Motivation to obtain a food reward of pregnant ewes in negative energy balance: behavioural, metabolic and endocrine considerations

Low food availability often coincides with pregnancy in grazing animals. This study investigated how chronic reductions in food intake affected feeding motivation, and metabolic and endocrine parameters in pregnant sheep, which might be indicative of compromised welfare. Ewes with an initial Body Condition Score of 2.7±0.3 (BCS; 0 indicates emaciation and 5 obesity) were fed to attain low (LBC 2.0±0.0,), medium (MBC 2.9±0.1) or high BCS (HBC 3.7±0.1) in the first trimester of pregnancy. A feeding motivation test in which sheep were required to walk a set distance for a palatable food reward was conducted in the second trimester. LBC and MBC ewes consumed more rewards (P=0.001) and displayed a higher expenditure (P=0.02) than HBC ewes, LBC ewes also tended to consume more rewards than MBC ewes (P=0.09). Plasma leptin and glucose concentrations were inversely correlated to expenditure (both P<0.05) and appear to be associated with hunger in sheep. LBC ewes were in negative energy balance, with lower muscle dimensions, plasma glucose, leptin, insulin, cortisol, and insulin-like growth factor-1 concentrations and higher free fatty acids concentrations compared to HBC ewes; metabolic and endocrine parameters of the MBC ewes were intermediate. The high feeding motivation and negative energy balance of low BCS ewes suggested an increased risk of compromised welfare. Imposing even a small cost on a food reward reduced motivation substantially in high BCS ewes (despite high intake when food was freely available). Assessment of a willingness to work for rewards, combined with measures of key metabolic and endocrine parameters, may provide sensitive barometers of welfare in energetically-taxed animals.

Performance of growing lambs fed processed karanj (Pongamia glabra) oil seed cake as partial protein supplement to soybean meal

The aim of this study was to determine whether processed karanj (Pongamia glabra) oil seed cake can be used as a supplement to partially replace soybean meal (SBM). Male lambs (n = 24) of uniform body weight (12.88 +/- 0.15 kg) were equally allotted at random to a SBM-based control (CON) and three test concentrate mixtures, containing detoxified solvent extracted karanj cake (SKC) using three processing methods: water washing (WW), 2.5% lime (LM) and 0.4% binder (BN) treatment. The processed SKC replaced 50% nitrogen of SBM of CON. The respective concentrate mixtures were fed along with ad libitum chaffed oat (Avena sativa) straw for 196 days. Dry matter intake was significantly (p < 0.01) lower on WW, LM and BN. Apparent digestibility coefficient of nutrients was comparable, except for total carbohydrates, which was significantly (p < 0.01) lower in LM and BN. Total gain, average daily gain and feed: gain ratio was comparable (p > 0.05) between the CON and WW diets but significantly lower in LM and BN groups. Yield of greasy wool was lower (p < 0.05) in BN group. Comparable dry matter and nutrient (crude protein and total digestible nutrients) conversion efficiency was observed on CON and WW diet but the lambs on the LM and BN diets exhibited lower (p < 0.01) conversion efficiency. It is concluded that SKC after water washing could replace 50% of SBM nitrogen in protein supplementation.