Designing animal production studies.

Bransby, David; Maclaurin, Angus; Mannetje, L. ‘t; Jones, R. M.

doi:10.1079/9780851993515.0327

Cited by 4 publications

(4 citation statements)

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“…, 1987; Coates and Penning, 2000). According to Bransby and Maclaurin (2000), total heifer production ha −1 can be calculated as PH × SR × T, where PH is the daily production per heifer (kg), SR is the stocking rate (heifers ha −1 ) and T is the grazing time in days.…”

Section: Grazing Experimentsmentioning

confidence: 99%

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Effects of cutting or grazing grass swards on herbage yield, nitrogen uptake and residual soil nitrate at different levels of N fertilization

Nevens

Rehuel

2003

Grass and Forage Science

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On a Flemish sandy loam soil, cut and grazed swards were compared at different levels of mineral nitrogen (N) fertilization. Economically optimal N fertilization rates were 400 (or more) and 200 kg N ha )1 yr )1 on cut and grazed swards respectively. Considering the amounts of residual soil nitrate-N in autumn, these N rates also met the current Flemish legal provisions, i.e. no more than 90 kg ha )1 nitrate-N present in the 0-90 cm soil layer, measured between 1 October and 15 November. The N use efficiency was considerably higher in cut grassland systems than in grazed systems, even when the animal component of a cut and conservation system was included. The results indicate that, for cut grasslands, two N application rates should be considered: intensively managed grasslands with high amounts of N (400 kg ha )1 yr )1 or more) or extensively managed grasslands with white clover and no more than 100 kg N ha )1 yr )1 .

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Section: Grazing Experimentsmentioning

confidence: 99%

“…Moreover, the method used incorporates grazing time as a response variable as grazing was ended on different treatments or plots at different times, based on an objective criterion – canopy height. According to Bransby and Maclaurin (2000), this time factor is often completely overlooked in experiments measuring animal production.…”

Section: Grazing Experimentsmentioning

confidence: 99%

Effects of cutting or grazing grass swards on herbage yield, nitrogen uptake and residual soil nitrate at different levels of N fertilization

Nevens

Rehuel

2003

Grass and Forage Science

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“…Lower stocking rates allow greater development of the animal, due to the higher forage accumulation, making it possible for females to have more food available [ 77 ]. Stocking rate is a primary management variable in grazing systems because it modulates the interactions between animals and pasture [ 78 , 79 ]. As stocking rate increases, herbage allowance decreases and can reach levels where intake per animal is too low for production, but intake per unit area surpasses the ability of pastures to produce and recover.…”

Section: Discussionmentioning

confidence: 99%

Direct and indirect nutritional factors that determine reproductive performance of heifer and primiparous cows

et al. 2022

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Pregnancy rate is a major determinant of population dynamics of wild ungulates and of productivity of livestock systems. Allocation of feeding resources, including stocking rates, prior to and during the breeding season is a crucial determinant of this vital rate. Thus, quantification of effects and interaction among multiple factors that affect pregnancy rate is essential for management and conservation of pasture-based systems. Pregnancy rate of 2982 heifers and primiparous cows was studied as a function of animal category, average daily gain during the breeding season, stocking rate, pasture type and body weight at the beginning of the breeding season. Data were obtained from 43 experiments conducted in commercial ranches and research stations in the Pampas region between 1976 and 2015. Stocking rate ranged from 200 to 464 kg live weight ha-1, which brackets values for most of the grazinglands in similar regions. Age at breeding was 14–36 months (24.6±7.5 months); initial breeding weights were 129–506 kg and 194–570 kg for heifers and primiparous cows. Pregnancy rate was modeled with an apriori set of explanatory variables where proximate variables (breed, body weight at start of breeding, weight gain during breeding and category) were included first and subsequently modeled as functions of other variables (pasture type, supplementation and stocking rate). This modeling approach allowed detection of direct and indirect effects (through nutrition and body weight) of factors that affect pregnancy rate. Bos taurus breeds (N = 1058) had higher pregnancy rate than B. Taurus x B. indicus crossbreed (N = 1924) females. Pregnancy rate of heifers and primiparous cows grazing in natural grasslands decreased with increasing stocking rate, but no effect of stocking rate was detected in cultivated and improved pastures. Pregnancy rate increased with increasing average daily gain during the breeding season. Use of cultivated or improved natural pastures promotes higher pregnancy rate, as well as allows an increase in stocking rate at the regional level. Body weight at the start of the breeding season is the primary determinant of pregnancy rates in heifer and primiparous cows.

