Effect of oat hay provision method on growth performance,rumen fermentation and blood metabolites of dairy calves during preweaning and postweaning periods

The comparison of the effects of all forage offering methods would be particularly useful information in modeling growth performance and rumen fermentation of dairy calves. Therefore, this study attempted to evaluate the effects of methods of oat hay provision on growth performance, rumen fermentation and biochemical blood indices of dairy calves during preweaning and postweaning periods. At birth, 40 female Polish Holstein-Friesian calves (3 days of age; 39.6 ± 0.39 kg BW) were randomly assigned to four treatment groups differing in the access to chopped oat hay: CON (control, starter without oat hay), OH (starter feed containing 10% DM basis oat hay), OH-FC (starter feed containing 10% DM basis oat hay and oat hay fed as free-choice provision in different buckets) and FC (starter feed and oat hay fed as free-choice provision in different buckets). The calves were weaned on day 56, and then the study continued until day 84. Intakes of starter feed and oat hay were recorded daily, whereas BW and hip height (HH) on day 3 and then every 14 days. Samples of blood were collected on the initiation of experiment and then every 14 days, and rumen contents on day 28, 56 and 84. No treatment effects were found for starter, starch, CP, total DM intake, average daily gain, feeding efficiency, change in HH, ruminal fluid pH, concentrations of ruminal propionate and NH₃-N, concentrations of urea nitrogen and non-esterified fatty acids in the blood. There were differences between treatments in terms of ruminal total volatile fatty acids and molar concentrations of acetate, butyrate and acetate to propionate ratio; highest in OH and OH-FC groups, especially during the postweaning period. On the other hand, lower concentrations of iso-valerate were found in OH and OH-FC groups on day 56 and 84. The concentrations of IGF-I throughout the experiment and β-hydroxybutyrate during the postweaning period in the blood were influenced by treatment, with the greatest values observed in OH and OH-FC calves. Results of this study indicate that starter feed containing chopped oat hay improves rumen fermentation parameters, which might allow successful transition from preruminant to mature ruminant state. Also, providing chopped oat hay with pelleted starter feed seems to be a better method than free-choice supplementation.     

Determining optimum age of Holstein dairy calves when adding chopped alfalfa hay to meal starter diets based on measures of growth and performance

The present study was conducted to determine the optimum age of Holstein dairy calves for an effective inclusion of alfalfa hay (AH) in starter feed on performance, apparent digestibility and feeding behavior. A total of 40 Holstein dairy calves (20 female and 20 male) were used in a completely randomized design in which calves were randomly assigned to one of four different dietary treatments including control (CON) calves fed starter feed without any forage and three treatments consisting of the same starter feed plus 15% chopped AH fed when calves were at the 2^nd (AH2), 4^th (AH4) or 6^th (AH6) week of age. Calves were individually housed and bedded with sand that was replaced every other day. Feed and water were available ad libitum throughout the experiment. Calves were fed milk at 10% of birth BW twice daily until d 57. The study concluded when calves were 73 days old. Starter intake was recorded daily and BW was measured weekly. Data were analyzed as a complete randomized design by MIXED procedures of SAS. Results demonstrate that calves receiving AH treatments numerically consumed more starter feed (0.62 v. 0.78, 0.71 and 0.65 kg/day for CON, AH2, AH4 and AH6, respectively) and had greater average daily gain (ADG) compared with CON (0.48 v. 0.57, 0.49 and 0.49 kg/day for CON, AH2, AH4 and AH6), although the significant difference was observed only between AH2 and CON. Among AH treatments, calves in AH2 had better performance than AH6 in several cases including starter intake, ADG. No detectable differences were observed, however, in apparent dry matter, organic matter or CP digestibility among treatments. Ruminal pH and NH₃ concentrations, measured on weeks 4, 6, 8 and 10, were lower for calves fed CON compared with other treatments, with ammonia concentrations decreasing over time. Calves in the AH treatments spent more time eating and ruminating compared with CON. Calves fed CON, however, spent more time on laying down compared with other treatments. Overall, results from the present study illustrated that inclusion of alfalfa in starter feed for calves at 2 weeks of age may improve feed intake, ADG and stimulate rumination in young Holstein dairy calves. Results, however, should be viewed with caution as the number of calves per treatment was small and large calf-to-calf variation may have affected the results reported.     

