The effect of pasture biostimulant treatment and decreased concentrate supplementation on pasture production and the production and profitability of pasture fed lactating Jersey cows

Date
2023-03
Journal Title
Journal ISSN
Volume Title
Publisher
Stellenbosch : Stellenbosch University
Abstract
ENGLISH ABSTRACT: Pasture-based dairy farmers are struggling against rising feed costs and stagnant milk prices. To combat the effect of increasing feed prices on the profitability of a pasture-based dairy farm, levels of concentrate supplementation can be decreased to lower input costs. It is evident that the profitability of a pasture-based dairy farm can be improved through the reduction in concentrate supplementation level while (where possible) the herbage allowance and quality is increased. Profitability studies however failed to include the effect of increase of land use, due to an increased pasture allowance that leads to decreased stocking rate. Plant-biostimulants like fulvic acid and bioflavonoids can increase pasture quantity, thereby improving stocking density. The gap in profitability studies to examine the economic effect of a combined application of reduction of concentration supplementation and the increase in pasture quantity and quality through the application of fulvic acid and bioflavonoids has to the best of the author’s knowledge not been investigated. This study aimed to quantify the effect of reduced concentrate supplementation rates in the production of pasture fed lactating Jersey cows. Simultaneously, the effect of plant-biostimulant treatment, fulvic acid and bioflavonoid, on a mixture of perennial ryegrass and clover pasture was also studied. Lastly, the effect of reduced concentrate feeding and increased pasture allowance on the profitability of Jersey cows was investigated. For the first study, a 3.3 Ha pasture paddock consisting of homogenic one-year old perennial ryegrass and clover pasture were used. A randomized block design with three blocks and two treatment factors (each at two levels) were adopted viz. 12 experimental plots. The first factor was the grazing cycle in two contrasting seasons (summer 2021 and winter 2021). For the second factor an untreated control was compared to a commercial plant-biostimulant cocktail treatment. Two plots per block were treated with the biostimulants. Biostimulant treatment affected pasture botanical composition, resulting in lower ryegrass content in both a winter and summer grazing cycle (P < 0.01). The biostimulant treatment had no effect on the chemical composition nor the total yield of perennial ryegrass/clover pasture within a seasonal grazing cycle. There was however a tendency (P = 0.08) for biostimulant treatment to improve herbage yield in the summer grazing cycle. For the second study twenty-four lactating multiparous Jersey cows for both a winter and summer season were used. A randomized block design was used where cows were randomly assigned to one of two treatments: four kilogram concentrate supplement per day with 12 kg (DM) pasture allowance (LC) and eight kg concentrates supplement per day with 8 kg (DM) pasture allowance (HC). The long-term effects of reduced concentrate supplement feeding were also investigated after the completion of the winter and summer trials. During the long-term evaluation, the cows in both treatment groups grazed pasture ad lib with 4 kg day⁻¹ concentrate supplementation. Milk yield, 4% fat corrected milk yield and energy corrected milk yield remained unchanged regardless of concentrate supplementation rate in both the summer and winter trials. Milk protein yield and milk protein content were not affected by treatment in the winter trial. In the summer trial treatment influenced milk protein yield (P < 0.01) but not milk protein content. Milk protein yield was higher for the HC treatment. Milk fat yield, milk fat content, somatic cell count, body weight and condition score were not affected by treatment in both the winter and summer trials. Milk urea nitrogen levels was affected by concentrate supplementation rate (P < 0.01) in the winter trial but not in the summer trial. Milk urea nitrogen levels were higher for cows in the LC treatment (9.11 mg N dL⁻¹) than cows in the HC treatment (6.56 mg N dL⁻¹) during the winter trial. The cows in the LC and HC treatment groups managed to maintain their body condition score and body weight in both the winter and summer trials up to 150 days after the end of each respective trial. Milk yield after each trial followed the shape of a standard lactation curve and milk yield gradually decreased towards the drying off period. Lastly, the effect of reduced concentrate feeding and increased pasture allowance on the profit margin over feed cost per cow day⁻¹, per cow hectare⁻¹ and per cow month⁻¹ of multiparous lactating Jersey cows in the summer and winter seasons was determined. In the winter trial lowering of concentrate supplementation proved to be profitable when enough good quality pasture is available based on both per cow per day (P = 0.03) and monthly performances (P = 0.04). There was also no negative effect of reduced concentrate supplementation levels on per cow per hectare performance. The only benefit of reduced supplementation levels in the summer trial was based on the profit margin per cow per day. Higher supplementation levels proved more profitable (P < 0.05) on per cow per hectare performance with no difference in profit margin between treatments based on a monthly basis. Although biostimulant application did not improve pasture yield, farmers can still increase farm profitability through reduced supplement rates and increased pasture allowance when good quality pasture is available.
