cows could not eat from the calves’ feeder. The H group calves received SCM from a bucket and alfalfa hay from crib feeder. Feed refusals were removed and weighed each morning before feeding throughout the whole milk-feeding period. All calves offered the same SCM and forage.
After weaning, feed was available throughout the 24 h periods. Calves were fed alfalfa hay and corn silage ADL and 1.5 kg/day of SCM (TKS, PZa Slovakia) from a group feeder, but the intake was not recorded.
From 181 days, the bulls and heifers in all three groups were fed the same total mixed feed ration (TMR) throughout the study. The CM (used from 181 to 360 days, 1.5 kg/day) was fed separately. The consumption was not recorded. Drinking water was available at all times throughout the study.
The cows’ SS and MS groups were fed the TMR. The Feed ration contained 16.5 kg of dry matter (DM), 104.1 MJ net energy content for lactation (NEL), 1.44 kg of protein digestible in the small intestine (PDI) and 2.32 kg of crude protein. The TMR was administered to troughs by a feeding wagon. Feed troughs were raised 0.68 m above ground. The cows did not receive concentrates separately. Feeding was allowed throughout the 24 h period. Automatic watering troughs were located next to feed bunks. The total mixed ration was calculated according to Slovakian nutrient requirements of dairy cattle [42
The methods of Larson et al. [43
] and Slavik et al. [44
] for the daily evaluation of the health (e.g., diarrhoea, respiratory condition, mastitis, laminitis) was used. For the expression of diarrhoea, colour and consistency of faeces (i.e., yellow, code 0; green, code 1; white, code 2; red, code 3; pink, code 4; brown, code 5; dark or black, code 6) and consistency (i.e., liquid, code 0; normal, code 1; firm, code 2) was used.
Live body weight (LBW) of the calves was recorded at birth. All calves were weighed every week and then every month after weaning. The ADG is the rate of live weight gain per day over some period of time. It was calculated as the average change in live body weight during a specified period. The calves were weighed on the plate scale with LCD display (Soehnle, Germany), load capacity up to 200 kg and weighing accuracy +/− 0.1 kg. The live body weight of young cattle was determined to mobile livestock scale (DVM, Soehnle, Germany), load capacity up to 2000 kg and weighing accuracy +/− 0.2 kg.
2.3. Housing of Animals
Group SS was kept in individual pens of 4.5 × 4.5 m, one cow, one calf. A small part of the pen was separated for calf (1.2 × 4.5). The cow and the calf were loose.
Group MS was housed in a pen of 9 × 4.5 m (3 nursing cows and 10–12 calves). Cows were tied in the pen, and the calves were loose.
Hutches (group H) were made from fibreglass (white colour), used from the second day of life to relocation to group housing at the age of 8 weeks. Each hutch (1.8 × 1.2 m) had an outside fenced yard of 1.8 × 1.2 m, bedded with straw. Hutches were arranged in rows, 0.8 m apart.
The calves could see and touch each other through the openings in the upper part of the pen wall or fenced yard of the hutch. Each calf had free access to clean drinking water in a plastic bucket or automatic drinker throughout the study.
After weaning from milk feeding, all calves were separated by sex in age-balanced groups in loose housing bedded pens with the same ration. The calves had no visual contact with the dam or nursing mother, only acoustic.
The SS cows were milked twice a day at 05:00 and 16:00 after being driven by the herdsman a short distance within the barn to a holding area, which measured 13.5 m × 4.5 m, adjacent to the milking parlour. Cows entered the parlour individually once a milking stall was available. Upon exiting the parlour, cows remained in a separate holding area until all other cows in the group were milked.
