Production and metabolic effects of site of starch digestion in dairy cattle

Reynolds, C.K.

doi:10.1016/j.anifeedsci.2006.01.019

Cited by 132 publications

(142 citation statements)

References 52 publications

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“…On a net basis, AA removed by the liver are a major source of carbon for glucose synthesis, and there has been much speculation that increasing glucose or propionate absorption may increase milk protein secretion through a reduction in AA use for glucose synthesis that spares AA use for milk protein synthesis. However, to our knowledge, there is no evidence of an effect of increased glucose or propionate absorption on liver removal of AA (Reynolds, 2006b;Larsen and Kristensen, 2009), or an effect of increased AA supply on liver glucose synthesis (Reynolds, 2006b). However, the primary gluconeogenic AA in the liver are non-EAA, and therefore any sparing of these AA from glucose synthesis would be unlikely to increase the supply of EAA to the mammary gland.…”

Section: Factors Affecting the Efficiency Of N Utilization In The Pdvmentioning

confidence: 82%

“…The observation that gut enterocytes use glucose, the acidic AA (Glu, Asp) and Gln as energy substrates has fuelled speculation that providing more glucose for absorption in the small intestine would spare AA, increasing their absorption into blood, and thus their availability for milk protein synthesis. However, there is no evidence of which we are aware that increased intestinal starch or glucose supply increases net PDV appearance of AA in lactating dairy cows (Reynolds, 2006b;Larsen and Kristensen, 2009), and it is unlikely that any effects would extend beyond the utilization of non-EAA.…”

Section: Factors Affecting the Efficiency Of N Utilization In The Pdvmentioning

confidence: 95%

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Strategies for optimizing nitrogen use by ruminants

Calsamiglia

Ferret

Reynolds

et al. 2010

Animal

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The efficiency of N utilization in ruminants is typically low (around 25%) and highly variable (10% to 40%) compared with the higher efficiency of other production animals. The low efficiency has implications for the production performance and environment. Many efforts have been devoted to improving the efficiency of N utilization in ruminants, and while major improvements in our understanding of N requirements and metabolism have been achieved, the overall efficiency remains low. In general, maximal efficiency of N utilization will only occur at the expense of some losses in production performance. However, optimal production and N utilization may be achieved through the understanding of the key mechanisms involved in the control of N metabolism. Key factors in the rumen include the efficiency of N capture in the rumen (grams of bacterial N per grams of rumen available N) and the modification of protein degradation. Traditionally, protein degradation has been modulated by modifying the feed (physical and chemical treatments). Modifying the rumen microflora involved in peptide degradation and amino acid deamination offers an alternative approach that needs to be addressed. Current evidence indicates that in typical feeding conditions there is limited net recycling of N into the rumen (blood urea-N uptake minus ammonia-N absorption), but understanding the factors controlling urea transport across the rumen wall may reverse the balance to take advantage of the recycling capabilities of ruminants. Finally, there is considerable metabolism of amino acids (AA) in the portal-drained viscera (PDV) and liver. However, most of this process occurs through the uptake of AA from the arterial blood and not during the 'absorptive' process. Therefore, AA are available to the peripheral circulation and to the mammary gland before being used by PDV and the liver. In these conditions, the mammary gland plays a key role in determining the efficiency of N utilization because the PDV and liver will use AA in excess of those required by the mammary gland. Protein synthesis in the mammary gland appears to be tightly regulated by local and systemic signals. The understanding of factors regulating AA supply and absorption in the mammary gland, and the synthesis of milk protein should allow the formulation of diets that increase total AA uptake by the mammary gland and thus reduce AA utilization by PDV and the liver. A better understanding of these key processes should allow the development of strategies to improve the efficiency of N utilization in ruminants. Keywords: ruminant, nitrogen efficiency ImplicationsRuminants have a low efficiency of N utilization compared with non-ruminants. This low efficiency has implications not only for production performance and economic efficiency but also for the emission of contaminants to the environment. The efficiency of N utilization can be improved through the understanding and modification of factors regulating the efficiency of N utilization in key processes, including N capture in the rumen, ...

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Section: Factors Affecting the Efficiency Of N Utilization In The Pdvmentioning

confidence: 82%

Section: Factors Affecting the Efficiency Of N Utilization In The Pdvmentioning

confidence: 95%

Strategies for optimizing nitrogen use by ruminants

Calsamiglia

Ferret

Reynolds

et al. 2010

Animal

Self Cite

260

165

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“…Moreover, the degradation of maize starch may be so slow that it does not completely undergo fermentation in the rumen (McCarthy et al, 1989) and is instead digested post-ruminally or excreted in faeces. If digested in the small intestine, it would increase its efficiency as a source of energy for milk production (Reynolds, 2006). Previous studies have reported that feeding maize-based concentrates resulted in greater dry matter intake (DMI) than barley-based concentrates for alfalfa-and maize silage-based diets (McCarthy et al, 1989;Overton et al, 1995).…”

