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The effect of different starters on performance and physiological characteristics of early-weaned female Holstein calves

The objective of this research was to determine the effect of different starters consisted of dried whey and soy proteins with low anti-nutritive factors (ANFs) + amino acids (lysine and methionine) on body measurements, biochemical parameters, and feed consumption of early-weaned female Holstein calves. Based on the starter, calves were divided into four groups: i) control (control starter), ii) E1 (starter with added dry whey), iii) E2 (starter with added soy proteins with low ANFs + lysine and methionine), and iv) E3 (starter with added dry whey and soy proteins with low ANFs + lysine and methionine). Results indicate that different starters based on whey powder and soy proteins with low ANFs + lysine and methionine significantly affected the consumption of milk replacer and starter, the total consumption of dry matter, then withers in height, and body length (among body traits) as well as NEFA (among blood biochemical parameters) of female Holstein calves. Finally, starters based on dried whey and soy proteins with low ANFs + lysine and methionine could be recommended to optimize the growth and feed consumption.


Introduction
During the process of rearing dairy calves, the use of adequate feeding technology can improve efficiency and economy of dairy cattle farming. According to Tozer and Heinrichs (2001), initial phase of rearing with liquid feed is the most expensive phase in the dairy business, representing approximately a fifth of a dairy farm's total cost. Drackley (2008) emphasized the importance of physical and metabolic development of reticulorumen since it provides an easier transition from pre-ruminant to mature ruminant state. Furthermore, Davis-Rincker et al. (2011) concluded that fast development of the digestive system is important for good immunological status of an animal, since it influences a long-term animal performance.
The consumption of solid feed in calf starter can affect ruminal epithelial development by altering microbial fermentation and products (Suarez et al., 2007;Khan et al., 2007a). This practice could increase butyrate production in the rumen and volatile fatty acid (VFA) which is responsible for development of epithelial tissue in reticulorumen (Bergman, 1990;Hill et al., 2006). The pre-weaned calf relies on lactose and fat as the primary energy sources, while supplementation of VFA is crucial for weaned ruminants. Baldwin and Connor (2017) pointed out the importance of the development of the pre-weaned calves for the absorption of VFA from the diet. Morrill and Dayton (1974) concluded that concentrate with up to 10 % of whey powder can increase feed intake in young calves. Inclusion of lactose in the feeding process can increase the ruminal butyrate concentration (DeFrain et al., 2006;Oba et al., 2015), and can also increase the dry matter intake in mature cows (DeFrain et al., 2004). Seagusa et al. (2017) indicated that lactose inclusion up to 10 % of dry matter in calf starters did not affect the dry matter intake as well as growth performance of calves. On the other hand, they find out that higher lactose content and hay intake might be associated with decreased severity of sub-acute ruminal acidosis (SARA). Furthermore, according to Movahedi et al. (2016), growth performance of dairy calves can differ depending on forage sources that were used. According to those authors, the use of starter plus dried sugar beet pulp flakes in comparison with the other forages, can be a valuable source of forage for dairy calves during the transition from liquid to solid feed. Lallés et al. (1996) noted that soya bean meal (SBM) is often used as plant protein source in calf starters, but SBM contains anti-nutritive factors (ANFs) and allergens such as trypsin inhibitors, glycinin, β-conglycinin, and oligosaccharides. Tukur et al. (1993) reported that β-conglycinin is very resistant to digestion of the young calf.
Body measurements could be used for growth monitoring of female dairy cattle, primarily for estimation of body weight (Heinrichs et al., 1992.)  The objective of this study was to evaluate the effect of the different feeding groups (including dried whey and soy proteins with low ANFs + lysine and methionine in the diet) on starter consumption, body measurements and blood biochemical parameters of early weaned female Holstein calves. It was hypothesized that whey and soy proteins with low ANFs would ensure dairy calves the easiest transition from milk replacer to solid feed by easier accessible nutrients.

