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- Jardstedt, Mikaela, et al.
(author)
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Feed intake and urinary excretion of nitrogen and purine derivatives in pregnant suckler cows fed alternative roughage-based diets
- 2017
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In: Livestock Science. - : Elsevier BV. - 1871-1413 .- 1878-0490. ; 202, s. 82-88
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Journal article (peer-reviewed)abstract
- This study compared intake of alternative roughage-based diets and of common late-cut grass silage and related intake to urinary nitrogen (N), urea-N and purine derivative (PD) excretion, where PD is an indicator of rumen microbial crude protein (MCP) synthesis. Total urine was collected from 36 Hereford cows, blocked into three groups based on expected calving date. Cows within calving groups were randomly assigned to one of four roughage diets: common mixed grass silage (MGS), festulolium silage plus urea (FLS), reed canarygrass silage (RCS) and barley straw plus urea and rapeseed meal (BRM). Diet crude protein (CP) content was classified into five fractions (A, B-1, B-2, B-3 and C), based on degradability characteristics. Feed intake and urinary excretion data were analysed by ANOVA in a randomised block design. To further explain the ANOVA results, multiple regression analyses were conducted to study relationships between intakes of total N (g/d); sum of the CP fractions A, B1 and By (AB(1)B(2); g/d), most of which is considered rumen-degradable; digestible organic matter (DOMI; kg/ d); protein balance in the rumen (g/kg dry matter); and urinary excretion of N, urea-N (g/d) and PD (mmol/d). Urinary N and urea-N excretion was positively related to N intake and was better explained by N intake than intake of AB(1)B(2). Feeding BRM resulted in the lowest N intake and urinary N output (P < 0.001). Cows fed MGS, FLS and RCS had similar N intake, but urinary N and urea-N excretion was significantly higher (P < 0.001) in cows fed RCS, which probably was attributable to the significantly lower DOMI of this diet (P < 0.001). Furthermore, addition of DOMI to N intake in the multiple regression analysis increased the proportion of explained variation in urinary N and urea-N excretion. The MGS and FLS diets stimulated rumen MCP production to a greater extent than the BRM diet, as indicated by the higher urinary output of PD in cows fed the grass silage-based diets (P < 0.001). Diet had no significant effect on urinary PD excretion when expressed per kg DOMI. Overall mean urinary creatinine excretion was 0.197 +/- 0.047 mmol/kg body weight, with no significant effect of diet. This study showed that intake of both N and DOM need to be assessed when choosing a suitable alternative roughage diet for suckler cows, in order to prevent undesirable losses of urinary N.
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| 3. |
- Jardstedt, Mikaela, et al.
(author)
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Intake and feed utilization in two breeds of pregnant beef cows fed forages with high-fiber concentrations
- 2018
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In: Journal of Animal Science. - : Oxford University Press (OUP). - 0021-8812 .- 1525-3163. ; 96, s. 3398-3411
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Journal article (peer-reviewed)abstract
- Hereford and Charolais beef cows (n = 24 per breed) were used to study the effect of breed and to evaluate late-cut reed canarygrass (RC) and whole-crop oats plus urea (WCO) compared with late-cut timothy (TG) with respect to feed intake and digestibility, rumination time, fecal particle size (PS) distribution, N excretion, and ruminal microbial CP production (MCP). The TG and RC were cut at flowering and WCO at hard dough stage of maturity. Cows were group-housed, 6 groups per breed, and fed 3 diets ad libitum in 3 periods. The study was designed as two 3 x 3 Latin squares amalgamated to form a 3 x 6 rectangle for each breed. All data were statistically analyzed on group level. Indigestible NDF (iNDF) and urinary creatinine excretion were used as markers to estimate apparent diet digestibility and daily urine volume, respectively. Fecal PS distribution was determined by dry sieving, and ruminal MCP synthesis was estimated based on urinary output of purine derivatives. The TG diet had a higher apparent digestibility of OM and NDF (P < 0.001) than RC and WCO, which did not differ. The TG diet resulted in the greatest daily DMI, followed by WCO and RC (P < 0.001). Intake of NDF (NDFI, kg/d and % of BW) was greatest for TG, followed by RC and WCO (P < 0.001). Rumination time per kg DMI was longest for RC (P < 0.001), and RC and WCO resulted in longest rumination time per kg NDFI (P < 0.001). The WCO diet resulted in the largest geometric mean fecal PS and proportion of large particles and in the smallest proportion of small particles, whereas the opposite was found for RC, with TG being intermediate (P < 0.001). Intakes in kg per day were higher for Charolais than for Hereford (P = 0.002), but no breed effect was detected when intake was expressed in relation to BW. Charolais ruminated longer per kg NDFI corrected for BW (P = 0.02) and had smaller mean fecal PS (P = 0.049) than Hereford. Total N excretion was highest for RC and lowest for WCO (P < 0.001). The TG diet stimulated MCP production to a greater extent than RC and WCO (P < 0.001). The results indicate that late-cut RC and WCO could be suitable alternatives to late-cut TG for ad libitum feeding of early pregnant beef cows, and that intake was associated with cow BW, but not with breed. The variations in NDF and iNDF concentrations between forage diets were reflected in their effects on intake, rumination, apparent digestibility, and fecal PS.