Effects of supplemental fat sources and forage feeding levels on growth performance,nutrient digestibility,ruminal fermentation,and nitrogen utilization in dairy calves

Knowledge regarding the potential interactions between supplemental fat source and fiber level in starter diet of dairy calves is lacking. The aim of the present study was to investigate the effects of supplemental saturated fat [palm fat (PLF) containing 86% palmitic acid (C16:0)] vs. unsaturated fat [soybean oil (SBO) containing 51% linoleic acid (C18:2)] and forage level on feed intake, growth performance, ruminal fermentation, nutrient digestibility, and metabolic traits in dairy calves. Forty newborn Holstein female calves (BW = 39.7 ± 1.8 kg) were assigned to 1 of 4 treatment groups (each consisting of 10 animals) in a 2 × 2 factorial arrangement of fat source [soybean oil vs. palm fat; 3% of starter based on DM basis] and alfalfa hay level (0 vs. 15%, on DM basis): SBO or PLF with (AH) or without (NAH) alfalfa hay. Calves had ad libitum access to water and starters throughout the study and a constant amount of milk was offered among experimental calves during the pre-weaning period. All calves were weaned on day 63 of age and remained in the study until day 73 of age. The results showed that the lowest and the highest starter intake and average daily gain during pre-weaning period was observed when calves received SBO-AH and PLF-AH, respectively. Accordingly, the lowest wither and hip heights at weaning time (day 63) and final wither height (day 73) were observed in SBO-AH group across treatments. Calves received PLF-AH had the highest weaning and final BW compared to other groups. Feed efficiency tended to be higher in PLF groups compared with SBO calves. Calves fed SBO-AH had the lowest digestibility of organic matter and neutral detergent fiber and also total short chain fatty acid concentrations in rumen compared with other groups. The SBO calves had lower urinary allantoin, urinary purine derivatives, and microbial protein synthesis than PLF calves; however, urinary nitrogen increased with SBO supplementation. In summary, the supplementation of SBO rich in C18:2 and AH during the pre-weaning period resulted in negative responses on growth performance, digestibility, and ruminal fermentation profile. Therefore, the inclusion SBO rich in C18:2 along with forage in the starter is not recommendable for young dairy calves.     

Effect of alfalfa hay and starter feed supplementation on caecal microbiota and fermentation,growth, and health of yak calves

The caecum is the primary site where microbial fermentation and acidosis occurred. The supplementation of starter feed and alfalfa hay has the potential to influence caecal microbiota and then affect caecal fermentation. This study aims to investigate the effect of starter feed and alfalfa hay supplementation on caecal microbiota, immune homeostasis, and growth of preweaning yaks. Twenty 30-day-old male yak calves were randomly assigned to four groups, which separately fed with milk replacer (CON group), milk replacer with alfalfa hay (A group), milk replacer with starter feed (S group), and milk replacer with starter feed plus alfalfa hay (SA group) throughout the trial. Growth performance and plasma physiological and biochemical indicators were measured every 30 days. Calves were sacrificed at 120 days of age. The caecal contents were collected for measuring pH and contents of volatile fatty acids (VFAs) and lipopolysaccharide (LPS) and for characterizing caecal microbiota. The results indicated that individual or simultaneous supplementation with alfalfa hay and starter feed all significantly increased the BW, body height, body length, and chest girth of yak calves. However, supplementation with starter feed significantly increased plasma cortisol, nitric oxide, tumor necrosis factor-α, and interferon-γ concentrations and the ratio of aspartate aminotransferase to alanine aminotransferase of yak calves when compared with the control and alfalfa hay feeding groups, while the co-supplementation of starter feed and alfalfa hay could significantly decrease these inflammation-related indices when compared with the starter feeding group. Sequencing of the 16S rRNA gene showed that starter feed and alfalfa hay separately stimulated the proliferation of starch-decomposing and cellulose- or hemicellulose-decomposing bacteria. This also significantly increased the levels of acetate, propionate, butyrate, valerate, isobutyrate, and isovalerate in the caecal contents. Furthermore, compared with the S and CON groups, the significantly increased genera of Desulfobulbus, Olsenella, Pseudoflavonifractor, and Stomatobaculum in the SA and A groups were beneficial to the immune homeostasis, and the significantly decreased Blautia, Clostridium IV, Bacteroides, Eubacterium, Clostridium XVIII, and Mogibacterium in the SA and A groups were related to the reduced caecal lactate and LPS contents, the decreased inflammatory reaction, and the improved healthy hepatic condition of yak calves. In conclusion, milk replacer supplemented with alfalfa hay and starter feed is recommended during preweaning to improve yak calf health and growth because this regimen promotes the growth and maintains the immune homeostasis of yak calves.     

Effects of Dietary Linseed Oil and Propionate Precursors on Ruminal Microbial Community,Composition, and Diversity in Yanbian Yellow Cattle

