TECHNICAL BULLETIN 216 ISSN 0070-2315 EFFECT OF REPLACEMENT OF ALFALFA HAY BY BARLEY STRAW IN ISO-NITROGENOUS DIETS FED TO FRIESIAN COWS IN EARLY LACTATION M. Hadjipanayiotou AGRICULTURAL RESEARCH INSTITUTE MINISTRY OF AGRICULTURE, NATURAL RESOURCES AND THE ENVIRONMENT NICOSIA CYPRUS SEPTEMBER 2003
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EFFECT OF REPLACEMENT OF ALFALFA HAY BY BARLEY STRAW IN ISO-NITROGENOUS DIETS FED TO FRIESIAN COWS IN EARLY LACTATION M. Hadjipanayiotou SUMMARY Alfalfa as fresh, hay or silage is considered by most farmers as an indispensable ingredient in the total diet for maximum performance in highly producing ruminant animals. The present investigation was undertaken to study the effect of replacing alfalfa hay by barley straw on the lactation performance of cows in early lactation offered an iso-nitrogenous total ration. Forty four Friesian cows were placed on two experimental diets (Barley straw, S or Alfalfa hay, A) at 28±3 days post-partum based on their milk yield one week prior to allocation to treatments. The two roughages (3.5 kg/cow/day) were offered along with a concentrate mixture plus barley hay (3.5 kg/cow/day) to meet their maintenance and production requirements. The two experimental diets, were made iso-nitrogenous by offering one of two concentrate mixtures (17.9±1.74% to S and 21.7± 2.0% to A CP, dry matter basis). There were no differences between diets in body weight changes during the course of the trial. Similarly there were no differences between diets for initial milk yield and daily milk (P>0.05) and/or fat corrected (4%) milk yield (P>0.05) during the course of the trial. Milk fat (P<0.01) and TS (P<0.05) of cows on the S diet were greater than those on the A diet. Differences between diets for CP and ash content of milk were not significant (P>0.05). Lactation number had a significant effect on initial and final weight (P<0.01), but not on weight gain. Initial and final body weight as well as milk and FCM yield were greater with advancing lactation number. The daily roughage and concentrate allowance was completely consumed. Concentrate intake by cows on the S diet was higher (P<0.05) than that of cows on the A diet. Of the apparent digestion coefficients (DM, OM, CP) measured on four Chios wether sheep per diet, only OM digestibility reached significance. It is concluded that there is no difference in protein utilization from either soybean meal or alfalfa hay, and that similar milk yields can be produced by dairy cows fed either alfalfa hay or barley straw provided that additional protein from soybean meal is provided to the concentrate given along with straw. ΠΕΡΙΛΗΨΗ Για την ικανοποίηση των θρεπτικών αναγκών των γαλακτοφόρων αγελάδων ψηλής παραγωγικότητας απαιτούνται σιτηρέσια µεγάλης περιεκτικότητας σε πρωτεΐνη στο συµπυκνωµένο µίγµα αλλά και σανοί πολύ καλής ποιότητας. Αυτό θεωρείται ιδιαίτερα απαραίτητο στα στάδια ψηλής παραγωγής, όπως είναι η περίοδος από τη γέννα µέχρι τις 100-120 µέρες της γαλακτικής περιόδου. Η µηδική ως φρέσκο χόρτο, σιρός ή σανός θεωρείται σηµαντικό συστατικό των σιτηρεσίων σε εντατικά συστήµατα εκτροφής. Η µηδική, αποκαλούµενη βασίλισσα των χονδρειδών τροφών σε πολλά µέρη, θεωρείται άµεσα συνδεδεµένη µε την εκτροφή ζώων ψηλών αποδόσεων. Σε χώρες όµως µε χαµηλές βροχοπτώσεις θεωρείται ασύµφορη η χρήση νερού για την παραγωγή χορτοδοτικών φυτών και το διαθέσιµο νερό χρησιµοποιείται αποδοτικότερα στην παραγωγή φρούτων και λαχανικών, µε αποτέλεσµα η χρήση υπαλλακτικών πηγών χονδροειδών ζωοτροφών να θεωρείται επιβεβληµένη. Στη µελέτη αυτή χρησιµοποιήθηκαν 44 αγελάδες της Φρισλανδικής φυλής στη περίοδο 28 έως 91 µέρες της γαλακτικής περιόδου. Τα ζώα τοποθετήθηκαν στα πειραµατικά σιτηρέσια [3.5 κιλά άχυρο κριθαριού (σιτηρέσιο S) ή 3.5 κιλά σανό µηδικής (σιτηρέσιο Α) ανά ζώο/µέρα] µε βάση την γαλακτοπαραγωγή τους µία βδοµάδα πριν την τοποθέτηση τους στα πειραµατικά σιτηρέσια. Το σιτηρέσιο S γινόταν ισοπρωτεινικό µε το σιτηρέσιο Α µε την προσθήκη σόγιας στο συµπυκνωµένο µίγµα. εν υπήρξαν διαφορές µεταξύ σιτηρεσίων στις µεταβολές του ζωντανού βάρους των ζώων. Επιπρόσθετα, δεν 3
