Feeding behavior of early weaned lambs deprived of roughage

*Corresponding author: Miroslav Simeonov, Department of “Preservation, Quality Evaluation and Utilization of Forage Crops” Research Institute of Forge Crops, Pleven, 5800 Bulgaria. E-mail: msimeonov78@abv.bg. Tel: +359 / 878 632 156. Fax: +359 / 64 805 881 Received: 05 May 2015; Revised: 09 November 2015; Accepted: 16 November 2015; Published Online: 16 November 2015 R E G U L A R A R T I C L E Simeonov, et al.: Feeding behavior of early weaned lambs 920 Emir. J. Food Agric ● Vol 27 ● Issue 12 ● 2015 et al. (1999), leads to higher degradation of organic matter in dairy cows. Times of the day, combined with the temperature, also affect feeding behavior. However, alone the time can-not be used as an indicator of feed consumption (Pinto et al., 2010). When temperature is elevated eating decreases the lambs during the period from 12 to 16 hours when the temperature is higher than remainder of the day (Keskin et al., 2010). The aim of the present study was to trace the feeding behavior of early weaned lambs deprived of roughage compared with lambs that were fed alfalfa hay ad libitum. MATERIALS AND METHODS The study was conducted at the Institute of Forage Crops in the town of Pleven, in February 2011, with 12 early weaned lambs of the Blackhead Pleven Breed. The lambs were weaned with a live weight of 9.261 kg at the age of 19.6 days (Simeonov, et al, 2015). Following the weaning, the animals were distributed into two groups (6 animals per group), equalised in terms of the parameters of live weight, age, sex and type of birth (single or twins). The animals in each group were distributed into three subgroups (2 lambs in each) and accommodated within boxes with dimensions 3 m × 1.5 m, that is sufficient to to their free movement, feeding and lying. The feeder and the drinker in boxing were constructed so as to allow daily cleaning, washing and disinfection. Parameters of temperature and relative air humidity premises were: 17°C (norm from 15 to 17°C) and a relative air humidity – 65% (norm from 60 to 75%), the rate of air movement was: 0.2 m/s – in winter (norm to 0.2 m/s). The concentration of ammonia in premises was 5 mg/m3 (norm to 10 mg/m3). Front for the feeding a lamb was – 0.25 m, and front for drinking -0.03 m. It was natural lighting with luminous coefficient 1:10, at night – artificial lighting with an intensity 15 – 16 lx (norm from 15 to 16 lx). The noise level was 25 dB (norm to 50). During experimental period, the lambs of the first group were deprived of roughage (alfalfa hay), and animals from the second group received alfalfa hay freely. The lambs of both groups received pelleted protein concentrate (PPC) and wheat at a ratio 1:1 freely. The experimental period had a duration of 66 days, up until reaching 26 kg of live weight for each animal. During the experimental period, video recording of the lambs’ feeding behaviour (feeding, ruminating, lying down and standing, plus playing) was conducted for four consecutive days, from 8:00 AM to 8:00 PM, in order to encompass the 12-hour light part of the day, at an average live weight 15.7 kg. For this purpose, the animals were numbered with alkyd paint on their backs, which facilitated the individual tracking and registration of feeding behaviour (feeding, ruminating, lying down and standing, plus playing). Throughout the period of observation, the amount of feed intake was registered for both groups of lambs. The feeds were given to the lambs 3 times a day (in the morning at 8:00 AM, at noon at 12:00 AM, and in the afternoon at 4:00 PM). On the grounds of the video recordings and the time measurement of the separate stages of feeding – feed intake, ruminating, lying down, standing and playing, as well as the average amount of feed intake (respectively, dry matter), the time for intake and the time for ruminating 1 kg of dry matter were calculated on the basis of grams of intake DM for 1 minute and the influence of the intake DM on the duration of ruminating. The amount of feed intake, respectively energy and nutrients, is indicated in Table 1 and Table 2. Pearson’s correlation was calculated with the software application Statistica for Windows (2006). The significance among the groups was calculated via the t-test, with the differences being significant at P<0.05 and P<0.01. Table 1: Content of experimental rations Feeds Group 1 Without roughage Group 2 With alfalfa hay Alfalfa hay (g) 0.210 (20.9%) PPC (g)* 0.322 (36.5%) 0.355 (35.4%) Wheat (g) 0.560 (63.5%) 0.439 (43.7%) Total feed intake (g) 0.882 1.004 Feed intake in dry matter (g) 0.775 0.886 *Pelleted protein concentrate Table 2: Chemical composition and energy contents of experimental feeds Chemical composition Group 1 Without roughage Group 2 With alfalfa hay Dry matter (g) 878.5 882.7 Feeding units for growth* 1.203 1.184 Crude protein (g) 153.2 174.6 Protein digestible in intestine (g) 89.9 101.3 Protein balance in the rumen (g) 13.8 39.6 Crude fibre (g) 47.4 