A moderate protein diet does not cover the requirements of growing rabbits with high growth rate

Marín-García, Pablo Jesús; Ródenas, L.; Martínez-Paredes, E.; Cambra‐López, María; Blas, E.; Pascual, Juan José Montero

doi:10.1016/j.anifeedsci.2020.114495

Cited by 21 publications

(25 citation statements)

References 23 publications

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“…The CTTAD and AID values obtained in this study agree with those of other trials carried out with this same paternal genetic line and using similar diets [ 13 ]. Additional supplementation of the first three limiting amino acids did not affect the CTTAD of the main nutrients.…”

Section: Discussionsupporting

confidence: 89%

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Do Growing Rabbits with a High Growth Rate Require Diets with High Levels of Essential Amino Acids? A Choice-Feeding Trial

Marín-Garcia

López-Luján

Ródenas

et al. 2021

Animals

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As a consequence of the genetic selection process in growing rabbits, there are currently fast-growing animals exhibiting an average daily gain that may exceed 45 g/d. The protein requirements of these animals, namely amino acid requirements, may differ from animals with low growth rates. The objective of this work was to evaluate growth performance, the coefficient of total tract apparent digestibility (CTTAD), the apparent ileal digestibility (AID) of amino acids and nutrient retention of fast-growing rabbits when they had access to a diet with high levels of amino acids and/or a diet formulated with current nutritional recommendations in a choice-feeding trial. To this end, two diets were formulated: the M diet following current nutritional recommendations for growing rabbits (including 8.1, 5.8 and 6.9 g/kg dry matter (DM) of total lysine, sulphur amino acids and threonine, respectively) and the H diet with higher levels of total lysine, sulphur amino acids and threonine (9.4, 6.6 and 7.8 g/kg DM, respectively). A total of 220 weaned rabbits, from a paternal line selected for the growth rate, had free access to the M diet, the H diet or both (MH) diets from 28 to 63 days of age. The CTTAD of DM, crude protein and gross energy from 49 to 53 days of age as well as the AID of amino acids of the diets at 63 days of age were determined. Protein, amino acids and energy retained in the empty body from 28 to 63 days of age were also registered. No significant differences in growth performance, CTTAD, AID and nutrient retention between dietary treatments were observed. However, animals fed the H diet showed a higher AID of cysteine (p < 0.05) and higher threonine retention (p < 0.05) compared to the M diet. As regards the choice-feeding trial, MH animals showed a higher feed intake of the M diet compared to the H diet (+8.61%; p < 0.001), and furthermore, more than 50% of the animals preferred the M diet throughout the experimental period (p < 0.05). Our results suggest that animals with high growth rates do not show significantly higher productive traits when fed the H diet compared to the M diet. As regards choice feeding, MH animals were capable of choosing their preferred diet, showing high intra-individual repeatability in preference for the M diet. It would be interesting to continue studying this behaviour of choice based on amino acid levels.

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Section: Discussionsupporting

confidence: 89%

“…In previous research, ref. [ 12 , 13 ] outlined the existence of some limiting amino acids when current moderate-protein diets are used in fast-growing rabbits.…”

Section: Introductionmentioning

confidence: 99%

Do Growing Rabbits with a High Growth Rate Require Diets with High Levels of Essential Amino Acids? A Choice-Feeding Trial

Marín-Garcia

López-Luján

Ródenas

et al. 2021

Animals

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“…This basal mixture was formulated following the recommendations of all nutrients for growing rabbits [ 6 ], with a moderate content of CP (155 g/kg DM) and DE (9.86 MJ/kg DM). The contents of lysine, sulphur amino acids and threonine were variable (in a previous work, [ 4 ]) from the linear regression between protein retention and growth rate, we observed that protein retention in rabbit having very high growth rate was lower than expected, what would indicate some deficiency in amino acid supply. Then, we decided to compare PUN (a marker of the efficiency in the amino acid use) in rabbits with high growth rate fed with diets close to the current recommendations of the 3 main amino acids (medium), or having levels 15% higher (high) or 15% lower (low) of each.…”

Section: Methodsmentioning

confidence: 54%

“…Thus, with a diet containing 179 g CP/kg DM, [ 2 ] did not observed differences in relative growth, while when a diet with 161 g CP/kg DM was used, animals selected by growth rate had greater dissectible fat percentage and lower meat to bone ratio [ 3 ]. The authors of [ 4 ] showed that animals selected by growth rate had lower protein retention and higher energy retention than expected. On the other hand, as a consequence of the irruption of the epizootic rabbit enteropathy, dietary protein content has tended to be reduced nowadays [ 5 ].…”

Section: Introductionmentioning

confidence: 99%

Plasmatic Urea Nitrogen in Growing Rabbits with Different Combinations of Dietary Levels of Lysine, Sulphur Amino Acids and Threonine

