Modeling of off-feed periods caused by subacute acidosis in intensive lactating ruminants: Application to goats

Abstract

Off-feed periods caused by subacute rumen acidosis are often observed in intensive ruminant production systems but appear in an unpredictable manner. The objectives of this paper were first, to study the influence of spontaneous off-feed periods due to bouts of acidosis on milk composition and on some rumen and blood parameters and second, to model the day-to-day variations in rumen pH, dry matter intake (DMI), and milk production during these bouts of acidosis. Twenty-five spontaneous off-feed periods were detected in an experiment performed in 18 mid-lactating goats fed a high concentrate diet over 11 wk. Dry matter intake, milk production, and rumen pH were measured daily during the experiment, which allowed us to model the day-to-day evolution of these 3 parameters during spontaneous bouts of acidosis. Bouts started with a very rapid pH decrease (1 d) followed by several days of relatively high rumen pH (>6.5) before recovery of preacidosis values. The pH decrease was followed by a decrease in DMI, reaching a nadir around 2 d after the start of the episode, and a milk yield decrease, reaching a nadir 3 d after the beginning of the episode. The high rumen pH was caused by the relatively small decrease in daily chewing time during the decrease in DMI. Therefore, chewing time per unit of DMI increased, which probably increased the buffer supply per unit of DMI. Dry matter intake and milk yield needed around 20 d to recover to preacidosis values. Energy balance also decreased during DMI and milk yield decreases but recovered more rapidly than DMI and milk yield. However, energy balance cumulated from the start of the bout of acidosis remained negative for more than 10 d. Milk composition and rumen and blood parameters were not measured daily and therefore could not be used in the modeling process. However, during off-feed periods, milk fat and protein contents were negatively correlated with DMI, whereas milk lactose content was positively correlated with DMI. Low DMI was also linked to low blood pH, bicarbonates, and low rumen volatile fatty acids but high levels of plasma nonesterified fatty acids. This indicates that rumen fermentation was reduced and body reserves were mobilized during bouts of acidosis. This analysis showed that spontaneous bouts of acidosis in intensively reared dairy ruminants can have a great influence on animal production and health over at least 3 wk, and can thus represent an important economic loss.

Effect of concentrate level on feeding behavior and rumen and blood parameters in dairy goats: Relationships between behavioral and physiological parameters and effect of between-animal variability

“…However, when receiving the LO diet, fill load limited goat feed consumption (physical regulation; Montgomery and Baumgardt, 1965). Moreover, half of the goats when fed the HI diet showed some off-feed periods, as evidenced by the very low values for intake and by the high standard deviation of the DMI, which can be considered as a sign of SARA (Fulton et al, 1979;Nocek, 1997;Desnoyers et al, 2009b). These results were not dependent on mineral and vitamin contents, as both diets had similar final levels brought by the mineral/vitamin premix.…”

“…Dry matter intake was expressed on a BW basis using the BW measured during the previous week. As off-feed periods and irregularities in DMI are considered to be a sign of SARA, decreases in DMI between 2 consecutive days greater than 10 g/kg of BW were counted (Desnoyers et al, 2009b) during the last 21 d of each period (d 8 to 28).…”

“…The effect of increasing the percentage of concentrate on milk production or on digestion has been studied for a long time (Bloom et al, 1957;Kesler and Spahr, 1964). The consequence of this increase on the occurrence of SARA is also well known in dairy cows as stated in some reviews (Nocek, 1997;Owens et al, 1998;Sauvant and Peyraud, 2010) but has seldom been studied in dairy goats (Hadjipanayiotou, 2004;Desnoyers et al, 2009b). However, there is a lack of papers dealing with the relationship between feeding behavior and rumen function (González et al, 2012) and with the consequent outcomes on blood composition and milk production measured in the same animals.…”

Approche quantitative de l’aidose chez les ruminants

“…Aussi la valeur moyenne du pH est-elle la donnée la plus fréquemment utilisée. (Desnoyers et al 2009b). Il apparait qu'après une chute brutale et imprévisible du pH au jour J0, celui-ci revient à la normale dès J1, pour être à un niveau plus élevé les jours suivants.…”

Vers des définitions opérationnelles de la robustesse s’appuyant sur des faits biologiques. L’exemple de la nutrition.

“…Les animaux présentant des réactions fortes au cours de ces épisodes pourraient ainsi être distingués de ceux présentant une relative résistance. Un exemple de ce type de variabilité entre individus a été publié récemment à propos des épisodes d'acidoses chez la chèvre laitière (Desnoyers et al 2009). La réponse propre de chaque animal, et ainsi sa robustesse, pourrait être quantifiée, mais cette identification requiert en premier lieu une haute fréquence de mesures.…”