The rumen microbial ecosystem is a complex system where rumen fermentation processes involve interactions among microorganisms. There are important relationships between diet and the ruminal bacterial composition. Thus, we investigated the ruminal fermentation characteristics and compared ruminal bacterial communities using tag amplicon pyrosequencing analysis in Yanbian yellow steers, which were fed linseed oil (LO) and propionate precursors. We used eight ruminally cannulated Yanbian yellow steers (510 ± 5.8 kg) in a replicated 4 × 4 Latin square design with four dietary treatments. Steers were fed a basal diet that comprised 80% concentrate and 20% rice straw (DM basis, CON). The CON diet was supplemented with LO at 4%. The LO diet was also supplemented with 2% dl-malate or 2% fumarate as ruminal precursors of propionate. Dietary supplementation with LO and propionate precursors increased ruminal pH, total volatile fatty acid concentrations, and the molar proportion of propionate. The most abundant bacterial operational taxonomic units in the rumen were related to dietary treatments. Bacteroidetes dominated the ruminal bacterial community and the genus Prevotella was highly represented when steers were fed LO plus propionate precursors. However, with the CON and LO diet plus malate or fumarate, Firmicutes was the most abundant phylum and the genus Ruminococcus was predominant. In summary, supplementing the diets of ruminants with a moderate level of LO plus propionate precursors modified the ruminal fermentation pattern. The most positive responses to LO and propionate precursors supplementation were in the phyla Bacteriodetes and Firmicutes, and in the genus Ruminococcus and Prevotella. Thus, diets containing LO plus malate or fumarate have significant effects on the composition of the rumen microbial community.     

Effects of different sources of nitrogen on performance,relative population of rumen microorganisms,ruminal fermentation and blood parameters in male feedlotting lambs

Slow-release urea (SRU) can substitute dietary protein sources in the diet of feedlotting ruminant species. However, different SRU structures show varying results of productive performance. This study was conducted to investigate the effect of different sources of nitrogen on performance, blood parameter, ruminal fermentation and relative population of rumen microorganisms in male Mehraban lambs. Thirty-five male lambs with an average initial BW of 34.7 ± 1.8 kg were assigned randomly to five treatments. Diets consisted of concentrate mixture and mineral and vitamin supplements plus (1) alfalfa and soybean meal, (2) wheat straw and soybean meal, (3) wheat straw and urea, (4) wheat straw and Optigen® (a commercial SRU supplement) and (5) wheat straw and SRU produced in the laboratory. No statistical difference was observed in animal performance and DM intake among treatments. The mean value of ruminal pH and ammonia was higher (P < 0.05) for the SRU diet compared with WU diet. The difference in pH is likely to be due to the higher ammonia level as VFAs concentrations were unchanged. The level of blood urea nitrogen (BUN) was different among treatments (P = 0.065). The highest concentration of BUN was recorded in Optigen diet (183.1 mg/l), whereas the lowest value was recorded in wheat straw-soybean meal diet (147 mg/l). The amount of albumin and total protein was not affected by the treatments. The relative population of total protozoa, Fibrobacter succinogenes, Ruminococcus flavefaciens and Ruminococcus albus in the SRU treatment was higher (P < 0.01) than that in urea treatment at 3 h post-feeding. During the period of lack of high-quality forage and in order to reduce dietary costs, low-quality forage with urea sources can be used in the diet. Results of microbial populations revealed that SRU can be used as a nitrogen source which can sustainably provide nitrogen for rumen microorganism without negative effects on the performance of feedlotting lambs.     

Reciprocal combinations of alfalfa hay and corn silage in the starter diets of Holstein dairy calves: effects on growth performance,nutrient digestibility,rumen fermentation and selected blood metabolites

Adding corn silage (CS) instead of alfalfa hay (AH) to the finely ground starter diet would improve calf performance if feed intake or feed efficiency is increased. We investigated the effects of replacing AH with CS in the starter diet on nutrient intake, digestibility, growth performance, rumen fermentation and selected blood metabolites in Holstein calves. Newborn male calves (n = 30; 3 days of age; 40.2 ± 1.28 kg BW) were assigned randomly to three groups receiving starter diets containing chopped AH (10% dry matter (DM) basis; AH diet), CS (10% DM, CS diet) or their combination (each at 5% level; AHCS diet). The starter diets had the same nutrient composition but differed in DM content (91.2%, 87.5% and 83.8% for AH, AHCS and CS, respectively). The calves were weaned on day 50, and the study continued until day 70. Nutrient intake, BW (at weaning and at the end of the study) and body measurements were not affected by the diet. During the post-weaning period, average daily gain tended to be greater on CS than on AH diet. Feed efficiency was greater in CS than in AH or AHCS calves during the post-weaning period. Digestibility of neutral detergent fiber was greater in AHCS and CS compared with AH during the post-weaning period. Concentration and profile of volatile fatty acids and ruminal fluid pH were not affected by the diet. Replacing AH with CS in the starter diet had no effect on feed intake, growth performance and general health of the calves. These results indicate that AH and CS can be used interchangeably in dairy calf starter diets until 70 days of age, allowing dairy producers more choices in selecting the feed ingredients.     