υπήρξαν διαφορές µεταξύ σιτηρεσίων στην αρχική γαλακτοπαραγωγή αλλά και τη γαλακτοπαραγωγή στη διάρκεια του πειράµατος. Οι αγελάδες του σιτηρεσίου S παρήξαν γάλα µε περισσότερο λίπος και ολικά στερεά από εκείνες που έπερναν το σιτηρέσιο Α. Αντίθετα, δεν υπήρξε διαφορά µεταξύ σιτηρεσίων στην περιεκτικότητα του γάλακτος σε πρωτεΐνη και τέφρα. Η γαλακτική περίοδος επέδρασε στο αρχικό και τελικό βάρος αλλά και στη γαλακτοπαραγωγή. Γενικά, παρατηρήθηκε αύξηση της παραγωγής σε ζώα µεγαλύτερης γαλακτικής περιόδου. Σε κανένα από τα δύο σιτηρέσια δεν παρατηρήθηκαν υπολείµµατα χονδροειδών ή συµπυκνωµένων ζωοτροφών. Η κατανάλωση συµπυκνωµένου µίγµατος ήταν ψηλότερη στο σιτηρέσιο S παρά στο Α και τούτο γιά κάλυψη της διαφοράς σε ενέργεια µεταξύ αχύρου και τριφυλοσανού. Με εξαίρεση τη στατιστικά µεγαλύτερη πεπτικότητα της οργανικής ουσίας του σιτηρεσίου Α, η πεπτικότητα της ξηρής ουσίας και της πρωτεΐνης δεν ήταν στατιστικά σηµαντική µεταξύ των δύο σιτηρεσίων. Με βάση τα αποτελέσµετα της µελέτης συµπεραίνεται ότι δεν υπάρχει διαφορά στην αξιοποίηση της πρωτεΐνης από σόγια ή τριφυλοσανό, και οι ίδιες αποδόσεις µπορούν να επιτευχθούν από αγελάδες στις οποίες δίδεται άχυρο κριθαριού ή τριφυλοσανός αρκεί στο σιτηρέσιο µε άχυρο να παρασχεθεί πρόσθετη πρωτεΐνη από σόγια. INTRODUCTION Alfalfa (Medicago sativa) as fresh, silage or hay is an important feed ingredient and dietary protein source in intensive production systems throughout the world. Alfalfa, often called Queen of the Forages, has the highest feeding value of all commonly grown hay crops (Barnes and Gordon, 1972). Although alfalfa is an important forage crop for lactating cows, because of its high protein concentration, research has indicated that proteins in alfalfa are highly susceptible to degradation during field-wilting (Makoni et al., 1993) and ruminal fermentation (Broderick, 1985). These factors, may contribute to inefficient utilisation of potentially available N and depressed milk yield in lactating dairy cows (Broderick, 1985) despite the high initial N concentration in standing alfalfa. Performance of steers fed 60% alfalfa meal and 34% barley grain diet (143 g CP/kg DM) was better than that of steers given a diet of 34.5% barley grain, 19% soybean meal and 40.5% wheat straw (142 g CP/kg DM) (Horton and Nicholson, 1981). Furthermore, several producers noted that milk production increased when cows were fed legume/pasture instead of stored feed. In the study of Stiles et al. (1972) cows on alfalfa pasture produced more milk, fat and solids-non-fat than those grazing bromegrass. Similarly, Hoffman et al. (1998) demonstrated that cows fed alfalfa silage produced 1.6 kg milk more than cows fed perennial ryegrass silage. On the other hand, studies by Georghiades et al. (1987) with lactating cows (42±4 days in milk and an average initial milk yield 28.8 kg/day) showed no difference in protein utilisation from either soybean meal or alfalfa hay, and that similar milk yields can be produced by dairy cows fed either alfalfa hay or barley hay, provided that the protein content of barley hay will be adjusted to that of alfalfa by the addition of supplemental soybean meal. Due to low rainfall conditions and the shortage of irrigation water in many parts of the world, including the Mediterranean region, alfalfa cannot compete with cash crops or fruit trees, underlying the need for alternative roughage feed sources of poorer quality (i.e. cereal hays, cereal straws) produced from raifed crops. The objective of the present work was to study the effect of replacing alfalfa hay by barley straw on the lactation