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“…Lower stocking rates allow greater development of the animal, due to the higher forage accumulation, making it possible for females to have more food available (Euclides & Euclides Filho 1998). Stocking rate is a primary management variable in grazing systems because it modulates the interactions between animals and pasture (Bransby & Maclaurin 2000; Carvalho & Batello 2009). As stocking rate increases, herbage allowance decreases and can reach levels where intake per animal is too low for production, but intake per unit area surpasses the ability of pastures to produce and recover.…”

Section: Discussionmentioning

confidence: 99%

Direct and indirect nutritional factors that determine reproductive performance of heifer and primiparous cows

Eloy

Bremm

Lobato

et al. 2020

Preprint

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23Pregnancy rate is a major determinant of population dynamics of wild ungulates 24 and of productivity of livestock systems. Allocation of feeding resources, including 25 stocking rates, prior to and during the breeding season is a crucial determinant of this vital 26 rate. Thus, quantification of effects and interaction among multiple factors that affect 27 pregnancy rate is essential for management and conservation of pasture-based systems. 28 Pregnancy rate of 2982 heifers and primiparous cows was studied as a function of animal 29 category, average daily gain during the breeding season, stocking rate, pasture type and 30 body weight at the beginning of the breeding season. Data were obtained from 43 31 experiments conducted in commercial ranches and research stations in the Pampas region 32 between 1976 and 2015. Stocking rate ranged from 200 to 464 kg live weight/ha, which 33 brackets values for most of the grazinglands in similar regions. Age at breeding was 14-34 36 months (24.6 ± 7.5 months); initial breeding weights were 129-506 kg and 194-570 35 kg for heifers and primiparous cows. Pregnancy rate was modeled with an apriori set of 36 explanatory variables where proximate variables (breed, body weight at start of breeding, 37 weight gain during breeding and category) were included first and subsequently modeled 38 as functions of other variables (pasture type, supplementation and stocking rate). This 39 modeling approach allowed detection of direct and indirect effects (through nutrition and 40 body weight) of factors that affect pregnancy rate. Taurine (Bos taurus breeds, N = 1058) 41 had higher pregnancy rate than B. Taurus x B. indicus crossbreed (N = 1924) females.42Pregnancy rate of heifers and primiparous cows grazing in natural grasslands decreased 43 with increasing stocking rate, but no effect of stocking rate was detected in cultivated and 44 improved pastures. Pregnancy rate increased with increasing average daily gain during 45 the breeding season. Use of cultivated or improved natural pastures promotes higher 3 46 pregnancy rate, as well as allows higher in stocking rate at the regional level. Body weight 47 at the start of the breeding season is the primary determinant of pregnancy rates in heifer 48 and primiparous cows. 49 50 4 70changes in economic and technological factors that affect productivity (IBGE 2020). Low 71 pregnancy rates prevent full development of the livestock sector in many regions of the 72 world, and it may be associated with poor pasture management, overstocking and lack of 73 differential nutritional management for animal categories with different requirements. 74Stocking rate is considered the most important decision in grazing management because 75 it affects the forage base, herbage allowance, intake and animal performance 76 (Sollenberger, Agouridis, Vanzant, Franzluebbers & Owens 2012). Nutritional limitation 77 during periods of high requirement can compromise development and delay puberty of 78 heifers, as well as inhibit ovulation of cows (Rocha & Lobat...

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Designing animal production studies.

Cited by 4 publications

References 0 publications

Effects of cutting or grazing grass swards on herbage yield, nitrogen uptake and residual soil nitrate at different levels of N fertilization

Effects of cutting or grazing grass swards on herbage yield, nitrogen uptake and residual soil nitrate at different levels of N fertilization

Direct and indirect nutritional factors that determine reproductive performance of heifer and primiparous cows

Direct and indirect nutritional factors that determine reproductive performance of heifer and primiparous cows

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