Effects of hydrolyzed yeast supplementation in calf starter on immune responses to vaccine challenge in neonatal calves

The effects of hydrolyzed yeast supplementation on growth performance, health and immune-physiological parameters in neonatal calves challenged with vaccine were investigated. Twelve Holstein calves were started in the experiment at 2 ± 1 days of age and were studied for 35 days. Calves were randomly assigned to each of two dietary treatments, a control (CON) and hydrolyzed yeast (HY) group. The calves in the HY group received control calf starter supplemented with 0.2% HY. All calves were given calf starter ad libitum for 5 weeks starting in week 1. Calves were also given whole milk according to a step-down milking protocol. In order to induce immune responses, all calves were challenged with Hog cholera and Erysipelothrix insidiossa live vaccines by intramuscular injection at 3 weeks of age. Growth performance and feed intake were not affected by dietary treatment throughout the experimental period, except that the HY group had significantly higher (P < 0.05) milk intake than did the CON group at 3 weeks of age. Calves in the HY group showed significantly better (P < 0.05) fecal and health scores at 3 weeks compared to those in the control group. After vaccine challenge, neutropenia, lymphophilia and thrombocytopenia were observed in the CON group, but calves in the HY group did not show significant changes of leukocytes. The average concentration of serum haptoglobin in the HY group was significantly higher (P < 0.05) at 1 and 3 days post-vaccine challenge (DPVC) than that of CON group. Feeding HY supplemented calf starter resulted in a higher (P < 0.05) relative amount of bacterial and viral - specific IgA than in the CON group at 5 DPVC. Although the percentage of CD4+ T cells was significantly (P < 0.05) higher in the HY group than in the CON group at -2 DPVC, significant differences between groups after vaccine challenge was not observed during the experimental period. These results suggest that 0.2% HY supplementation in calf starter can improve the health status and immune-related serum protein production and affect blood cell composition in neonatal calves after vaccine challenge.     

Influence of spray-dried rumen fluid supplementation on performance,blood metabolites and cytokines in suckling Holstein calves

Rumen fluid from slaughtered animals is one of the wastes of slaughterhouses released to the environment that, due to its high nitrogen and phosphorus contents, can lead to soil and groundwater pollution. Meanwhile, it contains ruminal microbes and some bioactive compounds such as enzymes, minerals, vitamins and organic acids. This study was designed to examine the potential of rumen fluid as a feed additive. Therefore, the effects of spray-dried rumen fluid (SDR) with 1% maltodextrin on the performance, blood metabolites and some cytokines of sucking dairy calves during the pre-weaning phase were investigated. Forty male Holstein calves, with a mean weight of 39.4 ± 3.7 kg and 7 ± 1 days old, were randomly assigned to four groups (n = 10 calves per group) in a completely randomized design. Experimental treatments were: control diet with no additive (CON); control diet with 0.5 g/day of SDR (SDR0.5); control diet with 1 g/day of SDR (SDR1); and control diet with 1.5 g/day of SDR (SDR1.5). Daily feed intake and average daily gain of calves were not affected by feeding SDR as a feed additive. Cholesterol concentration was significantly affected by the 20th and 40th days of the experiment and decreased linearly by increasing SDR feeding level. Levels of liver enzymes, including aspartate aminotransferase and alanine aminotransferase, in the blood decreased by feeding SDR at day 40 of the experiment. Serum concentration of interleukin-6 at day 20 was not affected by dried rumen fluid feeding, whereas at day 40, a significant effect was observed among experimental treatments. The lowest value was recorded for SDR1.5 v. control calves. At day 20, the serum concentration of interferon-γ was influenced by supplementing SDR, and the highest value was recorded for SDR1.5 calves. The inclusion of SDR with 1% maltodextrin in suckling dairy calves had beneficial effects on the stimulation of calves’ immune system.     

Partial replacement of triticale for corn grain in starter diet and its effects on performance,structural growth and blood metabolites of Holstein calves

The primary objective of this study was to examine the effects of different inclusion rates of dietary triticale replacing corn grain in starter rations of dairy calves on feed intake, average daily gain (ADG), feed efficiency, skeletal growth, fecal score, and selected blood and ruminal parameters. In all, 30 4-day-old Holstein calves (15 female and 15 male) were blocked by gender and birth weight, and then randomly allotted to three treatment groups (n=10 calves/treatment) and received either a corn-based diet without triticale (T0), or a diet containing 16% (T16) or 32% (T32) triticale (25% and 50% corn replaced by triticale, respectively) for 10 weeks. Calves were weaned on day 43 of study and remained on the study until day 70. During post-weaning period, calves fed T32 had the lowest starter intake (1.78 kg/day; P=0.02). In contrast, ADG was not affected in pre-weaning and overall periods, but calves fed T32 had a lower ADG (P=0.04) as compared with calves fed T0 in post-weaning period. No dietary effect was detected for feed efficiency. Dietary treatment did not affect heart girth and body length; however, height at wither and hip at weaning increased in calves fed triticale compared with T0. No detectable effects were observed in serum glucose and β-hydroxybutyrate. No difference was detected in blood urea nitrogen on day 35 either but on day 50 and day 70 the greatest concentration was recorded for calves fed T16. Compared with the control, ruminal ammonia concentration was increased for calves fed T32 (4.34 v. 7.50 mmol/l) and T16 (4.01 v. 8.12 mmol/l) on day 35 and day 50. No difference was detected in ruminal pH on day 35 or day 50; however, calves fed T32 had the lowest pH (6.11) at 70 days. No significant effect was detected in days scoured, respiratory score and general appearance. Under our experimental conditions, it appears that triticale at 16% dry matter (i.e. replacing corn grain up to 25%) in the starter diet does not have adverse effects on the performance and intake of calves. Therefore, substituting corn partially with triticale in calf starter diets may prove beneficial in places where corn is less abundant or its price is prohibitive. The low number of calves per treatment however may have limited the statistical power to detect significant differences among treatments, possibly affecting the results, which should be interpreted with caution.     

