The effect of milk replacer intake and level of crude protein in starter feed on dairy bull calf pre-weaning growth parameters and the carry-over effect on post-weaning growth and profitability

Date
2022-12
Journal Title
Journal ISSN
Volume Title
Publisher
Stellenbosch : Stellenbosch University
Abstract
ENGLISH ABSTRACT: Currently worldwide, during the liquid phase, calves are generally fed conventional volumes (4 L/day) of milk replacer (MR) with ad libitum starter feed ranging between 160 g CP/kg DM and 210 g CP/kg DM. Dairy bull calves are unwanted in the dairy industry, therefore they are normally sold to feedlots where they are raised as veal or dairy beef. Calves can however consume higher volumes of MR than the conventional volume which can result in greater weight gains. A positive correlation between dietary crude protein (CP) intake and protein deposition in body tissue is also known. Thus, feeding calves higher volumes of MR combined with high CP starter can potentially increase dairy bull calves more profitable. In practice improved feed efficiency of calves leads to higher profitability. A two part study was therefore conducted with the first phase evolving a pre-weaning MR and CP starter feed phase and a secondary part investigating the effect of pre-weaning treatments on the post-weaning backgrounding phase performance. In the first part of the study, three different volumes of MR (4, 6 & 9 L/day) and two different CP starter feeds (210 g/kg DM & 260 g/kg DM) were fed to Holstein-Friesian bull calves to evaluate pre-weaning growth parameters. The treatments were (1) 4 L/day of MR, 210 g CP/kg DM starter feed (LL); (2) 6 L/day of MR, 210 g CP/kg DM starter feed (LM); (3) 9 L/day of MR, 210 g CP/kg DM starter feed (LH); (4) 4 L/day of MR, 260 g CP/kg DM starter feed (HL); (5) 6 L/day of MR, 260 g CP/kg DM starter feed (HM) and (6) 9 L/day of MR, 260 g CP/kg DM starter feed (HH). All calves were weaned after 60 days of age. The MR volume of calves fed the 6 and 9 L/day were stepped down from day 46 to increase the DMI of the starter feed before weaning. Weekly body weights and allometric growth measurements were taken to evaluate body weight growth and allometric growth differences between treatments. Starter feed dry matter intake of the calves fed 4 and 6 L/day of MR were significant greater (P < 0.05) than for calves fed 9 L/day. No differences in ADG, growth parameters and gain over the period were observed between MR volume treatments. Average daily gain and gain over period however were significantly different (P < 0.05) between the two CP starter feeds. The final weight of the calves did not differ between the starter feeds, but the final weight of calves fed 6 L/day of MR were significantly (P < 0.05) higher than from the calves fed 4 L/day MR while the 9 L/day MR group final weight did not differ from any of the other treatments. None of the allometric growth parameters differed between treatments. The feed conversion ratio of the calves did not differ significantly among all six treatments. During the post-weaning phase of the study, all calves were background for 80 days on ad libitum grazing while daily supplemented with the same concentrate feed at 2 kg per calf per day. The objective of the secondary phase was to evaluate the carry-over effects on the post-weaning growth and profitability of Holstein-Friesian steers. After 80 days of backgrounding, the calves were sold to a commercial feedlot. Based on this income, the related profitability per animal per treatment were calculated. No carry-over effects were observed for calves fed higher volumes of MR nor higher CP starter feed during the pre- weaning phase, since the gain over period during the post-weaning phase were not different amongst the treatment groups, except for treatment LL which did not differ significantly from treatments HM and HH. Treatment LL resulted in numerical slower growth both during the pre- weaning and post-weaning period. The latter treatment differed significantly (P < 0.05) from treatments LM, HL, HM and HH during the pre-weaning period, however only differed significantly (P < 0.05) from treatments LM, LH and HL during the post-weaning period. The total cost of raising the calves differed significantly (P < 0.05) for all treatments and this difference was mostly the result of the feed cost during the pre-weaning phase. Treatment HL was numerically, the most cost effective with the highest profit, while calves fed 9 L of MR resulted in the lowest profit. However, the profit of treatment LL and HH were significantly lower (P < 0.05) than treatment HL but did not differ significantly from the other treatments. The lack of response in treatment LL during the pre-weaning period could be attributed to nutritional insult, therefore the lack of response was carried over in the post-weaning period. Feed costs vary from season to season, therefore the total cost of raising can vary over season and between geographical locations. In this trial, however feeding calves the conventional volume of MR with a high CP starter resulted in the most profitable approach to raising dairy beef.