performance of Friesian cows in early lactation offered an iso-nitrogenous total ration. MATERIALS AND METHODS Forty four dairy Friesian cows were used. Animals were placed on the two experimental diets (Barley straw, S or Alfalfa hay, A) at 28±3 days post-partum based on their milk yield one week prior to allocation to treatments. The two experimental diets, were made iso-nitrogenous by offering one of two concentrate mixtures (Table 1). Cows within treatments were housed in two adjacent barns with adequately shaded area. The two roughages (Diet S:3.5 kg barley hay plus 3.5 kg barley straw; Diet A:3.5 kg barley hay plus 3.5 kg alfalfa hay/h/day) were group-fed from two separate feeding troughs. Concentrates were offered individually via a computerised feeding system in five equal meals at regular intervals throughout the day. Feed allowance, intended to cover maintenance, growth (first and second lactation 4
Table 1. Composition (%) of the two concentrate mixtures and chemical analyses (% Dry matter basis) of the concentrates and of roughages used Concentrate Barley Lucerne Straw hay hay S A Composition Rolled barley grain 61.3 67.8 - - - Rolled corn grain 10.0 10.0 - - - Soybean meal 23.6 15.0 - - - Wheat bran 2.5 4.6 - - - Dicalcium phosphate 0.25 0.25 - - - Limestone 1.8 1.8 - - - Salt 0.35 0.35 - - - Vit.-Trace element mixture a 0.2 0.2 - - - Chemical analysis CP 21.7±2.0 17.9±1.74 7.8±1.20 18.9±0.89 3.7±0.78 Ash 7.4±0.81 7.8±0.90 7.4±0.76 11.5±0.64 5.4±0.30 EE 2.2±0.2 2.3±0.2 1.8±0.18 2.2±0.14 1.6±0.18 Cfi 4.5±1.54 4.4±0.61 25.9±3.08 32.0±4.24 38.8±2.59 Acid detergent fibre (ADF) - - 34.1±7.67 37.8±4.50 45.4±4.10 Neutral detergent fibre (NDF) - - 53.3±1.33 45.6±3.68 75.5±7.00 Acid detergent Lignin (ADL) - - 3.9±1.66 7.7±1.21 5.4±2.70 D - - 62.3±1.40 55.4±2.50 47.2±6.10 a The vitamin-trace element mixture supplied 8000 I.U. vitamin A, 1000 I.U. vitamin D3, 8.5 I.U. vitamin E, 25 mg Mn, 1.75 mg I, 45 mg Zn, 30 mg Fe, 2 mg Co and 60 mg Mg per kilogramme (as fed basis) concentrate mixture. D in vitro digestibility of organic matter in the dry matter. cows) and milk production requirements (NRC, 1988) was adjusted once every fortnight. Body weight of the cows was recorded on two consecutive days at the beginning and at the end of the 63 day trial. Milk samples were analysed for fat, protein, ash and total solids (MAFF, 1973) once every fortnight. Feed samples were collected routinely and analysed for DM, OM, CP, EE, Cfi, ADF, NDF and ADL (Harris, 1970). Cows had free access to water and were milked by machine twice (05.00 and 15.00 h) daily. Data were analysed using a statistical model that accounted for treatments (S or A), lactation number (1, 2, 3, 4, 5 or 6) and treatment by lactation number interaction. Apparent digestion coefficients of the two experimental diets were measured using four mature Chios wether sheep of 72 kg body weight. Animals within diets were given the appropriate concentrate mixture and roughages at the same proportion as that consumed by the lactating cows. The animals were housed and fed in groups the experimental diets for 21 days before their transfer to the matabolic crates, where they remained for 15 days. The first eight days served as adaptation period and the next 10 days as the collection period. Collection, processing and analysis of feed and faecal samples were as outlined by Hadjipanayiotou (1982). Data were analysed by one-way analysis of variance (Steel and Torrie, 1960). RESULTS AND DISCUSSION There was only one case of a health (stomach) problem in treatment A in the last week on test; the milk yield of the last week was estimated based on the previous week milk yield and the weekly decline in milk yield by the other cows on the same diet, and its data were also used in the analysis. Cows on the S diet were heavier than those on diet A at the beginning (P<0.01) and at the end (P<0.05) of the trial. However, differences in body weight changes between treatments during the course of the trial were not significant (P>0.05). This should be ascribed to the fact that cows were fed according to their maintenance and production energy requirements (NRC, 1989). 5