Grain source and chromium supplementation: effects on feed intake,meal and rumination patterns,and growth performance in Holstein dairy calves

Carbohydrate-rich diets may increase urinary excretion of chromium (Cr) and increase its requirements. This study was conducted to investigate the effect of grain type (barley v. corn) and Cr supplementation on feed intake, feeding behavior and weight gain in dairy calves. Forty-eight neonatal Holstein female calves were assigned randomly to four experimental diets in a 2×2 factorial arrangement. Experimental diets were either barley-based diet (BBD) or corn-based diet (CBD) supplemented with (+Cr) or without (−Cr) Cr as Cr-methionine (0.05 mg/kg of BW^0.75). Chromium was provided in milk (from days 3 to 73 of life) during the pre-weaning period and then in pre-warmed water (from day 74 until day 94 of life) after weaning. Meal length tended to increase in calves fed the BBD v. CBD during the pre-weaning period. During the post-weaning period, meal size, inter-meal interval, and eating rate increased concurrently but meal frequency and eating time decreased in the BBD v. CBD. During the pre-weaning period, feed efficiency, BW at weaning, and heart girth increased and non-nutritive oral behaviors tended to decrease with Cr supplementation. Due to increased meal frequency, the starter feed intake but not eating time increased by Cr supplementation during the post-weaning period. Supplementing Cr increased starter feed intake, final BW, average daily gain and heart girth during the overall period. Rumination time increased in BBD+Cr calves due to increases in the frequency and duration of rumination, or decreased rumination bout interval. Overall, the type of grain had no effect on feed intake and growth performance; however, Cr supplementation decreased non-nutritive oral behaviors and increased starter feed intake via increasing the meal frequency and thereby improved growth performance.     

Effects of physical forms of starter feed on growth,nutrient digestibility,gastrointestinal enzyme activity,and morphology of pre- and post-weaning lambs

The physical form of starter feed may affect the gastrointestinal development and the performance of ruminant. However, little information is available on how changes in the physical forms of starter feed influence the performance of lambs, especially during the pre- and post-weaning periods. The aim of this study was to investigate the effects of different physical forms of starter feeds on growth performance, nutrient digestibility, gastrointestinal enzyme activity, and morphology of pre- and post-weaning lambs. Twenty-four 8-day-old male Hu lamb (5.04 ± 0.75 kg BW) were randomly assigned to one of two dietary treatments: 1) a pelleted starter (PS) feed and 2) a textured starter (TS) feed, which included coarse mashed steam-flaked corn. From eight to thirty-five days of age (pre-weaning), the lambs were bottle-fed milk replacer (MR) at 2% of BW measured on day 8. All lambs were weaned at day 35 when feeding of MR was stopped. Six lambs for each treatment were euthanized at 21 or 42 days of age for sampling. The following results are obtained by variance analysis: TS lambs had a greater (P < 0.05) final BW, higher apparent digestibility of starch and ether extract, activities of α-amylase pre- or post-weaning, and higher (P < 0.05) average dry matter intake and lipase post-weaning in small intestine contents and had a trend of significantly higher average daily gain post-weaning (P = 0.07). Rumen development analysis of TS lambs showed a significantly higher (P < 0.05) relative weight of rumen post-weaning, greater papillae length, increased circular and layered muscle, increased sectional area pre- and post-weaning, and increased rumen papillae width post-weaning. Textured starter treatment increased the villus height and villus width (except jejunum pre-weaning) of the whole small intestine and villus height to crypt depth ratio of jejunum and ileum during the whole period and tended to increase the relative weight of the rumen pre-weaning (P = 0.07). The results indicated that TS feeding is more beneficial to lambs over the weaning transition than PS in promoting gastrointestinal development, intestinal enzyme activities, nutrient digestibility, and growth performance. The findings provide new insights into the selection of physical forms of starter feeds in lamb production. Further research with more animals and female lambs is needed to obtain a more complete conclusion.     