AFRIKAANSE OPSOMMING: Kalwers tydens die melkfase word huidig wêreldwyd oor die algemeen ‘n konvensionele volume van (4 L/dag) melkvervanger tesaam met ad libitum aanvangspille wat wissel tussen 160 g CP/kg DM en 210 g CP/kg DM gevoer. In die suiwelbedryf word bulkalwers as ongewens beskou en daarom word die bulkalwers normaalweg aan voerkrale verkoop waar hulle as kalfs- of suiwelbeesvleis grootgemaak word. Kalwers kan egter hoër volumes melkvervanger as die konvensionele volume inneem wat tot groter massatoename kan lei. ’n Positiewe korrelasie tussen ruproteïeninname en proteïenneerlegging in die liggaamsweefsel is ook bekend. Dus kan die voeding van groter volumes melkvervanger en hoër ruproteïen- aanvangspille moontlik die grootmaak van melkbulkalwers meer winsgewend maak. In die praktyk, lei verbeterde voerdoeltreffendheid van kalwers tot hoër winsgewendheid. ’n Tweeledige studie is dus uitgevoer met die eerste fase wat ’n voorspeense melkvervanger en ruproteïenaanvangspille fase behels het en ’n tweede fase wat die effek van voorspeense behandelings op die na-speense prestasie vir voorbereiding van die voerkraal ondersoek het. In die eerste deel van die studie was drie verskillende melkvervanger volumes (4, 6 & 9 L/dag) en twee verskillende ruproteïenvlakaanvangspille (210 g/kg DM & 260 g/kg DM) aan Holstein-Friesian bulkalwers gevoer om die voorspeense groeiparameters te evalueer. Die behandelings was (1) 4 L melkvervanger, 210 g CP/kg DM aanvangspille (LL); (2) 6 L melkvervanger, 210 g CP/kg DM aanvangspille (LM); (3) 9 L melkvervanger, 210 g CP/kg DM aanvangspille (LH); (4) 4 L melkvervanger, 260 g CP/kg DM aanvangspille (HL); (5) 6 L melkvervanger, 260 g CP/kg DM aanvangspille (HM); (6) 9 L melkvervanger, 260 g CP/kg DM aanvangspille (HH). Al die kalwers is op die ouderdom van 60 dae gespeen. Die melkvervangervolume van kalwers wat 6 en 9 L/dag gevoer is, is vanaf dag 46 verlaag om effektiewe droë materiaal inname (DMI) voor speen te verseker. Die aanvangspilinname was betekenisvol hoër (P < 0.05) vir kalwers wat laer volumes melkvervanger ontvang het. Weeklikse liggaamsmassa en liggaamsmates was geneem om die allometriese groeiverskille tussen die behandelings te evalueer. Die aanvangspille DMI van kalwers wat 4 en 6 L/dag gevoer was, was betekenisvol (P < 0.05) beter as die van kalwers wat 9 L/dag gevoer was. Daar was geen verskille in gemiddelde daaglikse toename (GDT) en die totale groei oor die tydperk tussen die melkvervangervolumes waargeneem nie. Die gemiddelde daaglikse toename en die totale groei oor die tydperk was egter betekenisvol (P < 0.05) verskillend tussen die twee ruproteïenaanvangspille. Die finale massa van die kalwers het nie betekenisvol verskil tussen die aanvangspille nie, maar die finale massa van kalwers wat 6 L/dag melkvervanger ontvang het, het betekenisvol verskil (P < 0.05) van die kalwers wat 4 L/dag ontvang het. Terwyl die finale massa van kalwers wat 9 L/dag melkvervanger ontvang het, het nie betekenisvol verskil van die ander behandelings nie. Geen van die allometriese groei parameters het van mekaar verskil nie. Voeromsetvermoë van die kalwers het geen verskille tussen die ses behandelings getoon nie. Tydens die na-speen tydperk van die studie was alle kalwers voorberei vir ’n voerkraal vir 80 dae op ad libitum weiding terwyl 2 kg per kalf per dag van dieselfde kragvoer daagliks aangevul is. Die doel van die tweede fase was om die oordragingsvermoë van die voor speense behandelings op die na-speense groei en winsgewendheid van Holstein-Friesian osse te evalueer. Na die 80 dae se voorbereiding op die weiding, is die kalwers aan ‘n kommersiële voerkraal verkoop. Op grond van hierdie inkomste, is die winsgewendheind per dier per behandeling bereken. Daar is geen oordragingseffek waargeneem vir kalwers wat hoër volumes melkvervanger met ‘n hoë ruproteïenaanvangspille ontvang het nie, aangesien die totale massatoename tydens die na-speen tydperk nie betekenisvol tussen verskillende behandelingsgroepe verskil het nie. Behandeling LL het gelei tot numeriese stadiger groei gedurende die voor-speen- en na-speentydperk. Die laasgenoemde behandeling het wel betekenisvol verskil (P < 0.05) van behandelings LM, HL, HM en HH gedurende die voor speentydperk, maar het slegs betekenisvol verskil (P < 0.05) van behandelings LM, LH en HL gedurende die na-speentydperk. Die totale koste om kalwers groot te maak het betekenisvol verskil (P < 0.05) vir alle behandelings en hierdie verskil en kon aan voerkoste verskille tydens die voor-speentydperk toegeskryf word. Behandeling HL (4 L/dag melkvervanger en 260 g/kg ruproteïenaanvangspille) was numeries, die mees koste-effektiewe met die hoogste wins, terwyl kalwers wat 9 L/dag melkvervanger ontvang het, die laagste wins tot gevolg gehad het. Die wins van behandelings LL and HH was betekenisvol laer teenoor behandeling HL, maar het nie betekenisvol verskil van die ander behandelings nie. Die gebrek aan respons van behandeling LL gedurende die voor-speentydperk was as gevolg van ‘n tekort aan nutrientinname, daarom is die gebrek aan respons in die naspeense tydperk oorgedra. Die voerkoste verskil tussen seisoene, daarom kan die totale koste om kalwers groot te maak verander oor seisoene en verskillende geografiese gebiede. In hierdie studie, het die kalwers wat die konvensionele volume (4 L/dag) melkvervanger ontvang het tesame met ‘n hoë ruproteïen kruipvoer (260 g/kg), tot die mees koste-effektiewe manier gelei om suiwelbulkalwers groot te maak.
Description
Thesis (MScAgric)--Stellenbosch University, 2022.
Keywords
Milk replacer, Calves -- Weaning -- Economic aspects, Calves -- Growth -- Nutritional aspects, Crude protein, Calves -- Feeding and feeds, Holstein-Friesian cattle -- Feeding and feeds, Proteins in animal nutrition, UCTD
Citation