Section: Introductionmentioning

confidence: 99%

“…Previous studies have reported that feeding maize-based concentrates resulted in greater dry matter intake (DMI) than barley-based concentrates for alfalfa-and maize silage-based diets (McCarthy et al, 1989;Overton et al, 1995). The importance of the interactions between qualities of fibre and starch in studies of intake regulation has been highlighted in a review of Reynolds (2006), suggesting that the positive interactions may result in improved DMI and animal performance in terms of milk production (Dixon and Stockdale, 1999). Despite the expected beneficial effects on intake and performance, few studies have been reported in which the interaction effects between concentrate starch source and forage digestibility have been examined when fast-degrading starch from barley was replaced with slow-degrading starch from maize in high or medium digestibility grass silage-based diets.…”

Section: Introductionmentioning

confidence: 99%

“…A strategy to reduce the potential negative effects of high concentrations of starch in the rumen is to utilize total mixed rations (TMR) instead of feeding the concentrates separately (Reynolds, 2006). Hetta et al (2010) found relatively low substitution effect on forage intake when the proportions of wheat grain inclusion were raised in maize-and grass silagebased diets, and suggested that the TMR feeding regime might be beneficial for promoting high forage intake in diets with high concentrations of starch.…”

Section: Introductionmentioning

confidence: 99%

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The effects of and interactions between the maturity of grass silage and concentrate starch source when offered as total mixed rations on the performance of dairy cows

Tahir

Lund

Hetta

2013

Animal

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A 2 3 2 factorial feeding experiment was conducted to examine the effects of varying the maturity level of the grass used to prepare silage and the nature of concentrate starch source and their interactions on dry matter intake (DMI), diet digestibility, energy corrected milk (ECM) production and milk composition in dairy cows. Twenty-eight multiparous Swedish Red dairy cows, 133 6 45 days in milk (DIM), with an average milk yield of 30 6 4 kg/day and a live weight of 624 6 69 kg were blocked by DIM and randomly assigned to seven replicated balanced 4 3 4 Latin squares with four 21-day experimental periods. The experimental diets consisted of four total mixed rations (TMR) consisting of early-cut grass silage (EGS) supplemented with either barley-or maize-based concentrate and late-cut grass silage (LGS) supplemented with either barley-or maize-based concentrate. All TMR contained identical proportions of forage (51%) and concentrate (49%). Total tract digestibility was estimated by determining indigestible NDF (iNDF) concentrations in feeds and faeces and using iNDF as an internal marker. The feeds' ruminal degradation parameters were determined using both in situ (nylon bag) and in vitro (gas production (GP)) techniques. Cows offered diets containing EGS had greater (P , 0.001) daily dry matter (DM) intakes, ECM yields and total tract digestibilities for DM and organic matter (OM), but these were not affected by the nature of the concentrate starch source. No interaction between the maturity of the silage and the nature of the concentrate starch source was observed for DMI, diet digestibility or ECM yield. Both grass silages and concentrates had similar rates of ruminal degradation of NDF when measured in situ. The in situ DM (P , 0.001) and starch (P 5 0.001) degradation rates of barley-based concentrate were greater than those for maize-based concentrate. In vitro OM GP rates and extents were similar for both concentrate feeds. The results showed that diets containing EGS offered better animal performance and diet digestibility than diets containing LGS. The concentrate starch source did not affect animal performance, but total NDF digestibility was better with diet containing barley-than maize-based concentrate.

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Effect of feeding slowly fermentable grains on productive variables and amelioration of heat stress in lactating dairy cows in a sub-tropical summer

Gonzalez-Rivas

Sullivan

Cottrell

et al. 2018

Trop Anim Health Prod

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Feeding low-fiber and high-energy diets to dairy cows is one approach to ameliorate heat stress (HS) by reducing heat increment (HI) during digestion. However, rapidly and slowly fermentable cereal grains differ in their HI. The aim of this experiment was to quantify if feeding slowly fermentable grains ameliorated the physiological responses to HS and improved milk production (MP) in dairy cows. Holstein-Friesian lactating dairy cows were housed in shaded pens and were fed either a total mixed ration (TMR) plus wheat (TMRW), a TMR plus wheat treated with 2% of a commercial starch-binding agent (TMRB), or a TMR plus corn (TMRC) (n = 8 cows per diet) during summer in Queensland, Australia. Respiration rate (RR) and panting score (PS) were measured four times a day; rumen temperature (RuT) was recorded every 20 min, and rectal temperature (RT) and milk samples were obtained every 4 days. Cows fed slowly fermentable grains had higher milk production (MP) than cows fed TMRW, and cows fed TMRC had lower RT than those fed TMRW and TMRB (P < 0.001). Rumen temperature was positively correlated with temperature-humidity index and negatively correlated with MP (P < 0.05). In summary, feeding TMRC ameliorated HS as indicated by lower RT and improved MP in dairy cows. Milk production was improved with starch-binding agents; however, this was not associated with efficient thermoregulatory responses. Furthermore, determination of RuT enabled the prediction of changes in physiological variables and productive responses due to HS in lactating dairy cows.

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Production and metabolic effects of site of starch digestion in dairy cattle

Cited by 132 publications

References 52 publications

Strategies for optimizing nitrogen use by ruminants

Strategies for optimizing nitrogen use by ruminants

The effects of and interactions between the maturity of grass silage and concentrate starch source when offered as total mixed rations on the performance of dairy cows

Effect of feeding slowly fermentable grains on productive variables and amelioration of heat stress in lactating dairy cows in a sub-tropical summer

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