Effect of cold process monensin enriched urea molasses mineral blocks on performance of crossbred calves fed a wheat straw based diet

Twenty male crossbred calves were divided into four equal groups. Calves in groups I and II were fed wheat straw ad libitum with a concentrate mixture with or without monensin (30 mg per day per animal). Calves in groups III and IV were fed wheat straw ad libitum with 70% of the allocated concentrate mixture and had free access to urea molasses mineral block (UMMB) with or without monensin (100 ppm). Wheat straw intake was higher (P<0.05) in UMMB supplemented groups, but total dry matter (DM) and crude protein (CP) intake did not differ. ME (Mcal per day) intake was higher (P<0.05) in UMMB supplemented groups. Digestibility of DM, OM, EE, and NDF did not differ due to UMMB or monensin supplementation, although ADF digestibility was increased (P<0.01) with UMMB supplementation. Although the N balance was similar among the groups, the Ca and P balances were higher in UMMB supplemented groups. Blood glucose level was increased (P<0.05) due to monensin treatment but plasma urea N level did not differ. Average body weight gain, feed conversion efficiency, protein utilisation efficiency, and energy utilisation efficiency were higher (P>0.05) in monensin treated groups without any change in body composition. Replacing 30% of a concentrate mixture with a cold process UMMB increased the proportional contribution of wheat straw to DM intake but had no effect on animal performance. However, supplementation with monensin increased the blood glucose level, protein and energy deposition, as well as body weight gain and feed efficiency, but with no change in the wheat straw and total DM consumption.     

Does adding water to a dry starter diet improve calf performance during winter?

Very recently, we added water to a dry texturized starter diet and found substantial improvements in calf performance during summer, leading to the hypothesis that the wet starter diet would also benefit calf performance during winter. Forty-five 3-day-old male Holstein calves (BW 43.4±3.4 kg) were blocked by initial BW and distributed randomly to one of three starter diets (1 calf per pen; 15 pens per treatment) that differed only in moisture content as 90%, 75% and 50% dry matter (DM; DM90, DM75 and DM50, respectively). The starter diet comprised 55.1% ground ingredients (soybean meal, barley and corn gluten meal), 21.9% whole corn, 10% rolled barley and 10% chopped alfalfa hay. The mean ambient temperature averaged 2.1±0.9°C during the 70-day experiment. Calves were weaned at day 50 of the study. Although starter feed intake remained unaffected by treatment, the calves receiving DM75 and DM50 consumed more starter feed (DM basis) than those receiving DM90 diet during the first 20 days of the experiment. Body weight at weaning exhibited a quadratic response with the heaviest weaning weight (76.8 kg) occurring when calves consumed DM75 diet. Adding water to the dry starter diet tended to linearly increase final BW. Average daily gain during the pre- (0.67 kg/day) and post-weaning (1.22 kg/day) periods was the greatest for calves receiving DM75 and DM50, respectively. Although feed efficiency during the pre-weaning and overall periods did not differ across the treatments, a quadratic effect was detected in the post-weaning feed efficiency, with the lowest value being observed with DM75 diet. No difference was noted on skeletal growth parameters measured on days 50 and 70. Adding water to the dry starter diet linearly increased total volatile fatty acids concentration in the rumen. No difference among treatments existed in calf behavior recorded on days 35 and 70. As moisture content of the starter diet increased, the extent of sorting for long particles (>2 mm) and against fine particles (<0.125 mm) decreased. During the 70-day winter trial, adding water to the dry texturized starter diet with 10% chopped alfalfa hay resulted in a higher feed intake during the first weeks of life, a quadratic tendency toward improved growth rate during the pre-weaning period, and possibly a more functional rumen fermentation. A wet starter diet with 75% DM in the physical form offered in this study can be recommended to improve calf performance during winter.     

Effects of feed withdrawal duration on animal behaviour,rumen microbiota and blood chemistry in feedlot cattle: implications for rumen acidosis

Feed withdrawal (FW) is a frequent issue in open outdoor feedlot systems, where unexpected circumstances can limit the animals’ access to food. The relationship among fasting period, animal behaviour during feed reintroduction (FR) and acidosis occurrence has not been completely elucidated. Twenty steers fitted with rumen catheters were fed a high-concentrate diet (concentrate : forage ratio 85 : 15) and were challenged by a protocol of FW followed by FR. The animals were randomly assigned to one of the four treatments: FW for 12 h (T12), 24 h (T24), 36 h (T36) or no FW (control group) followed by FR. The steers’ behaviour, ruminal chemistry, structure of the ruminal microbial community, blood enzymes and metabolites and ruminal acidosis status were assessed. Animal behaviour was affected by the FW–FR challenge ( P < 0.05). Steers from the T12, T24 and T36 treatments showed a higher ingestion rate and a lower frequency of rumination. Although all animals were suspected to have sub-acute ruminal acidosis (SARA) prior to treatment, a severe case of transient SARA arose after FR in the T12, T24 and T36 groups. The ruminal pH remained below the threshold adopted for SARA diagnosis ( pH value = 5.6) for more than three consecutive hours (24, 7 and 19 h in the T12, T24 and T36 treatments, respectively). The FW–FR challenge did not induce clinical acute ruminal acidosis even though steers from the T36 treatment presented ruminal pH values that were consistent with this metabolic disorder (pH threshold for acute acidosis = 5.2). Total mixed ration reintroduction after the withdrawal period reactivated ruminal fermentation as reflected by changes in the fermentation end-products. Ruminal lactic acid accumulation in steers from the T24 and T36 treatments probably led to the reduction of pH in these groups. Both the FW and the FR phases may have altered the structure of the ruminal microbiota community. Whereas fibrolytic bacterial groups decreased relative abundance in the restricted animals, both lactic acid producer and utiliser bacterial groups increased ( P < 0.05). The results demonstrated a synchronisation between Streptococcus (lactate producer) and Megasphaera (lactate utiliser), as the relative abundance of both groups increased, suggesting that bacterial resilience may be central for preventing the onset of metabolic disturbances such as ruminal acidosis. A long-FW period (36 h) produced rumen pH reductions well below and lactic acid concentration increased well above the accepted thresholds for acute acidosis without any perceptible clinical signs.     