104.3 Crude fats (g) 14.7 16.8 Mineral substances (g) 39.0 53.8 Calcium (g) 3.894 6.281 Phosphorus (g) 4.891 4.971 *1 Feed units for growth=6 MJ NE Simeonov, et al.: Feeding behavior of early weaned lambs Emir. J. Food Agric ● Vol 27 ● Issue 12 ● 2015 921 RESULTS Throughout the observation period, the lambs deprived of roughage intake 10% more concentrated feed, compared to the animals of the second group, which received alfalfa hay (Table 1). The alfalfa hay represented only 20.9% of the total amount of intake feed in the second group, which is the reason why they intake 12.5% more feed, compared to the animals deprived of roughage (Table 1). Lambs deprived of roughage made fewer attempts to feed (P<0.05, Table 3), which has reduced the total time for eating by 94.8 min, compared to the animals receiving alfalfa hay (P<0.01, Table 3). The speed of feed intake was greater in lambs deprived of roughage, yet the duration of feeding was significantly lower (Table 3). The lambs in the group receiving alfalfa hay had 38.9% more ruminating periods, compared to the animals deprived of roughage, which has an insignificant influence on the total ruminating time. Deprived of roughage, the lambs ruminate the intake DM faster, which affects the shorter chewing time (feeding and ruminating). In this case, depriving the lambs of roughage was the reason why they spent 206.7 min less chewing (P<0.01), which increased the intake of DM and the speed of chewing it, yet decreased the time necessary for feeding and ruminating by 191.5 min (P<0.01, Table 3). The number of feedings in lambs deprived of roughage showed a high positive correlation (r = 0.930, P<0.01) with the time of consuming 1 kg of DM and a high negative correlation with the DM intake speed (r = -0.887, P<0.05, Table 4). In the lambs of the same group moderate negative correlation between the number of feedings and the total ruminating time and the time of intake and ruminating the intake DM was observed (P<0.05, Table 4). Such dependencies were not observed in the animals from the second group, which received alfalfa hay. In both groups of lambs, the feeding time had a very high positive correlation with the time of intake 1 kg of DM (P<0.01), a very high negative correlation with the rate of DM intake (P<0.01) and a high negative one with the duration of one ruminating period (P<0.05, Table 4). The number of ruminating periods in lambs deprived of roughage had a very high negative correlation with DM Table 3: Feeding behaviour of lambs Parameters Group 1 Without roughage Group 2 With alfalfa hay Significance Number of meals per 12 h 28.7±3.018 41.7±2.179 ** Time spent feeding, min 113.8±12.268 208.6±16.157 ** Time for intake of 1 kg DM (min) 146.8±15.829 235.4±19.522 ** Speed of intake (g DM/min) 6.8±0.702 4.2±0.489 * Duration of meal (min) 4.0±0.190 5.0±0.521 NS Number of ruminating periods 10.2±1.778 16.7±1.358 * Total time spent ruminating (min for 12 h) 144.5±31.751 256.4±20.659 * Duration of 1 ruminating period (min) 14.2±1.131 15.3±1.465 NS DM intake (g)/ruminating (min) 5.4±0.397 3.5±0.284 * Total time spent chewing (feeding+ruminating) (min for 12 hours) 258.3±23.398 465.0±26.782 ** DM intake (g)/chewing duration (min) 3.0±0.297 1.9±0.126 ** Time necessary for intake and ruminating of kg/DM (min) 333.3±30.190 524.8±30.228 P<0.05; **P<0,01; NS: Not significant Table 4: Correlations between the feeding behaviour of lambs, depending on the number and time of feedings Feeding behaviour Group 1 Without roughage Group 2 With alfalfa hay NF FT NF FT Time for intake 1 kg DM, min 0.930** 1.000** 0.509 1.000** Rate of intake (g DM/min) −0.887* −0.985** −0.386 −0.981** Feeding duration (g DM/min) −0.200 0.170 0.023 0.870* Number of ruminating periods −0.762 −0.720 0.293 0.624 Total ruminating time (min for 12 hours) −0.852* −0.785 −0.620 −0.364 Ruminating period duration (min) −0.923 −0.836* −0.749 −0.775* DM intake, g/ruminating (min) 0.875* 0.857* 0.629 0.328 Total chewing time (min) −0.669 −0.540 0.018 0.696 DM intake (g)/chewing duration (min) 0.659 0.550 0.061 −0.652 Time necessary for intake and ruminating of kg/DM (min) −0.669 −0.540 0.018 −0.696 NF: Number of feedings; FT: Feeding time, min; *P<0.05; **P<0.01 Simeonov, et al.: Feeding behavior of early weaned lambs 922 Emir. J. Food Agric ● Vol 27 ● Issue 12 ● 2015 intake and the duration of its chewing (P<0.01, Table 5). The total chewing time and the time required for intake and ruminating had a very high positive correlation with the number of ruminating periods (P<0.01), while in lambs receiving alfalfa hay, this dependency was high (P<0.01, Table 5). The total time of ruminating periods in the lambs deprived of roughage had a very high negative correlation with the number of feedings, the time for intake and ruminating of the DM, as well as with intake DM and the duration of chewing it (P<0.01, Table 5). A very high dependency between the total time for ruminating and the time necessary for consuming and ruminating 1 kg of DM wa