AFRIKAANSE OPSOMMING: Weidingsgebaseerde melkboere voer ‘n stryd teen stygende voerkoste en stagnerende melkpryse. Om die effek van stygende voerpryse op die winsgewendheid van 'n weidingsgebaseerde melkplaas te bekamp, kan kragvoerpeille verlaag word ten einde insetkoste te verlaag. Dit is bewys dat die winsgewendheid van 'n weidingsgebaseerde melkplaas verbeter kan word deur die verlaging in kragvoer vlakke, waar moontlik, mits die weidingskwantiteit en - kwaliteit verhoog word. Winsgewendheid studies het egter nagelaat om die effek van toename in grondgebruik in berekening te bring omdat 'n verhoogde weidingsbehoefte tot verlaagde veelading sal lei en dus 'n beduidende afname in die winsgewendheid per hektaar kan veroorsaak. Deur die gebruik van plant-biostimulante soos fulviensuur en bioflavonoïede kan weidingskwantiteit verhoog word, wat drakrag van die weiding sal verhoog. Die leemte in winsgewendheid studies om die ekonomiese effek van 'n gekombineerde verlaagde kragvoerpeile en ‘n toename in weidingskwantieit en -kwaliteit, deur die behandeling van fulviensuur en bioflavonoïede, te evalueer is na die beste van die skrywers se kennis nog nie voorheen ondersoek nie. Die doelwit van hierdie studie was om die effek van verlaagde kragvoerpeile op die melkproduksie van weidingsgebaseerde lakterende Jersey koeie te kwantifiseer. Terselfdertyd is die effek van biostimulant, fulviensuur en bioflavonoïed-behandeling op 'n mengsel van meerjarige raaigras en klawerweiding ook ondersoek. Laastens is die gekombineerde effek van verlaagde kragvoerpeil en verhoogde weidings allokasie op die winsgewendheid van lakterende Jersey koeie ondersoek. 'n 3.3 Ha weidingskamp bestaande uit homogene meerjarige raaigras en klawerweiding is in die eerste studie gebruik. 'n Ewekansige blokontwerp met drie blokke en twee behandelingsfaktore is gebruik nl. 12 eksperimentele kampe. Die eerste faktor was die weidingsiklus in twee kontrasterende seisoene (somer 2021 en winter 2021). Vir die tweede faktor is onbehandelde weiding vergelyk met weiding wat met 'n kommersiële biostimulant behandel is. Twee kampe per blok is met die biostimulant mengsel behandel. Biostimulant behandeling het die weiding se botaniese samestelling beïnvloed, met laer (P < 0.01) raaigras inhoud in beide 'n winter- en somer weidingsiklus. Die biostimulant behandeling het geen invloed op die chemiese samestelling of die totale opbrengs van die meerjarige raaigras/klawer weiding binne 'n seisoenale weidingsiklus gehad nie. Daar was egter 'n neiging (P = 0.08) vir biostimulant behandeling om weidings-opbrengs in die somer weidingsiklus te verhoog. Vir die tweede studie is vier-en-twintig lakterende Jersey-koeie vir beide 'n winter en somer seisoen gebruik. 'n Ewekansige blokontwerp is gebruik waar koeie lukraak aan een van twee behandelings toegedeel is: vier kilogram kragvoer per dag met 12 kilogram weidingstoelaag (LC) en agt kilogram kragvoer per dag met agt kilogram weidingstoelaag (HC). Die langtermyn-effekte van verlaagde kragvoervoeding na afloop van die winter- en somer proewe is ook ondersoek. Tydens die langtermyn-evaluering het die koeie in albei behandelingsgroepe weiding ad libitum ontvang met 'n 4 kg per koei per dag kragvoerpeil. Melkopbrengs, 4% vetgekorrigeerde melkopbrengs en energiegekorrigeerde melkopbrengs het onveranderd gebly ongeag die kragvoer peil in beide die somer- en winterperiodes. Melkproteïenopbrengs en melkproteïeninhoud is nie deur behandeling in die winterproef beïnvloed nie. In die somerproef het die kragvoer peil opbrengs van melkproteïen (P < 0.01) beïnvloed, maar nie die melkproteïeninhoud nie. Die melk proteïen opbrengs was hoër vir die HC behandeling. Melkvetopbrengs, melkvetinhoud, somatiese seltelling, liggaamsmassa en liggaamskondisie teling is nie deur die behandeling in beide die winter- en somerproewe beïnvloed nie. Melk ureum stikstofvlakke is deur kragvoerpeil (P < 0.01) in die winterproef beïnvloed, maar nie in die somerproef nie. Melk ureum stikstofvlakke was hoër vir koeie in die LC behandeling (9.11 mg N dL⁻¹) teenoor koeie in die HC behandeling (6.56 mg N dL⁻ ¹) gedurende die winterproef. Die koeie in die LC- en HC-behandelingsgroepe het daarin geslaag om hul liggaamskondisie telling en liggaamsmassa in beide die winter- en somerproewe tot 150 dae na die einde van elk van die onderskeie proewe te handhaaf. Melkopbrengs na elke proef het 'n standaard laktasie kurwe gevolg met melkopbrengs wat geleidelik afgeneem het tot by die opdroog periode. Laastens is die gekombineerde effek van verlaagde kragvoerpeil en verhoogde weidings toedeling op die wins oor voerkoste per koei per dag, per koei per hektaar en per koei per maand van die lakterende Jersey koeie in die somer- en winter seisoene bepaal. In die winterproef was die verlaging van kragvoerpeil meer winsgewend mits voldoende weiding van goeie gehalte beskikbaar is op grond van winsmarge per koei per dag (P = 0.03) en maandelikse prestasies (P = 0.04). Geen nadelige effek van verlaagde kragvoerpeil op per koei per hektaar op diereprestasie is waargeneem nie. Die enigste voordeel van verlaagde kragvoer in die somerproef was gebaseer op die winsmarge per koei per dag. Hoër kragvoerpeile was meer winsgewend (P < 0.05) indien per koeie per hektaar gemeet was met geen verskil in winsmarge tussen behandelings gebaseer op 'n maandelikse basis nie. Alhoewel biostimulantbehandeling nie weidingsopbrengs verbeter het nie, kan boere steeds plaas winsgewendheid verhoog deur verlaagde kragvoerpeille en verhoogde weidings toedeling mits voldoende goeie kwaliteit weiding beskikbaar is.
Description
Thesis (MScAgric)--Stellenbosch University, 2023.
Keywords
Citation