EVALUATION OF ENERGY VALUE OF RUMINANT FEEDINGSTUFFS

U radu je iznesen povijesni razvoj i svojstva hranidbenih sustava i načina procjena energetske vrijednosti krmiva preživača. Energetske vrijednosti krmiva izražavaju se u netto energiji za laktaciju (NEL) i netto energiji za rast i tov (NERIT), a kao jedinica upotrebljava se megajoul (MJ/kg ST krmiva). Osnova sustava je metabolička energija (ME). Prikazani su najvažniji čimbenici koji utječu na iskorištenje metaboličke energije: razina hranidbe, metaboličnost energije te tip i razina proizvodnje. lznesena je netto energetska vrijednost različitih mjernih jedinica u MJ te su uspoređeni različiti energetski sustavi u potencijalnoj proizvodnji mlijeka.Historical development and characteristics of feeding systems and ways of evaluation of energy values of ruminant feedingstuffs are presented. Energy values of feeds are given as net energy for lactation (NEL) and net energy for growth and fattening (NEGF) in MJ/kg DM of feedstuffs. The base of the system is metabolizable energy (ME). Most factors effecting the use the ME are shown, e.g. feeding levels, metabolizability (q) of energy and type and level of production. Net energy values of different measuring units in MJ are given, and different energy systems related to potential milk and meat production are compared

A MODEL FOR ESTIMATING PROTEIN VALUE OF RUMINANT FEEDINGSTUFFS: METABOLIZABLE PROTEIN

Na temelju pregleda sadašnjih sustava procjene bjelančevinaste vrijednosti krmiva za preživače predlaže se zamjena dosadašnjeg sustava probavljivih sirovih bjelančevina s metaboličkim bjelančevinama u Hrvatskoj. Način procjene prati metabolički put bjelančevina u preživača koji je u obliku modela opisan u AFCR (1992). Metaboličke bjelančevine (MB) su jedinica bjelančevinaste vrijednosti krmiva koja se sastoji od u tankom crijevu probavljivih nerazgrađenih bjelančevine krme (PNRP) i mikrobnih sirovih bjelančevina (MSB). Sinteza MSB procjenjuje se na dva načina: (1) na temelju efektivno razgradljive bjelančevine (ERB) i (2) količine fermentirajuće metaboličke energije (FME). Kada je količina sintetizirane MSB iz ERB - MSP iz FME tada je ERB = MSB i obrnuto, za krmiva koja su sastojak obroka. Ukoliko se preživači hrane samo jednim krmivom (paša) bez dodataka tada je niža vrijednost MSB. Kao konstanta uzima se brzina oticanja digesta (r = 0.05/h) zato jer se preživači u Hrvatskoj hrane voluminoznim ili polukoncentratnim obrokom, a visina hranidbe nije veća od 2 x uzdržne potrebe. Količina FME (MJ/kg ST) = Me - (0.035 x MEᴍs + 0.015 x NRP ME ferm), a sinteza MSB (g/kg ST) = 10 x FME (MJ/kg ST). Data je tablica potrebnih koeficijenata (%) za izračunavanje MB: topivosti bjelančevina, razgradljivosti netopive bjelančevine i bjelančevina netopiva u kiselom detergentu (neprobavljiva nerazgradljiva bjelančevina za uobičajena krmiva u Hrvatskoj.Based on a review of present system of evaluation of protein value feedstuffs for ruminants, the exchange of the existing digestible crude protein system with metabolizable protein is suggested in Croatia. The method of evaluation follows protein metabolism in ruminants described as a model in AFRC (1992). Metabolizable protein (MP) is the unit of protein value of feedingstuffs consisting of in the small intestine digestible undegraded protein (DUP) and microbial crude protein (MCP). Synthesis of MCP is evaluated in two ways: (1) based on the effective degradable protein (EDP) and (2) the amount of fermentable metabolizable energy (FME) of feedstuffs. When the amount of synthesized MCP from EDP is – MCP from FME, then EDP = MGP and the reverse; that is valid for feedingstuff as a component of a diet. lf the ruminants are fed only single feedingstuffs (pasture) without supplements, then the value is lower. Rumen digest outflow rate (r = 0.R05/h) is constant because ruminants in Croatia are fed only forage of forage (r = 0.045) to concentrate (r = 0,058 ratio) 60:40% in diet DM, and r is 0.6*0.045+0.4*0.058 = 0.05; so the corresponding feeding level is not higher than 2x maintenance. The amount of FME (MJ/kg DM) = ME - (0.035xMEfat + 0.015 x UDP + MEferm) and synthesis of MCP (g/kg DM) = 10xFME (MJ/kg DM).Table of requirement coefficients (%) for calculation of MP is suggested: solubility of protein effective degradability of insoluble protein and acid detergent insoluble protein (indigestible undegradable protein) for common feedingstuffs in Croatia