Marín-Garcia

López-Luján

Ródenas

et al. 2020

Animals

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A total of 27 experimental diets were formulated starting from the same basal mixture, with a moderate content of crude protein and digestible energy (155 g and 9.86 MJ/kg of digestible matter (DM), respectively, both estimated). The contents of lysine, sulphur amino acids and threonine were variable. The first one, close to the current recommendations (Medium, M; 8.1, 5.8 and 6.9 g/kg DM for lysine, sulphur amino acids and threonine, respectively), and two other levels were on average 15% higher (High, H; 9.4, 6.6 and 7.8 g/kg DM for lysine, sulphur amino acids and threonine, respectively) or lower (Low, L; 6.7, 4.9 and 5.7 g/kg DM for lysine, sulphur amino acids and threonine, respectively). Diets were named with three letters, indicating lysine, sulphur amino acids and threonine levels, respectively. In total, 918 weaned rabbits (28 days old) were used (34 per diet). At weaning, animals were fed ad libitum with a commercial diet until day 46, day 47 each collective cage was randomly switched to one experimental diet. At day 48, blood samples were collected at 08:00h then the animals were subjected to 10 h of fasting and a second blood sample was extracted at 21.00h. At 08:00h, Pasmatic urea nitrogen (PUN) was higher with the L level of lysine (p < 0.001), unaffected by the level of sulphur amino acids and increased with the level of threonine (p < 0.001). At 21:00h, minimum PUN was observed with the MHL diet (14.72 ± 0.661 mg/dL). Taken into account the usual recommendations (established for a diet containing 11.3 MJ DE/kg DM, and then being 0.72, 0.51 and 0.61 g/MJ DE for lysine, sulphur amino acids and threonine, respectively), these results suggest that a diet containing more lysine and sulphur amino acids per energy unit (around 0.82 and 0.67 g/MJ DE) could better fit the growing rabbit requirements, although studies on the effects of such a diet on performance and protein retention are necessary.

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“…As a consequence of this dietary protein limitation, selection by ADG could have been penalised (Marín-García et al, 2019), affecting the phenotypic expression of high ADG animals and consequently the definition of the rankings. In fact, although FCR has improved considerably, differences in FCR between maternal and paternal lines described several years ago are quite similar to those currently observed (Marín-García et al, 2019;Feki et al, 1996). This possible protein deficit was suggested in a previous study, where animals with high ADG (>55 g/d) fed according to current protein recommendations had lower body protein retention than expected as a function of their ADG (Marín-García et al, 2016).…”

Section: W O R L D R a B B I T S C I E N C Ementioning

confidence: 99%

Plasma urea nitrogen as an indicator of amino acid imbalance in rabbit diets

et al. 2020

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In recent decades, recommendations on dietary protein content have been considerably reduced, while fibre content has been increased. Under these conditions, an adequate dietary amino acid balance could be crucial to optimise feed efficiency. Plasma urea nitrogen (PUN) level could be a good indicator of an amino acid imbalance and its potential has already been studied in other species, but not yet in rabbits. The main objective of the present work was to detect the possible interest of PUN in pinpointing amino acid deficiencies in rabbits. Two experimental diets were formulated from the same basal mixture, following all the recommendations for growing rabbits, except lysine, whose content was variable, following current guidelines in diet P8.1 or lower from those in P4.4 (with 8.1 and 4.4 g/kg dry matter of lysine and with 757 and 411 mg of lysine per MJ of digestible energy). Three different trials were designed: one where the animals were fed ad libitum (AL) and two others in which fasting periods of 10 h were included; one where feeding was restored at 08:00 h (Fast8h) and the other at 18:00 h (Fast18h). A total of 72 three-way crossbred growing rabbits (24 animals for each trial in a split-plot trial) up to a total of 12 recordings were used. Blood samples were taken every 4 h in AL trial and every hour after refeeding up to a total of six controls, in trials Fast8h and Fast18h. The differences between balanced and unbalanced diets in lysine were highest (P<0.001) between 04:00 h and 12:00 h in animals fed ad libitum, and at 3 h after refeeding (21:00 h) in Fast18h. These results suggest that PUN could be an adequate indicator to detect deficiencies in amino acids in growing rabbit diets.

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A moderate protein diet does not cover the requirements of growing rabbits with high growth rate

Cited by 21 publications

References 23 publications

Do Growing Rabbits with a High Growth Rate Require Diets with High Levels of Essential Amino Acids? A Choice-Feeding Trial

Do Growing Rabbits with a High Growth Rate Require Diets with High Levels of Essential Amino Acids? A Choice-Feeding Trial

Plasmatic Urea Nitrogen in Growing Rabbits with Different Combinations of Dietary Levels of Lysine, Sulphur Amino Acids and Threonine

Plasma urea nitrogen as an indicator of amino acid imbalance in rabbit diets

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