There were no differences between treatments for initial milk yield and daily milk (P>0.05) and/or fat (FCM) corrected (4%) milk yield (P>0.05) during the course of the trial. This is in line with the data of Poore et al. (1993) where substitution of chopped wheat straw for alfalfa hay did not affect DMI, milk yield or milk composition. Similarly, in the study of Georghiades et al. (1987) there was no difference in protein utilization from either soybean or alfalfa hay, and similar milk yields were produced by dairy cows fed either alfalfa hay or barley hay, provided that the protein content of barley hay was adjusted to that of alfalfa hay by the addition of supplemental soybean meal. Broderick (1985) found that similar levels of forage DM from alfalfa forage and corn silage resulted in comparable production of milk and fat, but cows produced less protein and milk with depressed protein content when fed alfalfa silage or hay than when fed iso-nitrogenous diets based on corn silage and soybean meal. The latter was not the case in the present study. Milk fat (P<0.01) and TS (P<0.05) of cows on the S diet was greater than those of the A diet. Differences between diets for CP and ash content of milk were not significant (P>0.05). The higher milk fat content of cows on the S diet should be ascribed to the higher NDF, ADF and Cfi content of the finished diet, that was totally associated with the type of roughage. Not only the level of NDF but also the source of fibre (Hoover, 1986) and its physical form (Woodford and Murphy, 1988) are among the factors influencing physiological and lactation responses, and within the afore mentioned factors should be associated the higher fat content of cows on the S diet. Lactation number had a significant effect on initial and final weight (P<0.01) but not on weight gain. Similarly, lactation number had a significant effect (P<0.01) on daily milk and FCM yields, and concentrate intake. Initial and final body weight, as well as milk and FCM yield were greater with advancing lactation number. Interaction effects were not significant. The daily roughage allowance offered was completely consumed. Concentrate intake of cows on the S diet was higher (P<0.05) than that of cows on the A diet. This was partly due to the additional allowance offered to balance for the lower energy content of straw (6.28 MJ ME/kg) compared to alfalfa (7.95 MJ ME/kg) offered. The actual CP content of the two concentrate mixtures (S:19.31%, A:15.93% as fed) was greater than the values estimated (S:17.69, A:14.87% as fed) using CP values of 10, 8, 15 and 44% (as fed basis) for barley grain, corn grain, wheat bran and soybean meal, respectively. However, the actual CP content of the two total diets was relatively close (S:14.99%, A:14.60% as fed) and any differences in performance can be safely ascribed to the treatments imposed. The digestion coefficients of the two experimental diets are in Table 2. The experimental diet with alfalfa hay had significantly (P<0.05) greater OM digestibility; this can be explained by the lower digestibility of barley straw compared to alfalfa hay. The actual individual intake of each feed ingredient is in Table 3. The amounts offered during the collection period were completely consumed. Table 2. Digestion coefficients of the diets 6 Treatment S A SE Feed intake (g DM/day) Concentrate 559 570 31.1 Barley hay 113 122 6.5 Alfalfa hay - 130±0.0 - Straw 119±18.3 - - Digestibility (%) Dry matter 73.4 75.2 0.56 Organic matter 76.5 79.2 0.69 * Crude protein 76.4 78.4 1.66 * Significant at P<0.05.