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| 6. |
- Jardstedt, Mikaela
(author)
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Roughage Feeding of Suckler Cows during Winter : intake, utilization and energy status in pregnant cows
- 2019
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Doctoral thesis (other academic/artistic)abstract
- Feeding late cut forage is a common strategy to provide pregnant suckler cows with feed of suitable nutritional quality during ad libitum feeding regimes. Despite this method, commonly grown grasses may result in overfeeding with energy and protein in relation to cow nutrient demands. The aim of this thesis was to evaluate alternative types of highfibre roughages and their effects on feed intake, utilization, and cow energy status, to improve the effectiveness of feed resource use to spring-calving suckler cows. In a first study, the effects of forage diet; timothy silage, reed canarygrass silage, and whole-crop oat silage, on intake, digestibility, rumination time, faecal particle size and nitrogen (N) utilization were studied in mid-pregnant cows of Hereford and Charolais breeds. In two further studies, feed intake, N utilization, cow energy status and metabolic profile before and around parturition, and calf performance, were investigated in Hereford cows fed timothy-meadow fescue silage, festulolium silage, reed canarygrass silage or barley straw supplemented with rapeseed meal during pregnancy. Although cut at similar stage of maturity, all perennial grasses exhibited variations in digestibility and fibre characteristics, which elicited differences in intake and utilization. Traditional timothy and timothy-meadow fescue silage, and festulolium silage, resulted in overfeeding and increased body weight (BW) and body condition (BCS) during pregnancy, whereas the low digestibility of the reed canarygrass and barley straw diets resulted in a catabolic state and losses of BW and BCS prepartum. Intake appeared to be proportional to cow BW and not affected by the breed itself. Nitrogen utilization was improved with increased intake of digestible organic matter. There is potential to increase effectiveness of the current suckler cow feeding by choosing alternative forages of low digestibility and rich in fibre. This may reduce feed intake and accompanied feed costs, and risk of overfeeding with energy and protein, without negative effects on cow performance.
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- Jardstedt, Mikaela, et al.
(author)
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Rödalger som metanreducerande fodertillskott till nötkreatur - litteraturstudie och kostnadsberäkningar av att utfodra ett algtillskott i olika uppfödningsmodeller
- 2021
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Reports (other academic/artistic)abstract
- Den tropiska rödalgen Asparagopsis Taxiformis har i ett flertal laboratoriestudier visat sig ha stor potential att minska metanutsläppen från idisslares matsmältning, utan att ge några negativa effekter på fermentationen i vommen. Rödalgens metanreducerande effekt antas bero på dess relativt höga innehåll av halogenerade metananaloger, varav bromoform förekommer i högst koncentration. Dessa ämnen förhindrar de metanbildande arkéerna i vommen från att omvandla vätgas och koldioxid till metan. Antalet djurstudier som genomförts i syfte att undersöka rödalgens effekt på metanproduktionen hos idisslare är dock få, men de som hittills publicerats har även de visat lovande resultat. Bland annat minskade metanproduktionen per dag med 59% respektive 98% för stutar som gavs en grovfoderrik (60% grovfoder) respektive kraftfoderrik (8% grovfoder) foderstat vid tillsats av rödalgen, utan att ge några negativa effekter på stutarnas tillväxt. Även hos mjölkkor har metanproduktionen visat sig kunna minska med mellan 26% till 80% vid utfodring av rödalgen utan att påverka mjölkproduktionen. Rödalgens koncentration av bromoform, samt doserna av rödalg, har dock varierat mellan de olika studierna, vilket gör det svårt att göra korrekta jämförelser av rödalgens effektivitet, samt vilken dos av rödalg som är optimal att utfodra för att uppnå önskad metanreducerande effekt. På grund av det begränsade antalet djurstudier går det i dagsläget inte att dra några konkreta slutsatser kring om rödalgens förmåga att inhibera den metanbildande processen påverkas av foderstatens sammansättning. Därför krävs det fler studier som utvärderar Asparagopsis Taxiformis effekt vid olika andelar grovfoder (50% till 100%) i foderstaten, samt vid utfodring av olika grovfoderkvaliteter, t ex hög respektive låg fiberkoncentration och smältbarhet. En beräkning av kostnaden för att utfodra ett tillskott baserat på rödalgen till olika kategorier av nötkreatur visade att vid en tillskottsdos på 100 g/dag och ett pris på 150 kr/kg