2.4. Chemical Analyses
The MR (Lactavit12), SCM (TKS) and CM (KSJ) were analysed in the PZa Slovakia. Cow milk, alfalfa hay, corn silage, also feeds for TMR were analysed in the Nutrition laboratory of National Agricultural and Food Centre, Luzianky, Slovakia. Samples feeds were examined for DM (at 105 °C) and crude protein (Kjeldahl N) using Kjeltec Unit. Ether extract (using a Soxtec System, Tecator, Sweden) and ash (using at 550 °C) were determined according to AOAC (2000) while determination of crude fibre, neutral detergent fiber (NDF), acid detergent fiber (ADF) and acid detergent lignin (ADL) was carried out using a Fibertec 1010 (Tecator, Hilleroed, Denkmark). Starch was determined on polarimeter ADP 220. For macro and micro elements analysis sample were burned at 550 °C, the ash was dissolved in 10 mL of HCl (1:3) and minerals were determined by Unicam AAS spectrometer iCE 3000 (Thermo Fisher Scientific, Waltham, USA), phosphorus content was determined by molybdate-vanadate reagent on CamSpec 501 (Spectronic CamSpec Ltd., Leeds, UK). Value of pH was determined using electrometric method, lactic acid and volatile fatty acids (acetic, propionic and butyric acid) content was determined by gas chromatography and alcohol content by micro-diffusion method.
Chemical composition of the solids in cow milk was crude protein 278.6 g/kg DM, crude fat 323.6 g/kg DM, lactose 342.6 g/kg DM, and ash 57.6 g/kg DM. The MR (DM 94.7%), was composed of dry whey, dry buttermilk, dry skimmed milk, animal fat, whey dried with vegetable oil, and wheat gluten (crude protein 226 g/kg DM, crude fat 196 g/kg DM, ash 87 g/kg DM and crude fibre 6.0 g/kg DM). The SCM (DM 89.3%) contained barley, wheat, soybean meal, oats, corn and mineral mixture (crude protein 214 g/kg DM, crude fat 32 g/kg DM and ash 81 g/kg DM). The CM (DM 90.1%) contained sunflower cake, cotton seed cake, corn, wheat bran, mineral mixture, salt (crude protein 183 g/kg DM, crude fat 35 g/kg DM, and ash 92 g/kg DM).
Composition of alfalfa hay (DM 88.8%) was crude protein 212 g/kg DM, total digestible nutrients 595 g/kg DM, acid detergent fibre 294 g/kg DM, neutral detergent fibre 351 g/kg DM, Ca 13.8 g/kg DM, and P 2.6 g/kg DM. Composition of corn silage (DM 43.21%, pH 4.06) represented crude protein 68.6 g/kg DM, starch 406 g/kg DM, non-fibrous carbohydrates 518 g/kg DM, sugar 12.0 g/kg DM, crude fat 33.4 g/kg DM, acid detergent fibre 232.8 g/kg DM, neutral detergent fibre 345.1 g/kg DM, ash 51.8 g/kg DM, Ca 2.2 g/kg DM, P 2.3 g/kg DM, Mg 1.5 g/kg DM, K 9.3 g/kg DM and S 1.3 g/kg DM).
2.5. Statistical Analyses
The data were analysed using a general linear model ANOVA (AOV/AOCV) by the statistical package STATISTIX, Version 10.0. The dependent variables were LBW, ADG, consumption of feed to weaning, colour and consistency of faeces and the independent variables were treatment group (T), gender (G) and sire lineage (S).
The normality of data distribution was evaluated by the Wilk–Shapiro/Rankin Plot procedure. The homogeneity of variance of the observed variables in groups was calculated by preliminary variance tests which determined whether the variabilities were equal. The Bartlett’s test for the equality of variance tests was used for an unequal size of samples. Differences among groups were tested by comparisons of mean ranks. Significant differences among means were tested by Bonferroni’s test.
All values are reported as means ± standard deviation. The interactions among observed factors (treatment, gender and sire lineage) were also computed.
The following model of general AOV/AOCV on observed factors (treatment and sire lineage) was used:
Yijk = μ + Ti+ Gj + Sk + αij + βik + γjk + εijk
where Yijk is a dependent variable, μ is the overall mean, Ti is the effect of factor treatment on the level i, Gj is the effect of factor gender on the level j, Sk is the effect of factor sire lineage on the level k, αij is the interaction between factor T on the level i and factor G on the level j, βik is the interaction between factor T on the level i and factor S on the level k, γjk is the interaction between factor G on the level j and factor S on the level k and εijk is the residual error.