Influence of barley grain particle size and treatment with citric acid on digestibility,ruminal fermentation and microbial protein synthesis in Holstein calves

Chemical and physical treatments of barley grain increase ruminally resistant starch and can improve the rumen fermentation pattern. The objective of the present study was to evaluate the effects of chemical (addition of citric acid, CA) and physical (grinding to two different particle sizes, PS) treatment of barley grain on performance, rumen fermentation, microbial protein yield in the rumen and selected blood metabolites in growing calves. In all, 28 male Holstein calves (172±5.1 kg initial BW) were used in a complete randomised design with a factorial arrangement of 2 barley grain particle sizes×2 levels of citric acid. The diets were as follows: (i) small PS (average 1200 µm) barley grain soaked in water (no CA addition); (ii) small PS barley grain soaked in a CA solution (adding 20 g CA/kg barley); (iii) large PS (average 2400 µm) barley grain soaked in water (no citric acid addition) and (iv) large PS barley grain soaked in a citric acid solution (adding 20 g CA/kg barley). Barley grain was then incorporated at 35% in a total mixed ration and fed to the calves for 11 weeks. Feeding small PS barley decreased feed intake (P=0.02) and average daily weight gain (P=0.01). The addition of CA to barley grain did not affect intake but increased weight gain (P<0.01) and improved feed to gain ratio (P=0.03). Digestibility of organic matter and NDF tended (P<0.10) to increase, whereas faecal scoring was improved (P=0.03) and the presence of undigested grain particles in faeces was reduced (P<0.01) with CA-treated barley grain. Glucose and urea concentrations were increased (P<0.01) in the blood of calves fed the CA-treated barley grain. Ruminal pH tended (P=0.08) to be decreased with more finely ground barley and was increased when barley grain was treated with CA. Total volatile fatty acid concentrations in the rumen did not differ among treatments (P>0.05). However, the molar proportion of propionate was increased (P=0.03) when barley was more finely ground, and that of acetate was increased (P=0.04) when CA was added to barley grain. The ruminal concentration of ammonia nitrogen was increased (P<0.01) and microbial nitrogen synthesis in the rumen tended to decrease by adding CA to barley. Treating barley grain with citric acid increased fibre digestibility of total mixed rations, attenuated the decrease in ruminal pH, and improved weight gain and feed efficiency in male Holstein growing calves fed a high-cereal diet (550 g cereal grain/kg diet).     

Performance and tissue fatty acid profiles in veal calves fed diets supplemented with conjugated linoleic acids

Three groups of six calves each were fed a milk replacer at 0.8 kg and a starter concentrate ad libitum. Calves of the control group received the basal diet supplemented with rapeseed oil at 10 g per kg of feed solids. Calves of treatment groups were fed diets supplemented with a synthetically produced oil containing 62.3% methyl esters of CLA. The CLA-oil was added to milk at expense of rapeseed oil and fed at 5 and 10 g x kg(-1) feed solids for 63 days. Calves were slaughtered at 115 days of age. There was no significant effect of CLA on growth, intake of starter, feed conversion, chemical composition of meat and its oxidative stability. Dietary supplementation with CLA at 10 g x kg(-1) significantly increased CLA content in m. longissimus dorsi (MLD) from 5.6 to 19.3 mg x 100 g(-1), in liver from 13.1 to 68.8 mg x 100 g(-1), and in perirenal fat from 0.37 to 3.17 g x 100 g(-1). Dietary CLA decreased the ratio of cis-9, trans-11 and trans-10, cis-12 isomers of CLA in tissues, concentration of monounsaturated fatty acids in the MLD and fat, as well as the concentration of fatty acids with 20 and 22 carbon atoms. It can be concluded that in veal calves unprotected CLA apparently escaped ruminal hydrogenation, but was preferentially incorporated into depot fat.     