NUTRIENT REQUIREMENTS OF GOATS

U ovom radu prikazane su hranidbeno-fiziološke osobitosti koza i hranidbene potrebe mliječnih koza, jarčeva i jaradi. lznesen je način procjenjivanja i tablice potreba koza u netto energiji, metaboličkim bjelančevinama i mineralima, te kapacitet uzimanja krmiva i ješnost krmiva. Svi izneseni podaci su temeljeni na INRA (1988) normativima.Feeding and physiological characteristics of goats are presented such as nutrient requirements for dairy goats, male goats and kids. Simplified models describe the nutrient requirement of goats - netto energy, metabolizable protein and minerals. Also are shown the tables of nutrient requirements, feeds intake capacity and feeds consumption. All prosented data are based on INRA (1988) standard

Relationship between the Physical Properties of Maize Kernel and Metabolizable Energy for Pigs

Recent research indicated that the physical properties of maize kernels may be used to evaluate its nutritional value. Therefore, the main objective was to determine the relationships between kernel physical properties and metabolizable energy (ME) for pigs in commercial maize hybrids widely grown in Croatia. Field experiment was conducted in Baranja over two growing seasons with 11 maize hybrids (six domestic hybrids from Bc Institute and five introduced Pioneer hybrids). Investigated hybrids belonged to various maturity groups (FAO 200-600). Growing season significantly affected kernel thickness, kernel length, test weight and ME for pigs, despite similar average 1000-kernel weight in both years of field research. Hybrids differed signifiantly in kernel length, kernel width, kernel thickness, test weight and 1000-kernel weight as well as in ME. The shortest-season hybrid Bc282 had the smallest 1000-kernel weight (on average 314 g), but the largest test weight (on average 79.8 kg/hl) and high ME (on average 16.70 MJ/kg). The smallest test weight and ME was found for hybrid PR36K67 (FAO 490) which had the highest kernel length (13.4 mm on average) and 1000-kernel weight (438g on average), and consequently, low kernel sphericity. Test weight weakly correlated with kernel thickness and kernel sphericity, while it positively correlated with ME. The highest ME had hybrids Bc 572, Bc 462 and PR34B23, while five hybrids had slightly lower values. Of all kernel physical properties, the test weight appears to be most reliable indicator for assessing ME for pigs in the kernels of commercial maize hybrids

Pigmentation Efficiency of Croatian Corn Hybrids in Egg Production

To achieve desirable egg yolk colour producers enhance laying hen’s diet with pigments, usually from synthetic origin. More recently, consumers have become more concerned about the use of synthetic additives in foods and feeds and interest in natural alternatives has increased. In Croatia, corn grain is the base of laying hen’s diet, but contribution of corn carotenoids to egg yolk colour was neglected. Therefore, aim of this research was to explore the pigmentation effi ciency of corn grain hybrids in egg production. Three cages, each with three laying hens were allotted to one of the eight dietary treatments differentiated only in corn hybrid (56 % of diets) and fed for 63 days. There were no added synthetic pigments in the treatments. Total carotenoid content of the corn grain and egg yolk was quantifi ed spectrophotometrically as β-carotene equivalents, while colour measurements of egg yolk were recorded instrumentally using a Minolta Chromameter (CR-410) in the CIE L* a* b* space, and subjectively by Roche yolk colour fan (RYCF). The level of total carotenoids in corn grain ranged from 17.32 to 31.52 mg/kg. Total carotenoids in egg yolks signifi cantly differ (P10) could be achieved with higher portion of corn grain in the diet. In addition, the CIE a* value correlated well with RYCF scale and therefore could be used for more objective colour measurements of egg yolk