Table 3. Performance of Friesian cows offered straw or alfalfa hay on iso-nitrogenous diets Treatment S A SE No. of cows 22 22 - Milk yield (kg/day) 30.2 31.6 0.90 NS FCM (4%) yield (kg/day) 28.5 29.0 0.75 NS Milk composition (%) Fat 3.78 3.37 0.101 ** CP 3.13 3.06 0.042 Ash 0.74 0.73 0.005 TS 11.69 11.17 0.164 * Initial BW (kg) 556 524 7.5 ** Final BW (kg) 574 549 8.8 ** BW change (kg) 17.4 25.0 4.37 Feed intake (kg/day) Concentrate 15.33 14.60 0.388 * Barley hay 3.5 3.5 - Alfalfa hay - 3.5 - Straw 3.5 - - NS not significant (P>0.05), * significant at P<0.05, ** significant at P<0.01. Although the DM and CP digestibility of the diet with alfalfa hay was somewhat higher than that with straw, differences did not reach significance. It is concluded that there is no difference in protein utilization from either soybean meal or alfalfa hay, and that similar milk yields can be produced by dairy cows fed either alfalfa hay, comprising 16% of the total diet, or barley straw (1:1 ratio) provided that the protein and energy content of barley straw is adjusted to that of alfalfa hay by the provision of additional concentrate of higher soybean meal content. ACKNOWLEDGEMENTS The author is grateful to G. Kyprianou, A. Photiou, Mary Karavia, Maria Theodoridou and the staff of the Central Chemistry Laboratory for skilled technical assistance. REFERENCES Barnes, R.F., and C.H. Gordon. 1972. In Alfalfa Science and Technology. American Society of Agronomy. Madison, Wisconsin. Broderick, G.A. 1985. Alfalfa silage or hay versus corn silage as sole forage for lactating dairy cows. Journal of Dairy Science 68:3262-3271. Georghiades, E., S. Economides, and M. Hadjipanayiotou. 1987. Effect of type of roughage on milk yield and milk composition of Friesian dairy cows. Miscellaneous Reports 29, Agricultural Research Institute, Nicosia, 5p. Hadjipanayiotou, M. 1982. Effect of sodium bicarbonate and of roughage on milk yield and milk composition of goats and on rumen fermentation of sheep. Journal of Dairy Science 65:59-65. Harris, L.E. 1970. Nutrition Research Techniques for Domestic and Wild Animals. Vol. 1. An International Record System for Analysing Samples. Logan, Utah. Hoffman, P.C., D.K. Combs, and M.D. Calser. 1998. Performance of lactating dairy cows fed alfalfa silage or perennial silage. Journal of Dairy Science 81:162-168. Horton, G.M.J., and H.H. Nicholson. 1981. Nitrogen sources for growing cattle fed barley and either wheat straw or dehydrated alfalfa. Journal of Animal Science 52:1143-1149. MAFF. 1973. Ministry of Agricultural Fisheries and Food. The Analysis of Agricultural Materials. Technical Bulletin 27. HMSO, London. Makoni, N.F., J.A. Shelford, S. Nakai, L.J. Fisher, and W. Majak. 1993. Characterization of protein fractions in fresh, wilted, and 7
ensiled alfalfa. Journal of Dairy Science 76:1934-1944. Poore, M.H., J.A. Moore, R.S. Swingle, T.P. Eck, and B.H. Brown. 1993. Response of lactating Holstein cows to fibre source and ruminal starch degradability. Journal of Dairy Science 76:2235-2243. Steel, R.G.D., and J.H. Torrie. 1960. Principles and Procedures of Statistics. McGraw- Hill, New York. Stiles, D.A., E.E. Bartley, G.L. Kilgore, F.W. Boren, R.L. Ott and J.G. Clark. 1972. Comparative value of alfalfa pasture, or alfalfa hay for lactating dairy cows. Journal of Animal Science 34:1620-1624. NCR, 1988. Nutrient Requirements of Domestic Animals. Nutrient Requirements of Dairy cattle. Sixth revised edition. National Academy Press, Washigton, D.C. P.I.O. 185/2003-400 Issued by the Press and Information Office, Nicosia Printed by Konos Ltd, tel. 22491419, Nicosia