Effect of wheat dried distillers grains and enzyme supplementation on growth rates,feed conversion ratio and beef fatty acid profile in feedlot steers

The objectives of this study were to determine: (1) the effect of wheat dried distillers grain with solubles (DDGS) inclusion, and (2) dietary feed enzyme (FE; Econase XT) supplementation in a finishing diet containing wheat DDGS on fatty acid profile of the pars costalis diaphragmatis muscle of beef cattle. A total of 160 crossbred yearling steers with initial BW of 495±38 kg were blocked by BW and randomized into 16 pens (10 head/pen). The pens were randomly assigned to one of the four treatments: (1) control (CON; 10% barley silage and 90% barley grain-based concentrate, dry matter (DM) basis); (2) diet containing 30% wheat DDGS in place of barley grain without FE (WDG); (3) WDG diet supplemented with low FE (WDGL; 1 ml FE/kg DM); and (4) WDG diet supplemented with high FE (2 ml FE/kg DM). The pars costalis diaphragmatis muscle samples were collected from cattle at slaughter at the end of the finishing period (120 days) with a targeted live weight of 650 kg. No differences in organic matter intake, final BW and average daily gain were observed among treatments. However, steers fed WDG had greater (P<0.01) feed conversion ratio than those fed CON, and increasing FE application in wheat DDGS-based diets tended (P<0.10) to linearly decrease feed conversion ratio. In assessing the effects of including WDG diets without FE, concentration of total polyunsaturated fatty acids (PUFA) in muscle tended to be greater (P<0.10) for steers fed WDG than steers fed CON. In addition, inclusion of wheat DDGS into the diet increased (P<0.05) concentration of CLA and vaccenic acid (VA) in muscle and also resulted in a higher (P<0.05) ratio of n-6/n-3 PUFA compared with that from steers fed CON diet. Increasing FE application in wheat DDGS-based diets did not modify the concentrations of individual or total fatty acids. These results suggest that inclusion of wheat DDGS in finishing diets may improve fatty acid profile of beef muscle which could benefit human health.     

Trace mineral source influences digestion,ruminal fermentation,and ruminal copper,zinc, and manganese distribution in steers fed a diet suitable for lactating dairy cows

High solubility of certain trace minerals (TM) in the rumen can alter nutrient digestibility and fermentation. The objectives of the present studies were to determine the effects of TM source on 1) nutrient digestibility and ruminal fermentation, 2) concentrations of soluble Cu, Zn, and Mn in the rumen following a pulse dose of TM, and 3) Cu, Zn, and Mn binding strength on ruminal digesta using dialysis against a chelating agent in steers fed a diet formulated to meet the requirements of a high producing dairy cow. Twelve Angus steers fitted with ruminal cannulae were adapted to a diet balanced with nutrient concentrations similar to a diet for a high producing lactating dairy cow for 21 d. Steers were then randomly assigned to dietary treatments consisting of 10 mg Cu, 40 mg Mn, and 60 mg Zn/kg DM from either sulfate (STM), hydroxychloride (HTM) or complexed trace minerals (CTM). The experimental design did not include a negative control (no supplemental Cu, Mn, or Zn) because the basal diet did not meet the National Research Council requirement for Cu and Zn. Copper, Mn, and Zn are also generally supplemented to lactating dairy cow diets at concentrations approximating those supplied in the present study. Following a 14-d adaptation period, total fecal output was collected for 5-d. Following the fecal collection period, rumen fluid was collected for Volatile fatty acid (VFA) parameters. On the following day, the same diet was provided for 14 d, without supplemental Cu, Zn, and Mn. This period served as a wash-out period. A pulse dose of 100, 400, and 600 mg of Cu, Zn, Mn, respectively, from either STM, HTM, or CTM, was administered via ruminal cannulae to the steers on day 15. Over a 24-h period ruminal samples were obtained every 2-h. Following centrifugation, the supernatant was analyzed for Cu, Mn, and Zn. Ruminal solid digesta samples from times 0, 12, and 24 h after bolus dosing were exposed to dialysis against Tris-EDTA. Digestibility of NDF and ADF were lesser in STM vs. HTM and vs. CTM supplemented steers. Steers receiving HTM and CTM had greater total VFA concentrations than STM, and molar proportions of individual VFA were not affected by treatment. Ruminal soluble Cu and Zn concentrations were greater post dosing in STM and CTM supplemented steers at 2, 4, and 6 h for Cu and 4, 6, 8, 10 and 12 h for Zn when compared to HTM supplemented steers. The release of Cu and Zn from ruminal solid digesta following dialysis against Tris-EDTA at 12 and 24 h postdosing was greater for steers receiving HTM compared to those receiving STM or CTM. Results indicate trace mineral source impacts: 1) how tightly bound Cu and Zn are to ruminal solid digesta; 2) fiber digestion; 3) and ruminal total VFA concentrations.