tillskott krävdes en merbetalning på 13,00 till 24,50 kr/kg slaktvikt för ungdjur och 0,54 kr/kg mjölk för att täcka den ökade foderkostnaden för köttrespektive mjölkproducenterna. Merkostnaden per kilo slaktvikt och mjölk berodde mer på dosen än på priset på algtillskottet. Av slaktungnöten blev det dyrast att utfodra mjölkrastjuren och billigast att utfodra mjölk×köttraskvigan med rödalgstillskottet. Kostnaden för att utfodra algtillskottet måste dock sättas i relation till den metanminskning som kan uppnås. Då ungtjurar av mjölk- och köttras bidrar med den största andelen av det svenskproducerade nötköttet är det här den största potentialen finns för att minska metanproduktionen till en rimlig kostnad. Många frågetecken kvarstår dock, t ex vad gäller rödalgens långsiktiga förmåga att minska metanproduktionen, då det längsta publicerade djurförsöket hittills enbart pågått under fem månader. Frågan är också om utfodringen med rödalger leder till rester av brom och jod i kött, inälvor och mjölk. Några av dessa frågor väntas få sitt svar i nyligen avslutade svenska försök på mjölkkor, samt i kommande Sammanfattning mjölkkoförsök som planerar att genomföras under 2021 och 2022. Det saknas även djurförsök på växande nöt och dikor under svenska förhållanden, vilket behövs för att kunna utvärdera rödalgens metanreducerande effekt vid utfodring med våra typiska grovfoderrika foderstater, samt rödalgens effekt på tillväxt hos ungdjur och dess långtidseffekter på produktion, hälsa och fertilitet hos mjölk- och dikor. Den slutliga frågan är hur en betalningsmodell för kött respektive mjölk från djur utfodrade med tillskottet skulle kunna se ut, eftersom detta tillskott enbart kommer att bli tillämpat i praktiken om producenten får betalt för sina merkostnader.
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| 8. |
- Jardstedt, Mikaela, et al.
(author)
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The Effect of Feeding Roughages of Varying Digestibility Prepartum on Energy Status and Metabolic Profiles in Beef Cows around Parturition
- 2020
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In: Animals. - : MDPI AG. - 2076-2615. ; 10
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Journal article (peer-reviewed)abstract
- Simple Summary Grass silages based on timothy-meadow fescue are commonly fed to pregnant beef cows during winter. As beef cows usually are given free access to roughage for rational reasons, the use of these silages has been questioned due to their relatively high nutritional value, which may result in nutrient intakes above animal requirements and, hence, a waste of resources. Therefore, other roughage alternatives are requested, but their effects on cow intake and energy status before calving must be evaluated before applied in practice. Four diets based on timothy-meadow fescue silage, festulolium silage plus urea, reed canarygrass silage or barley straw supplemented with urea and rapeseed meal were fed in free access to mature pregnant beef cows. Timothy-meadow fescue and festulolium diets resulted in overfeeding of energy and protein and in body weight and body condition gains, whereas the opposite was observed for cows fed the other two diets. Hence, reed canarygrass or barley straw supplemented with urea and rapeseed meal prepartum may be suitable alternatives to the traditional timothy-meadow fescue diet, if cows are able to regain lost BCS during the grazing period, and may reduce winter feed costs of the cow-calf producer due to the low intakes of these diets.Abstract Resource efficient winter-feeding of mature pregnant beef cows requires knowledge of how different roughage-based feeding strategies affect cow intake and energy status. Four diets based on traditional timothy-meadow fescue silage (TM), festulolium silage plus urea (FE), reed canarygrass silage (RC) or barley straw supplemented with urea and rapeseed meal (BR), were fed ad libitum for 16 weeks prepartum to 36 Hereford cows. Postpartum, cows were fed the same diet before release on pasture. Individual data on cow intake, changes in body weight (BW), body condition score (BCS) and plasma metabolites, calf birth and weaning weights were recorded. The TM and FE diets resulted in increased BW and BCS prepartum (p < 0.001), while the RC and BR diets resulted in a catabolic state, as indicated by a loss of BCS, lower insulin levels and higher non-esterified fatty acid levels in cows fed BR (p < 0.001). There were no dietary effects on calf parameters (p > 0.29). Feeding RC or BR prepartum might be a possible alternative to traditional timothy-meadow fescue silage if cows are allowed to regain lost BCS during the grazing period. The influence on cow reproductive- and calf performance should be considered before making this management change.
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