Material and methods
The research was performed on a commercial dairy cattle farm in East Croatia. Twenty Holstein female calves with an average birth weight of 40.03±2.66 kg were selected and randomly allocated into 4 groups (5 calves per group). The experiment lasted until an average calf's age of 91 days. All calves had the same feeding plan during the experiment. They were fed with 4 L of colostrum within 2 h after birth. After administration of colostrum by drench, calves were fed first three days with non-pasteurized whole milk from transition cows (3 L twice a day). After that, they were fed with a solution of milk replacer (143 g/L of water) according to the feeding scheme presented in Table 1. From the 4 th day of life, calves had ad libitum access to water and solid feed.
Based on given starters, calves were allocated into 4 groups as presented in the Table 2. Ingredients and nutrient composition of fed starters are shown in Table 3.
After weaning, each group of calves was fed with the same starter they ate before weaning till an average of 63 days of life. Then, all calves in the experiment were eating the same total mix ration (TMR).
The measurements of the traits analysed in this research were performed two times, at 50 days and at 91 days of age. Body measures were obtained using Lydtin's rod (wither height, hip height, body length, chest depth, and chest width) and measuring tape (hip-width, heart girth, and cannon bone circumference). For biochemical analysis, blood samples were taken and blood plasma was separated. Blood plasma samples were analysed on a biochemical analyser OLYMPUS AU 400 and the following parameters were determined: gamma-glutamyltransferase (GGT), glucose, urea, total protein, albumin, iron, phosphorus, calcium, non-esterified fatty acids (NEFA), β-hydroxybutyric acid (BHBA) and insulin-like growth factor 1 (IGF-1). Finally, the consumption of the milk replacer solution (difference between the amount of offered and unconsumed) and the starter was monitored every day.
Analysed traits (body measurements, biochemical parameters, and consumption) in different feeding group (C, E1, E2, end E3) were tested separately for each measurement (I., and II.) using least square means in GLM procedure in SAS (SAS Institute Inc., 2000). Following statistical model was used: Where: y ijk = estimated trait (body measurements, biochemical parameters and consumption); µ = intercept; b 1, b 2 = regression coefficients; a i = age at measurement; T j = fixed effect of feeding group j (j = C/E1/E2/E3); e ijk = residual. Scheffe's multiple comparisons in PROC GLM procedure in SAS (SAS Institute Inc., 2000) were used to test the differences in analysed traits (body measurements, biochemical parameters, and consumption) due to different feeding groups (C, E1, E2, end E3). Morrill and Dayton (1973) observed that starter consummation tended to increase when 10 % of whey was included. They also noticed that the highest inclusion of whey in calf starter depressed consumption. Feng et al. (2007) presented results regarding the influence of fermented soybean meal in comparison to soybean meal on the growth of piglets. They found that fermented soybean meal had a positive influence on piglet's growth, due to reduced ANFs and the greater concentrations of essential amino acids (AA) Following these findings, the influence of soy proteins with low ANFs was investigated on calves in this study. Statistical analyses showed that the experimental treatments did not differ (P>0.05) in body traits of calves at first measurement ( Table 4). The withers height at the second measurement was highest (P<0.05) for the animals in the E1 group. Furthermore, a statistically significant differences (P<0.05) in wither heights were determined between animals in the E2 group and the E1 and  Starter with added d whey powder and soy proteins with low ANFs + lysine and methionine In order to get a good insight into the metabolic and health status of certain animals, it is very useful to use the haematological and biochemical parameters of blood analysis. The values of different blood parameters in calves depend on age, due to colostrum intake at the beginning of life and transition from liquid to dry diet, in the pre-weaning and weaning period. Furthermore, in growing calves, the feeding and the rearing system had an important effect on the values of different blood parameters (Klinkon and Ježek, 2012). The effect of feeding becomes even more apparent after the fifth week of age when the consummation of dry food (hay, starter) increases.

Results and discussion
From all biochemical parameters, the significant (P<0.05) differences were found only for NEFA in the second measurement, all experimental groups differentiated from control (Table 5). NEFA value was lower in the experimental group compared to the control group (0.08; 0.10; 0.09: 0.19), which is a sign that energy is not obtained from adipose tissue. The values of GGT in I. measurement (about 7th week of calves age) suggest that calves were healthy according to Ježek (2007), but in the measurement II. (about 12 th week of calves age) values were slightly higher. Bouda and Jagoš (1984) noted that the reference value for GGT in plasma of calves with 2 months of age is 40.8 ± 15.6 U/L and for calves 3 months of age is 31.8 ± 6.6 U/L. The increased plasma level of GGT is usually associated with liver damage (Ježek, 2007), but in our research, the level of GGT was into reference value. When comparing results from this research with results of Ježek (2007), the values of urea, calcium, and phosphorus were similar, Table 4. Least-squares means (LSMs) of body measurements of calves from different feeding groups at 50 (I. measurement) and 91 (II. measurement) day of age The consumption of milk replacer (as is in grams and litres, and on DM basis in grams) were statistically different (P<0.0001) between animals from E1 and E3 groups and those in groups C and E2 (Table 6). Regarding the consumption of starter (as is and on DM basis) and total consumption DM (g), animals in the control group consumed less in comparison to animals in experimental groups (E1, E2, E3). Furthermore, animals from the groups E1 and E2 had a lower starter consumption compared to animals in group E3 (P<0.0001). Stamey et al. (2012) concluded that calves should consume at least 1 kg of starter DM daily before weaning in order to ensure continued post-weaning growth. They found out that a starter with 25.5 % of crude protein provides the best starter intake (particularly around weaning) and growth for dairy calves, compared to a conventional starter with 19.6 % of crude protein. Holstein calves in the research of Mirghaffari et al. (2012) ate between 731 and 945 grams of the total dry matter, depending on the different group in the starter differentiated in the form of wheat, but slightly lower compared to the results of this research. Stamey et al. (2012) determined a higher dry matter intake of milk replacer and starter with crude proteins in comparison to the conventional starter in Holstein calves, and comparable with this research. Their calves had a higher intake of milk replacer but lower of the starter. Higher starter intake results in faster rumen development. Greater body weight, daily gain, glucose, albumin, and BHBA concentrations and higher insulin activity seem to be the results of a better rumen development in calves from experimental groups.